Gold Dredging in California
Page. No. 37. Indiana Gold Dredging and Mining Company's dredges, No. 1 and No. 2, The items of costs of operation
Overview
Gold Dredging in California is a 1905 historical mining reference by J. E. Doolittle, preserved in the Mountain Man Mining research library.
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BULLETm Ko. 3« SIR FRAHOSCa lUY, IWS
Gold Dredging
In California
The California State Mining Bureau
Ferry Building, San Francisco
LEWIS E. AUBURY - - State Mineralogist
Sacramento
W. W. Shannon . - - - Superintendent State Printing
"b
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Letter Of Transmittal.
To Hon. George C. Pardee, Governor of California, and the Honorable Board of Trustees of the State Mining Bureau:
Gentlemen: I have the honor to transmit Bulletin No. 36, **Gold Dredging in California.'' The issuance of this Bulletin has been contemplated for some time, and some information concerning the subject was obtained in 1902, but owing to the rapid changes which have affected this branch of the gold mining industry, and the diflSculty met with in securing accurate data which would serve to illustrate the actual conditions of gold dredging in this State, it has been deemed best to delay the publication of the report until the present time.
The items of costs of operation, which are so vital to a publication of this nature, have been extremely diflGlcult to obtain from many of the companies engaged in dredging. This has not been due particularly to any intention on the part of the companies to withhold the information, but to the fact that many operators have not until recently preserved a detailed record of expenditures.
I wish to here extend many thanks to Col. J. E. Doolittle for his valuable assistance in the preparation of this Bulletin, and also to the many operators who have furnished information and assistance which have made this publication possible.
I also wish to thank Mr. O. W. Jasper of Oroville, Mr. Howard D. Smith, and Mr. A. H. Ward, who rendered assistance; also many others whose names are not here mentioned and who have aided in the work by furnishing valuable information.
Engaged at various times in securing data for this report, and who were employed as Field Assistants, were Mr. P. C. Dubois, Mr. John D. McGillivray, Mr. William Forstner, and Mr. G. Holmes, to whom I wish to express due recognition for their services.
Very truly,
LEWIS E. AUBURY, State Mineralogist.
San Francisco, May 15, 1905.
Contents.
History 7
Area Op Dredge Gravel 14
Geology 16
Agriculture 17
Yield For 1903 19
The Dredge 19
Screens, Sluices, Etc. 35
Crew Of A Dredge 41
Working Costs 42
Prospecting And Examination Of Conditions 60
Oroville District 68
Yuba District 88
Bear River District 91
Folsom District 92
Calaveras County 98
Plumas County 98
Shasta County - - 98
Trinity County 102
Siskiyou County 106
APPENDIX-CALIFORNIA STATE MINING BUREAU Ill
DREDGE DATA Folder
List Of Illustrations.
Page.
No. L Relief map of California _ Frontispiece
2. Map of Oroville dredging lands Folder
3. An *'old timer" _ 8
4. The old method of working the ground below Oroville 9
5. Treat's old workings on Feather River 11
6. First successful dredge in California -. 12
7. Marion steam shovel dredge, Oroville _ 13
8. Tailings piles after dredging _ 18
9. Dredger hull, in course of construction _ _ 20
10. Dredger in course of construction, showing steel gauntry _ 1.. 21
11. Digger end of ladder — latest type of close-connected buckets. Bucyrus type 22
12. Digger end of ladder— latest type of intermittent buckets. Risdon type... 23
13. Digger starting cut on top of ground 24
14. Bucket line in operation _.. . 24
16. Close-connected buckets, 5 cubic feet capacity _ _ 28
1 7. Open-connected buckets, 6 cubic feet capacity, Risdon type 29
18. Boston and Oroville Company's dredge, showing spuds. ___«. 31
19. Tailings stacker, belt conveyor 32
20. Tailings stacker, bucket conveyor 33
21. Latest bucket stacking ladder _. 34
22. Showing sand pump working 34
23. Showing revolving screen 36
24. Gold-saving tables — Hungarian riffles and quicksilver 37
25. Gold-saving tables— cocoa matting and expanded metal riffles _ 39
26. Bucyrus type of dredge, with close-connected buckets, shaking screens, belt
conveyor, and spuds _-. 43
27. Risdon type of dredge, with open-connected buckets, revolving screen,
bucket conveyor, and headlines 45
28. Oroville Gold Dredging and Exploration Company's dredge, ** Biggs No. 2 " 53
29. Keystone drill at work at Oroville to prospect for values and determine
character of gravel 62
30. Typical vertical sections of borings in four different California fields 64
31. General view of the Oroville dredging district _ 68
32. General view of the Oroville dredging ground on Feather River, looking
north 69
33. Dredge of the Feather River Exploration Company, Oroville. Risdon type 71
34. Front end of Dipper dredge, Oroville _ _._ 72
35. Stacker end of dredge, showing height of tailings piles. Lava Beds
Dredging Co., Oroville 72
36. Oroville Gold Dredging Company's dredge, Marion steam shovel type. . . 74
b LIST OF ILLUSTRATIONS.
Page. No. 37. Indiana Gold Dredging and Mining Company's dredges, No. 1 and No. 2,
Bucyrus type 76
38. Indiana Gold Dredging and Mining Company's dredge, Bucyrus type,
showing close-connected buckets ___ 76
39. Kia Ora dredge, Oroville. Risdon type 77
40. Cherokee dredge, Oroville. Bucyrus type _ 79
41. Pennsylvania Gold Dredging Company 80
42. Pennsylvania Gold Dredging Company's dredge, Oroville. Golden State
and Miners' Iron Works, builders _ 81
43. El Oro Dredging Company's dredge, Oroville. Link Dredge Machine Com-pany
's type - - 82
44. Viloro dredge, Oroville. Latest type Bucyrus dredge _ 83
45. Boston and Oroville Dredging Company's dredge, Oroville. Risdon type. _ 84
46. Boston and Oroville Dredging Company's dredge, "Continental." Bucyrus
type as remodeled _ 85
47. California No. 3, Oroville, built by the Marion Steam Shovel Company 86
48. Marigold No. 1 , Marigold Dredging Company, near Oroville 87
49. Front view of the Marigold Dredging Company's dredge, near Oroville ..- 87
50. Stacker end of Marigold Dredging Company's dredge 89
61. Yuba Consolidated Gold Fields dredges, each of 6 cubic feet bucket capacity.
Bucyrus type 89
52. Yuba Consolidated Gold Fields dredges, each of 6 cubic feet bucket capacity.
Bucyrus type __- 90
63. Ashburton Mining Company's dredge, at Folsom, Sacramento County.
Buckets 7i cubic feet capacity - 94
54. El Dorado No. 1, Folsom field. Latest type of Risdon boat 95
65. Dredge of the Colorado-Pacific Gold Dredging Company, Folsom 96
56. Syndicate Mining Company's dredge, Folsom. Bucyrus type 97
57. The bedrock of the Sacramento River at the mouth of Middle Creek, above
Redding — - 99
58. Current breakers and caissons of the Huron Submarine Mining and Construction
Company, at Redding _-_ 101
50. Huron Submarine Mining and Construction Company's caisson dredge,
above Redding _ 101
60. Galvin Gold Dredging Company of Weaverville, Trinity County 102
61. Galvin Gold Dredging Company's dredge, Trinity County, showing character
of gravel - - 103
62. Poker Bar dredge, Trinity County _. -- 104
63. Dredge of the Yreka Creek Gold Dredging and Mining Company, Siskiyou
County -- - 106
64. Consolidated Mining and Dredging Company's dredge and caisson 107
65. Ferry Building, San Francisco --- 110
66. Mineral Museum, State Mining Bureau 113
67. Library and Free Reading-Room, State Mining Bureau -_ 115
68. Laboratory, State Mining Bureau 117
69. Map of field of operations in Folsom District, showing locations of dredging
companies ..-- - Folder
"0. "Dredge Data" -- - ...Folder
r
Gold Dredging In California.
History.
It is populaxly supposed that mining for gold with dredges is an industry which has grown up within the last decade, and that it was a success almost from the beginning. This is not true. There are bleaching skeletons of dredges scattered over California and New Zealand, some of which were built nearly half a century ago. There -was a dredge near Oroville, on the Feather River, in the fifties. It is over forty years since dredging was first tried in New Zealand. Spasmodic attempts were made in this direction on the Pacific Coast and in New Zealand from that time on. These efforts, futile as they were, so far as giving dividends to shareholders go, were of great value to the miner and mining engineer of to-day. These failures were their warnings.
As a result, this class of mining, if properly directed, is now as safe as any, provided that skilled investigators direct the investment and use of capital, and see that it is only invested where conditions permit of successful work.
Any one investigating the processes at Oroville or Folsom, or in New Zealand, where conditions are known by actual practice, will find that the diflSculties have been la'rgely overcome because the conditions have been studied by skilled men at large expense, and met with appliances fitted for the local needs, not only as to the digging of the ground, but also as to the saving cf the gold.
But under other conditions, in other districts, the dredges so successful at Oroville or Fokom, or in New Zealand, would be failures as to some of their parts. To explain: At Oroville, the gravel is loose, free from clay. There are no large bowlders, the bedrock is soft, the gold is fine and it easiiy amalgamates. Along the streams in the mountains of California the bowlders are larger, the bedrock harder, and in places in Idaho end Colorado the gold will not amalgamate owing to the presence of arsenic. Then there are many other conditions that differ in other places. Some of these diflSculties may be overcome by slight changes, either in the digging part of the dredge
8 OOIiD DREDGING IN CALIFORNIA.
or in the gold-saving appliances ; but some of thera, such as hard bedrock, in eases are fatal to successful dredging.
The conditions bearing on the cost of operation are such that each tract of ground becomes a problem in itself, and any attempt to use the costs obtained under one set of conditions, on which to predicate those which wouH hold under another, mthout a thorough knowledge of the various elements which enter into the problem, will 16ad to large discrepancies between the results predicted and those actually obtained, with a possible consequent failure of the enterprise.
There have been built in California many dredges that have failed
and become total losses. Yet to-day, with all the data at hand for any careful investigator, there should be little excuse for failure. The varying conditions that exist where dredging is being done at Oroville, Folsom, in Trinity County, in Idaho, Montana, Colorado, British Columbia, the Klondike, Alaska, and New Zealand, both as to the digging of the gravel and the saving of the gold, give the miner the actual experience necessary for him to come to conclusions under most circumstances.
The illustration entitled "An Old Timer" illustrates one of the early mistakes in drec^e building in this State. This machine, on which
10 Gold Dredging In California.
some $40,000 was expended, is very odd, in view of later improved gold dredges. The bucket ladder is made of two pieces of 4-incli by 18-inch Oregon pine. The buckets are made of No. 14 iron; the links of %-inch by 2-inch tire-iron, and put together with ^/^-inch carriage bolts. It was driven first by steam and then by a gasoline engine. It is reported to have dug 8,000 yards in the period between March, 1902, and July, 1904. Its running time could hardly have been over one hour per day, being shut down almost constantly for repairs. It now stands idle in ground that dredged 30 cents per cubic yard. ' The single-bucket or spoon dredge was evolved in New Zealand in the early sixties, and was worked entirely by hand. A steam single- -bucket dredge was built in 1870. About 1880, bucket and ladder dredges were introduced. These were nearly all worked with power furnished by current wheels. The first steam chain bucket dredges of the present type were introduced about 1882. One dredge of this class, built about that time, was successfully worked for sixteen years. On account of the success of a dredge in 1889, on a branch of the Molyneux River, some twenty were built at an average cost of $17,500, but were failures, owing mainly to the fact that the ground was not suitable for dredging and the management bad. Many of these dredges were floated down to the Molyneux River, and under new ownership .were made successful. Then a number of suction dredges were built, but proved complete failures. Since then, the endless-chain bucket dredge, similar to those used in California, has held the field. In New Zealand, at the end of 1902, there were 201 dredges working, 52 standing, 23 building, 14 under removal, and 2 wrecked— a total of 292.
The first successful endless-chain bucket dredge in the United States -was built in 1894 at Gras?hopper Creek, in Montana. Many attempts to dredge had been made on the Pacific Coast, but it was not until 1897 that a dredge of the present type was builf in California. In the summer of 1895, W. P. Hammon and Warren Treat, who were interested in horticulture near Oroville, were working some gravels for gold on property now owned by the Feather Rive)- Exploration Company. Mr. Treat had made a pit about 100 feet square down to bedrock, using a centrifugal pump to keep the water out, and hauling the gravel in wagons out to small sluice-boxes, where it was washed. The gravel was handled several times by manual labor, and in spite of the heavy costs for labor and pumping water, there was a profit. Mr. Hammon had another pit, but on approaching bedrock found that the great amount of water coming in would make mining at a profit difiicult.
My attention was called to these cases and I visited the property, and, after consulting with Mr. Hammon as to the best process for working, suggested hydraulic elevators; but it was found, on investi-
U Ii
is
12 Ooi'D Dredoino In Caufornia.
gation, that the distance necessary to convey water and the large amount of water in the ground itself, to be handled, would make this impracticable- At that time little was known of dredging in California. However, I had purchased some of the laud through Mr. Hammon and A. P. Jones. A few months later I met, in San Francisco, Capt. Thomas Couch and F. T. Southerland, from Montana, who were looking for mining pr(q»erties. To them I sn^^ested the Feather River gravels, and there they went, and, with Mr. Hammon, after prospecting for about a year, purchased 1,000 acres, which is now beii^ worked by five dredges.
While they were prospecting this ground, R. H. Postlethwaite, a New Zealand engineer, who had come to California to look over the dredging field, had constructed, by the Risdon Iron Works, a 3^ cu. ft. bucket dredge, to be used near Smartsville, on lie Tuba River. While the dredge itself was satisfactory, the conditions did not permit of a financial success in working.
The first dredge at Oroville, built for the Feather River Exploration Company, began work March 1, 1898. It was designed by Mr. Postlethwaite, and built by the Risdon Iron Works. This dredge is still being successfully operated; it has been strengthened, however, in parts.
14 Gold Dredging In California.
Steam was used at first, but now all the dredges in the Sacramento Valley districts are worked by electric power. During the first two years of successful dredging at Oroville with endless-chain bucket dredges, a number of attempts were made to dredge with suction and other styles of dredges, but all these, with the exception of one steam shovel dredge, were failures.
Area Of Dredge Gravel.
The following table will show, in a general way, the acreage of gravel under consideration for dredging. It is probable that these figures will in many cases be increased and other districts opened :
Average Value per Cubic Yard, District. Acreage. in cents.
Yuba River _ ._ _. 5,000 25 to 30
Bear River 1,000 18 to 30
Folsom _._ 5,000 15 to 26
Calaveras _ _. 360 16 to 22
Stanislaus... _ 1,200 15 to 30
Trinity _- _ 1,000
Shasta : _ 1,500
Siskiyou ._ 1,000
Plumas - 1,500
Total _ 26,050
In Stanislaus County considerable prospecting has been done, and about 1,200 acres has been proved to contain values suflScient to warrant dredging.
In Shasta County, drilling is being done on Cottonwood Creek and on land opposite Redding on the Sacramento River, and on Clear Creek.
In El Dorado County some land on the South Fork of the American River, near Coloma, is being considered, but not yet reported proved.
In all these districts, and at other points in the Sacramento watershed especially, there are considerable areas of dredge gravel, most of which have been more or less examined, but not proved to be of suflRcient value to work at the present cost.
The best dredge authorities claim that by proving good grade of pay in some of this outlying ground and reducing working costs, at least 25,000 acres will in time be added to the fields which it is already decided to dredge in the Sacramento Valley.
In this connection experiments are being made with a view to working by a process similar to the present dredging system, but at much lower cost. Those interested do not care to give out any data at present.
Gold Dredging In California. 15
It may seem a simple thing, to those who know, to say that there is a great diversity in methods of gravel mining caused by varying conditions of the deposits, and that the method in vogue in one case may mean failure in another. Yet the want of this knowledge has been the cause of immense waste of capital. There have been large sums of money lost in trying to hydraulic drifting ground. Attempts have been made to use hydraulic elevators to work dredging ground, where there was an excess of water to be handled. Dredges have been built to work ground that could be worked only by means of hydraulic elevators. There are many thousands of acres of gravel, mostly lacustrine deposits, in California and other states and territories on the Pacific Coast and in Alaska that is free from water and should be worked with steam shovels, which people are now exploiting with a ^new to working with dredges. In other words, they are proposing to make a condition— by flooding the ground with water— -that means an unnecessary cost. A study of the conditions existing wiU lead to conclusions as to methods to be adopted; and in this way only can economic success be made.
The different kinds of gravel mining, it may be said, are :
i^irs^— Ordinary hydraulic mining, requiring water under pressure and a good dump, with gravel easily removable.
/Second— There are the drift mines in layers of gravel deposits over-capped with lava or other material of such great depth that only underground or drift mining is possible.
T^ird— There are the bars along the rivers, based on hard bedrock, that must be worked with hydraulic elevators for want of dumping facilities, and which can not be worked with dredges because the bedrock is hard. Yet, in these cases it must be understood that even hydraulic elevators are of no use if there is an excess of water.
Fourth— There is the gravel with an excess of water, with soft bedrock, that can only be worked with dredges.
It would be futile to hydraulic the lava-capped divides in Placer and other counties in California; yet this has been attempted. They must be drifted.
It would be impossible to make an economic success of the use of hydraulic elevators at Oroville or Folsom, on account of the excess of water in the gravel ; yet this has been attempted.
In some mountainous districts in California, dredges have been tried and have proved failures, because the bedrock was too hard to dig and the gold could not be lifted.
Then there are cases where the excess of water prevents the use of hydraulic elevators, and the hardness of the bedrock and the consequent conditions that usually follow prevent the use of dredges. Yet
16 Gold Dredging In Califobnia.
inventions not now known may be made to work these gravels at a profit.
Then again, there are large tracts of gravel, usually of lacustrine deposit, in the Sierras, not deep, and not overcapped with lava, that afford good opportunity for the use of steam shovels.
Geology.
While dredge mining is being conducted, under conditions apparently satisfactory to those engaged in the industry, in the Sacramento Valley districts of Oroville, Yuba, Folsom, and Calaveras, and on the Bear River, there is an interesting geological' feature worthy of more than a passing thought, and that is that all of this dredging is being done on what may be considered a superficial layer of gravel, under-laid by a stratum of volcanic mud and eand, the deposition of which, of course, antedated the deposition of this gravel.
The gold-bearing veins existed and were eroded for a great period of time, antedating the volcanic activity which is such a prominent feature of the Sierra Nevadas, and the ancient rivers deposited their gold-bearing debris upon the original bedrock, both within the limits of their rims and upon the floor of the great interior valley— the present valley of the Sacramento River— which at that time was a vast fresh-water lake.
Subsequently the volcanic activity resulted, in many instances, in filling the old gold-bearing rivers to the brim with a vast quantity of volcanic material, now recognized in the mud, tufa, and breccia overlying the ancient river channels, and, as a matter of course, this volcanic material was carried out into the estuaries, extending even into the lake itself to a considerable distance, and covering the previously deposited gold-bearing gravel. The subsequent uplift of the whole Sierra Nevada system has resulted in the exposure of these lake-beds along the eastern edge of the Sacramento Valley.
The subsequent erosion of modern streams, cutting through the original ancient river channels, and often into the underlying bedrock, with its complex system of gold-bearing veins, resulted in the formation of a later bed of gravel, which rests upon the volcanic sands and mud of the lake.
Doubtless this process has been repeated a number of times, and this point could be determined by drilling or by sinking shafts. But it is clearly evident that the present dredging is not in deposits of gravel resting on the true bedrock— the slates and schists which form the adjacent foothills— but in later, and, quite likely, less valuable gravel.
In many ancient river channels there are sometimes two or three gold-bearing strata, called by the miners ''leads,'* and the stratum
Gold Dredging In California. 17
of gravel on the bedrock is usually the richest, while the upper strata are relatively of less value in gold per cubic yard. There are, however, instances contrary to this, where one of the upper strata is of more ylilue; but this is due to local conditions, probably generally to the erosion of other preexisting beds of gravel. Why this principle should not be proved true in this lake is well worth considering.
Similar conditions have been found to exist in the Cariboo country in British Columbia, and in some of the mountain districts of California outside of the Sacramento Valley region.
The discovery, however, of good value in these lower str£(,ta might not lead to satisfactory economic results, because the expense of handling large bodies of water that might be encountered would handicap any venture in that direction.
Agriculture.
The question of reclaiming these lands for agriculture after they shall have been dredged is hardly worth discussing at present ; but, in course of time, as farming lands become more valuable, they could be leveled with scrapers run by electric power and then covered with soil hydraulicked in the foothills and run down by flume. In the meantime, however, a large proportion of the rocks will disintegrate and so make soil.
However, should these lands be reclaimed, their average value for agriculture would be much higher than it was before they were sold to the dredge companies. Some of them were unfit for cultivation and very little were worth more than from $15 to $35 per acre in the Oroville district, but probably as much as from $50 to $60 per acre in the Folsom district. A small proportion was covered with orchards and vineyards, and so was worth more. Yet, as much as $1,000 per acre was paid by the miners for some land about Oroville, and an average of about $100 per acre for the whole Oroville tract. In other words, the owners received from the miners from three to five times the value of their property for agriculture in this district.
Granting that these lands will never be reclaimed, it may be asked, is not their 'destruction a distinct benefit to the State? Take the Oroville district, for instance. The farm owners have received nearly a million dollars for their land. There have been built Over thirty dredges and several shops, at a cost of nearly $2,000,000, a large part of which has been paid in wages. Probably as many more dredges will be built before the tract is worked out. It is estimated that the cost of repairs and renewal of parts during the life of each dredge will amount to as much as the first cost. It would take twenty years with thirty dredges to work the tract, and this means the employment of at least 500 men, with families dependent upon them, to say nothing of the
18 Gold Dsedoinq In Caufobnu.
men employed in the bmiding of the dredges and in the shops. This means the payment, in wages, of over $1,000,000 a year, and a livelihood for two or three thousand people, if we include those dependent upon the wage-earners. From this tract will be produced in gold, to be added to the wealth of thp State, about $60,000,000.
Prom the dredging ground in the Sacramento Valley districts (estimated at 25,000 acres) which have been proved, and which it has been decided to work, there should be produced an average of 15 cents per cnbie yard; and if we allow a depth of 9 yards, the estimated
25,000 acres will produce $163,350,000 in gold, to be added to the wealth of the State.
Placing the average value of all this ground, both that which is and that which is not suitable for agriculture, at $40 per acre for that purpose, the loss amounts to no more than $1,000,000.
In connection with the question of reclaiming these drec^fing grounds, it may be mentioned that James H. Leggett, owner of dredges at Oroville, has begun some experiments by planting eucalyptus and olive trees on the rock piles, with a few spadefuls of earth at the roots of each tree, and they are thriving. In New Zealand, experiments with a view to making forest land of the dre%e ground are reported to be meeting with, success.
Gold Dbedgino In Caufobnia. 19
Yield For 1903.
The output in gold, in 1903, from all the dredges in California, according to the returns made to the United States Mint, was $1,475,749. The yield for 1902 was $867,665, showing an increase of $608,084 for 1903. The returns for 1903 were from 25 dredges in the Oroville district in Butte County, 3 dredges in the Folsom district in Sacramento County^ 1 dredge in Siskiyou County, 1 dredge in Trinity County, and 1 dredge in Yuba County. Of the total for 1903, $1,329,998 came from Butte County, meaning the Oroville district. There will be an increase for 1904 beyond the proportionate increase in the number of dredges, because the new dredges are of larger capacity and improvements have been made in the old dredges.
At the beginning of 1905 there were, in the Oroville district, 28 dredges; in Calaveras County, 1 dredge; in the Folsom district, 5 dredges; in Shasta County, 2 dredges; in Trinity County, 1 dredge; in Siskiyou County, 1 dredge; in Yuba County, 2 dredges; total, 40 dredges, as against 31 dredges for 1903. Some of the dredges worked only part of 1903, having been built during the year. Taking into consideration the increased average yardage of these dredges and the fact that a number of new ones will be in operation during part of the year, the yield for 1905 may be expected to be considerably more than double that of 1903.
The Dredge.
The continuous-chain bucket dredge is practically the only type that is in successful operation in the gravels of the Sacramento Valley districts. New Zealand, Montana, Idaho, Colorado, and Oregon, and it holds the field in gravel where there is an excess of water and where conditions are generally favorable for dredging. There are many differences in detail in the different dredges, but under favorable conditions, such as exist in the Sacramento Valley district, in New Zealand, in the States named, and in Alaska, the results obtained from* these dredges do not differ much except where the conditions are abnormal and difficult. The dredge in use is much like the ordinary continuous-chain bucket dredge used for other work, so far as the digging part goes, except that the size of shaftings and strength and weight of all parts are greatly increased. For gold mining it consists of a hull, a digger, screen, sluice-table and sluice-boxes, a stacker, a pump, amalgamator, and sometimes a sand pump^ with lines or lines and spuds to hold the boat in position, and separate motors for each part where power is required.
20 Gold Dbedoinq In Oalipornia,
Hull.— So far, in California, all the hulls are made of wood, but some dredges sent to Dutch Guiana have l>een built with steel hulls. This hull is rectangular in shape, with a slightly reduced width in the bow of the boat. As, practically speaking, all the parts of the machinery of a dredge are renewed during the life of the dre<^, it has been su^ested that steel hulls would give a longer life and more solidity ; but ao far none have been constructed, and probably will not be until there is a nearer approach to perfection of the machinery and a better knowledge is had of the limits of the capacity of the dredges,
for the tendency is to discard the smaller dredges and to build those of lai^r capacity.
To allow the digging ladder and its chain of buckets to descend to the bottom of the ground to be worked, the huU in the forward part is divided by an opening called the well, in which the ladder is moved up and down. The dimensions of the hull vary with the size of the buckets, as may be seen by reference to the accompanying folder of particulars as to dredgra. The hulls vary in width from 30 to 40 feet, in length from 80 to 120 feet, and in depth from 7 to 9 feet.
GflM nines.— Near the center of the hull there is a main gaimtry, to support the upper end of the di^ng ladder and the main drive of the
22 Gold Dbedgino In 0Ali7Obnia.
bucket chaiD. These have commonly been made of wood, but lately some have been constructed of steel plates. There is a stem gauntry to support the tail sluices, the conveyor ladder, and the spuds, if they are used.
Digger.— This consists of a ladder frame, built strongly of iron or steel, so that a chain of buckets may travel continuously around its length. On the best of these, mai^anese steel is used in the lips and bushings of the bucket, and on the ladder rollers. It has been found that a lai^e saving in cost of repairs, which is the main cost, and
ILL, No. 11. DETAILS OF BUCKET CHAIN, LATEST TYPE BUCYBUS DREDGE— BIGGS No, 2.
where future saving can be made in the cost of dredging, is in strengthening the wearing parts of these buckets and links. A reference to the tables of cost wilt show how large is the proportion of the cost of working caused by the breaking of buckets and other parts of the digger. However, this has been very much reduced since the first successful work was done at Oroville, and is being continually reduced as new dredges are constructed. The greatest improvements are now being made by the use of special steels and in the shape of the buckets. The bucket line is either what is called of a "close connection" or of an "open connection"; that is, the buckets follow each other on each link of the chain, or there are open links between the buckets. Wher-
Oold Dredging In California. 23
ever there are no large bowlders and the gravel is comparatively loose, there can be no question that the close-connected buckets, with less speed, will dig more ground than will the open-eoimected. As to the difference between the open-and the close-connected bnoket in hard ground, the question as to the greatest capacity has not been settled, but it is probable that the close-connected bucket will give more satisfactory results. However, where there are large bowlders, the open connection must be used, or the backs of the buckets will be jammed and broken. The close-connected buckets are run at a lower rate of chain speed than the opeo-cooneeted buckets, the former moving at the
rate of about 50 feet, or 18 to 25 buckets, per minute, and the latter at the rate of 60 feet, or 12 to 15 buckets, per minute. Yet, in hard ground the open-connected buckets are filled to their full capacity more often than are the close-connected buckets. In this connection it may be said that most of the newer dredges at Oroville and Folsom are equipped with close-connected buckets.
Owing to the greater weight of the close-connected chain of buckets and greater yardage handled, more power is required than for open-connected buckets. The following tables will give an idea of this difference :
ILL. No. IS. BUCYKU3
. BUCKET LINE IN OPERATION. LAVA BEDS DREDGE No. B.
Gold Dredging In California. 25
The different motors in the Oroville Gold Dredging and Exploration Company's 5-foot Risdon dredge are of the following capacities:
Horse-power.
Main drive 50
Stacker and screens _ 20
Sidelines and head lines 10
Ladder hoist _ 15
Water pump _ 40
Primer pump 3
Total 138
The average amount of horse-power used in the dredge was 90. No returns were made of the proportion of the full capacity of each motor used.
The following figures are given by the builders of the Bucyrus, close-connected, belt-conveyor, shaking screen dredges, as to the horsepower of the motors as built :
Dredge with 3 cu. ft. Buckets. Horse-power.
Digging motor _ 50
Winch motor _ 15
Screen and conveyors _ 20
Water pump _ ._ 30
Sand pump _ 30
Priming pump 3
Total — 148
Actual consumption, about 100 H. P.
Dpedge with 5 eu. ft. Buckets.
Digging motor __-75orl00
Winch motor _ _._ 50
Screen. __ __- 15
Conveyor 10 or 15
Water pump _ 50
Sand pump 30
Priming and clean-up _ _. 5
Total _ -- 235
Actual consumption, about 125 to 150 H. P.
Dpedge with 6 eu. ft. Buckets.
Digging motor _ __- 100
Winch motor _._ _ 30
Screen.- - _ 15
Stacker _ __ 15
Water _ 50
Sand pump __ 50
Total -- - 267i
Actual consumption, not known yet.
.26 Gold Dredging In California.
The following data have been given as to the actual consumption of power, as per report in L. J. Hohl's paper read before the California Miners' Association:
For a 3 cu. ft. close-connected bucket dredge, with shaking screen
and belt conveyor: Horsepower.
Main drive _ _. 26 to 45
Stacker and screen _ _ _ - - 12 to 16
Water pump _ 45 to 60
Winches, maximum - _• 28
Sand pump 32 to 50
For a 5 cu. ft. dredge of the same type : *
Main drive - 42 to 70
Stacker and screen __ 10 to 20
Water pump... - -- 60 to 75
Winches, maximum - 27
Sand pUmp, not tested.
For a 6 cu. ft. open-connected bucket dredge, with revolving screen and bucket conveyor :
Main drive -._ 60
Water pump _ -. 62
Other motors, not tested.
Yuba dredge, 6 cu. ft. buckets, close-connected, with shaking screen and belt conveyor. This dredge digs 60 feet deep :
Main drive 108
Water pump ._ 68
Sand pump _ - 63
Stacker 9
Shaking screen 11
Auxiliary supply -- -- 13
Buckets.— The buckets at Folsom, Oroville, and Yuba vary in size from 3 cubic feet capacity up to 8^^ cubic feet, and it is proposed now to build a dredge at Folsom with buckets of 13 cubic feet capacity. They vary considerably in shape, and in the material used, but some of the best are those that are made with a cast nickel steel bottom piece, with sheet steel hood and manganese steel lips, and reinforced cutting edges. If a comparison could be made as to the breakage and consequent extra cost between the earlier buckets made and those now being turned out, a great advance would be shown, and greater advances are possible. This is a matter for the consideration of the manufacturers and the engineers in charge of the plants.
As to the difference in cost of operating under favorable and similar conditions with the different sized buckets, it may be said that the cost for labor is nearly the same for the anall as for the large dredge, and much smaller per cubic yard for the larger; that there is a proportionately smaller cost for power and for repairs. Management and all other expenses are reduced in the larger dredges, pro-
, Open-Connected Buckktb, Ribdon Type, 6 Cu. Ft. Capacity.
30 Gold Dredging In California.
vided, of course, that in their construction there is given, by the strengthening of the parts, as little loss by breakdowns. Then, it may be said, that the larger buckets will handle larger bowlders and so decrease the breakage in the bucket line. The parts being heavier, it is possible to dig harder ground. The increased yardage handled will mean a decrease in the interest cost on the original investment. As against this, it may be said that the first cost is much larger, and that better equipped repair shops are required.
The weakest portions of the bucket bottom are the eyes and the parts coming in contact with the manganese or nickel steel wearing plates of the upper and lower tumblers. As these wear there is an increase in danger of breakage, and it is to the manufacturers that we must look for remedies in this respect, by the addition of more metal to add strength and compensate for wear, by improvement in the character of the steel used, and by changes in the faces of the tumblers in order to give better bearing and reduce the strain. Simpler and stronger parts of the best materials must be used to remedy the present evils.
Spuds and Head Lines,— Ho keep the dredge in place, move it about, and hold it against the bank, there are two methods in use: (1) Two spuds, one of steel, and one of wood at the stem of the boat— the wooden spud being used when the steel spud is lifted and it is desired to **walk" the boat ahead. At the forward end of the boat are two steel-wire rope lines faj^tened to the shore to move the boat to right and left through an arc of a circle, and two at the stern. (2) Instead of spuds and lines, five lines are used — two at the stern, two forward, and one ahead to hold the boat against the bank.
In the lighter and softer ground in New Zealand, the guy method seems to be preferred, but in Oroville both methods are in vogue.
Where the surface of the ground is level, and the ground to be dug is soft and shallow, some of the dredge owners prefer the lines. An uneven surface of the ground, hard gravel or deep gravel makes the spuds preferable. Most of the largest operators in Oroville equip boats with both, but use the head line only in emergencies. When using guys only, the digging must be done only from the bottom ; while with the spuds the bank may be cut in terraces, and this is sometimes preferable in deep ground.
In deep ground when cutting the bank by digging from the bottom up in terraces, or down, there is less danger of injury to the bucket line and cleaner lifting of all gravel if spuds are used. This means that there would be less loss of pay gravel caved down behind where the digger is working, and less loss of time and consequent
32 Oold Dredqins In Califobnu.
lese loss of capacity in yardage. However, several operators state that with a head line instead of spuds in digging deep ground, the drei^e may be moved more quickly in case of heavy caving of the bank, and so save accidents. Then, again, the use of the head line gives on easier and more even distribution of the tailings, and, it is claimed, makes tiie sand pump unnecessaiy.
ILL. No. 19. TAILII«» STACKER, BELT CONVEYOR.
The Stocfter.—There are two types of stackers in use in California — cne the ordinary belt conveyor, and the other an endless chain of buckets. (See 111. Nos. 19, 20, 21.) Usually, the Bucyros dredges, and other makes except the Risdon, are equipped with belt conveyors, while the Risdon is equipped with bucket conveyors. The belt conveyor will not work at a higher grade than 18 or 20 per cent, while the bucket conveyor works usually at 35 degrees. The belt of the former must be renewed every six or nine months. This makes the cost of
Gold Dredoino In Caupoknia. 33
"repairs" considerably more than for the bucket conveyor. However, to offset this, there is considerably less loss of time with the belt conveyor from this cause, for practically the only wearing part is the belt, and when this wears out, a new one can be put in in a few hours. Some of the tables of loss of time and cost of repairs of conveyor give figures so that comparisons can be made, but hardly enough data have been kept to figure closely on the differences.
ILL. No. JO. TAIUNGS STACKER, BUCKET CONVEYOR.
In New Zealand a number of dredges equipped with centrifugal stackers are in use. It is claimed for them, that the original cost is less, that the weight saves several tons on the boats, that the cost of repairs is less, and that the efficiency is as great as for the belt and bucket conveyors. However, none have been built in California and no d^nite data are at hand.
ILL. No, 21. CONTINUOUS-BUCKET aXACKING LADDER ON " EL DORADO No. 1
Driven Bv Independent Motor In Small Motor House On Top Of
Ladder. Latest Type Risdon Dredge
1, Orovillk, Showing Sand Pump Working.
Gold Dredging In California. 35
Sand Pumps.— In order to prevent the filling up of the basin in which the dredge floats and consequent interference with its flotation, in many cases at Oroville it has been found necessary to pump the fine tailings that come from the sluice-box up to the top of the rock pile made by the stacker (see 111. No. 22). As this requires confiiderable power, it is discarded wherever possible. In deep ground with deep water, it is not required.
Screens, Sluices, Etc.
The conditions that are most important to be considered in order to determine the kind of appliances to use in saving the values are: (1) Size of particles of gold; (2) Shape of the particles, whether nuggety or flaky; (3) Presence of clay; (4) Will the gold amalgamate readily; (5) Amount of black sand; (6) Amount of platinum; (7) Hardness of gravel.
Screens.— Two kinds of screens are used in California: the shaking and the revolving. The purpose is to disintegrate the gravel and clay in order to permit the fine material, the values and water to pass through the holes along the length of the screen to the gold-saving tables or sluices below, and convey all coarse material to the stackers, to be carried to the dump piles. As to screens, two main questions must be determined: (a) Whether to use a revolving or a shaking screen; (6) Size of holes in the screen.
As to (a), the hardness of the gravel, and the presence or absence of clay are the main determining features. If the gravel is a clean wash, comparatively free from clay, such as that at Oroville and Folsom, the shaking screen is generally preferred to the revolving screen, mainly because the first cost and the cost of repairs are less. However, there are cases, even in these districts, when some hard pieces of gravel are not disintegrated and the values lost. In case there is any -clay present, it will adhere to the gravel or pieces of bedrock, especially if blocky, or will *'ball up" and so carry off the gold. In a shaking screen, bowlders and larger pieces of bedrock will not be turned over «o that the water jets will have free play. This is the case especially in such bedrock as most of that along the Yukon, which is often blocky, and carries much gold in clayey seams down to a depth of from one to •six feet. Where the gravel is hard, it has little opportunity to disintegrate in the length of the shaking screen. A revolving screen with flanges and rods across the screen will turn the material over and over, subjecting all sides of it to the force of the water from the jets, and will afford a sort of milling process by which" the bowlders and smaller
38 Gold Dredging In California.
stones are lifted up and thrown down on the lumps of gravel and clay.
Under the favorable conditions existing in the Sacramento Valley-districts, the shaking screen is preferred for the following reasons: (1) The effective screening surface is larger; (2) It is easier kept in repair, because the plates are small and conveniently replaced; (3) The gravel drops over a larger surface on the plates below, and so comes the better in contact with the quicksilver. Then the water from the jets playing down on the screen plays over a wider and thinner surface.
In some cases, a combination of the revolving and shaking screens would be preferred. In this way two screenings could be had.
The revolving screen varies in diameter from 3i/^ feet and in length ujp to 24 feet. The shaking screen for a 5-foot bucket dredge is in some of the later dredges built in two parts— the first part 7 feet wide and 16 feet long, and the second or lower part, 7% feet wide and 16 feet long. This enables, of course, a much larger sluicing-table space to be employed below the shaking screen. , The size of the holes in the screens will be determined by the size of the largest particles of gold. At Oroville and other districts in the Sacramento Valley, where all the gold is fine, five-sixteenths and three-eighths inch holes are generally used. Where there is both coarse and fine gold, it must be remembered that with the ' larger holes, coarse material will have to be sluiced, a greater depth of water will be required in the sluices, and there wiU be a consequent greater loss of fine gold. To obviate this, it is suggested tliat smaller holes be used in the upper part of the screen and larger holes in the lower part, and that the finer and coarser material be run into separate sluices. It would not be necessary to have the larger holes in more than four feet, or even less, of the length of the screen.
Sluices,— On the dredges in the Sacramento Valley districts, such as Oroville, Yuba, and Folsom, the gold is saved on what are called gold-saving tables (see 111. Nos. 24 and 25) and a sluice running out astern of the dredge where the tailings are dumped into the water. The area of these tables is for a 5-foot dredge with shaking screen about 750 square feet and for the sluices about 300 square feet^ and somewhat less with revolving screens. This area is somewhat less for the smaller dredges and more for dredges of larger capacity. As it is, generally speaking, all the surface possible is made, and it is limited, of course, to the size of the boat. There can be no question but that much of the finer gold is lost. How much this may be has not been determined, for, no matter how careful the rocking and panning of the drill samples, the finest gold is not saved.
"I
40 Gold Dredging In California.
It may be said that if some of the finest gold saved at Oroville were shaken up in a bottle of clear water it will take two hours' time to settle again. Therefore, neither panning, nor rocking, nor any of the present gold-saving devices can save all the gold. One of the best informed men at Oroville, who has been in the industry since the beginning, says that, with the improvements that may in time be made in the gold-saving appliances, it would be possible to save more gold in the dredges than could be shown by the most careful and exact sampling with pans and rockers.
In most cases at Oroville and Folsom, the tailings are sampled in order to determine how much gold is being lost. But this sampling is of no value except to show that the sluice-boxes and tables save a large per cent of what could be found by panning or rocking. In other words, very little is fou^d in the tailings, and in most cases practically none at all, by panning or rocking.
The quantity of fine gold which goes off in the water should be determined by test, and if it amounts to as much as seems probable, there should be devised a scheme, in connection with the sand pump, for an auxiliary saving appliance that would enable a larger proportion of the finest gold to settle. The amount of extra power that would be required and the cost of extra equipment need not be much. Of course, the larger the dredge, the greater the opportunity to save larger proportions of the gold now being lost.
There are two classes of sluice and table paving used in the Sacramento Valley gravels to save the fine gold. One is ordinary Hungarian or cross riffles with quicksilver, and the other cocoa matting covered with expanded metal, 2%-inch mesh. These are nearly equally satisfactory, so far as the managers report. However, in most cases each manager has used only one kind and made no comparison. Where comparison has been made, the preference seems to be in favor of the riffles with quicksilver. There is no arsenic or anything else present to prevent a rather free amalgamation. Yet there is present so much black sand which would prevent the gold from reaching the quicksilver that it is found necessary, in putting in the riffles, to iiLsert between them stones that stand up above the tops of the riffles in order to stir up the black sand and allow the gold to go to the bottom. On the cocoa matting, the expanded metal, in diamond shape, about one-fourth in(5h deep, is placed for the same purpose.
One of the most careful managers at Oroville states: "We originally used cocoa matting on our dredge, but later installed the riffles and quicksilver and increased our gold-saving area 85 square feeft, by utilizing the space in the distributing box directly under the
Gold Dredging In California. 41
screen. We are going to use riflBes and quicksilver in our new dredge.''
Under the screens on the first tables quicksilver in large quantities held in place by riffles is used with a view to bringing the fine gold into contact as it drops from the screens. In this respect, shaking screens do better work than revolving screens, because they let the fine material down over a larger surface.
Both at Oroville and Folsom, and even at Yuba, it has been found that gold— even the very finest gold— if brought in contact with the quicksilver will amalgamate without much difficulty. In Colorado and in Idaho, where there is fine gold, and dredging has been done on rather an extensive scale, it has been found impossible to make any consequential saving of gold with quicksilver, owing to the presence of arsenic or something else. The result is that cocoa matting or some similar appliance must be used. It would appear that where the very fine gold amalgamates freely, riffles and quicksilver are preferable to cocoa matting.
As platinum does ndt amalgamate with quicksilver, there is a greater loss of this metal when riffles and quicksilver are used, than when cocoa matting and expanded iron mesh are used.
Crew Of A Dredge.
The following table will give an idea of the number of men commonly required on dredges. The wages named are those usually paid at Oroville:
Crew fop One Dredge. per Day.
1 foreman, at $5.00 per day |6 00 — |5 00
3 winchmen,at|3.00to$3.50 per day _ 9 00 — 10 50
Boilers, at|2.00to |2.50perday - 6 00 — 7 50
1 blacksmith, at |3. 50 per day 3 50 — 3 50
1 helper, at $2.00 to $2.50 per day 2 00—250
2 Chinamen, at $1.75 to $2.50 per day _ 3 50— 5 00
Total $29 00 —$34 00
In addition there is a superintendent, whose time is generally divided among several dredges. The winchmen and oilers work eight-hour shifts, while the blacksmith and helper work ten hours. The Chinamen clear the ground of brush and trees, '*bury dead men,'' as making fasteners for the lines is called, and do general chores.
The depth to which the present dredges may dig is from 30 to 60 feet below the water-level, the latter depth being reached by the new dredges on the Yuba.. That greater depths may be reached is only a question of increased strength and power and longer digging ladders. These work at their best, it is claimed, on an angle of 45 degrees.
42 Gold Dredging In California.
Working Costs.
A majority of the dredge companies in California have given statements as to the approximate actual cost of dredging per cubic yard, which will be found in the accompanying folder, and in tables following. These costs vary from 2.36 and 3 cents to as much as 8^^ cents. It will be seen that where a return of 3 cents or less is given, it is for a new dredge with all the advantages of the latest ideas as to strengthening the parts of the machinery, and that there have been no breakdowns and consequently very little, if any, costs for repairs. The labor bill has been very light, for the running time has been full. The owners of this dredge have stated that their .costs will be materially increased in working longer periods of time, through the loss in actual working time caused by breakdowns and the cost of new parts and for repairs. "^
So it is only those reports on dredges which have been in operation for a long time, say three or four years at least, that are of much value in determining what would be the average cost of working under similar conditions. However, one must remember that the lately built dredges are more strongly made and afford less opportunity for breakage and repair costs. The record for low cost is 2.36 cents per cubic yard with a new dredge, as will be noticed in the tables of cost given elsewhere in this bulletin.
In studying these reports, one must consider in respect to the different districts: (1) The cost of power; (2) The rate of wages; (3) Whether the company reporting has one or several dredges under one management; (4) Whether the company has its own machine shop or not; (5) The hardness of the ground, and this particularly as to whether blasting with powder is necessary; (6) The size of the buckets; (7) Whether the buckets are alternating or dose-connected; (8) Whether belt or bucket conveyor is used; (9) Whether revolving or shaking screens are used; (10) Whether a sand pump is used; (11) The age of the dredge.
Only one company operating at Folsom returns cost of working, and that at 5 cents. At Folsom the cost for power is 0.65 of a cent per kilowatt hour, while at Oroville it is iy2 cents.
Some idea of the difference in cost per cubic yard between operating one dredge and operating several dredges under one management may be had from the estimate of the Oroville Gold Dredging and Exploration Company, and this comparison table, showing the estimated cost of one or three dredges, all under one management. (See tables.)
Of course, under certain difficult conditions a dredge of small capacity may be preferable, but under most ordinary conditions, such as at Oroville, Folsom, and other places in the Sacramento Valley,
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Gold Dredging In California.
the greater the yardage capacity of the dredges, the lower the cost of working.
It may be said that the cost of repairs is still excessive, but this item of expense has been reduced from year to year since the first successful dredge was put in operation in 1898. It may be said, too, that if the dredge-builders had not increased the strength of the buckets, the quality of steel used, and in many other ways strengthened all the straining and wearing parts of the dredges, it would now be impossible to build, as they propose doing at Folsom, a dredge with 13 cu. ft. buckets, or even 7 cu. ft. buckets. A comparison of costs of a new dredge with those of an old dredge of the same size and type is therefore unfair.
Whenever the Bucyrus type of dredge is mentioned, it is understood to have close-connected buckets, a shaking screen, belt conveyor, and riflSes and quicksilver on the sluicing-tables; while the Bisdon .dredge has alternating buckets and links, a revolving screen, bucket conveyor and cocoa matting, with expanded metal mesh covering them on the sluices. It may be said, however, that the makers provide for the mine owners whatever style of any of these parts they may require.
It is for the dredge-builders and for the skilled managers at Oroville or FoLsom or elsewhere in the State to more seriously consider this question of cost of repairs than anything else, except, of course, the question of saving the present loss of fine gold, which is far greater than most of them suppose.
The following tables (Nos. 1 to 8) are from the annual report of the Oroville Gold Dredging and Exploration Company of San Francisco, for the calendar year 1903 :
TABLE No. 1— BULLION TABLE.
Month.
Operating Expenses.
Cost
per
Cubic
Yard.
January... February..
March
April
May
June
July
August
September.
October
November. December .
Totals and averages.
Cents. 5.52 5.98 9.47 5.46 6.33 7.83 7.52 8.44 5.34 5.05 6.42 5.45
* In January, February, and March, 44,680 cubic yards of soil were dredged on moving dredge to block 196.
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46
Gold Dredging In California.
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Gold Dredging In California.
47
Table No. 2 does not include :
Bullion expense 04
Taxes and insurance 38
San Francisco general expenses 17
A total of 0.59 to be added to make up the total of the summary of costs in cents per cubic yard, in Table No: 4.
TABLE No. 3— EXTRACTION TABLE.
Month.
Co
Cd 9
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<P Ob
I-
O
Character of Ground Dredged.
January _ -j
February
March ■!
April
May
June
July
August J
September.
October _
November
December
Totals and averages
L03 0.87 0.94
20,850 G. ;) 10,150 S. !f 30,130 S. 4,400S. 26,170 G. 49,130 35,900 34,040 40,100 46,000 46,790
6
pr. ct.
Cents.
58
71
70
70
94
77
65
43
74
1
f^ iS9' Soil and tight eravel containing clay. Soil.
Soil and loose gravel.
Soil and loose graVel.
Soil and loose gravel.
Soil and loose gravel.
Soil and loose gravel.
Soil and loose gravel.
Soil and loose gravel, worked bv Chinese.
Sand and nne gravel.
Sand and fine gravel.
Some Chinese tailings.
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48
Gold Dredging In California.
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Gold Dredging In California.
49
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Gold Dredging In California.
Average Amount Dredged per Day of 24 Hours
Average Amount Dredged per Day of Running Time
Total Dredging Time
Total Lost Time...
Other Causes
Clean-ups
Lines
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Gold Dredging In California. 51
TABLE No. 7— SUMMARY OF COST, 1903.
One Dredge. Three Dredges.
Dredge crew, power, and operating supplies _• . 2.52 2.52
Repairs — Labor _ .93 .48
Supplies- 2.65 2.58
Total operating costs 6.10 5.58
Superintendence _ .38 .16
General expense — Oroville. 28 .09
San Francisco .17 .06
Taxes and insurance _ .38 .24
Bullion expense .04 .04
Grand total all costs .._ 7.36 6.17
The cost for the same dredge for 9^ months in 1904 (January 1 to October 15) was:
Amount dredged (bank measurement) 378,890 cu. yds.
Cost per cubic yard —
Power ..._ _ 1.01 cents
All supplies 1.88 cents
Total __ _ 5.71 cents
This does not include about 0.59 of a cent to be added for general expenses, which would bring the total up to 6.30 cents, as against 7.35 cents for 1903.
The above work was done with one 5 cu. ft. bucket, close-connected Risdon dredge, with revolving screen and bucket conveyor. It was the intention of the company to build two more dredges. However, one larger dredge is now being built, with the view of handling, with the two, 100,000 cubic yards per month, at a cost, as estimated, of 5.71 cents per cubic yard.
52 Gold Dredging In California.
Since the above was written a record has been made with the new Bucyrus dredge, '* Biggs No. 2," of the Oroville Gold Dredging and Exploration Company, which shows a cost considerably below any other similar work in the State, as far as known. In tabulated form the results are shown as follows:
TABLE No. 8— RECORD OF NEW BUCYRUS DREDGE, BIGGS No. 2.
For 31 Days, from For 30 Days, from
February 26 to March April 1 to April 30, 30, 1905, inclusive. 1905, inclusive.
Possible dredging time 31 days 30 days
Lost time _ 119 hours 18 min. 149 hours 55 min.
Average actual dredging time per day 20 hours 9 min. 19 hours 00 min.
Total amount dredged (bank measurement) 102,630 cubic yards 109,630 cubic yards
Amount dredged per day _ 3,310 cubic yards 3,654 cubic yards
Operating costs per cubic yard—
All labor 1.16 cents .82 cents
Power --- _-- _ .39cents .82 cents
All supplies .81 cents .37 cents
Other expenses .. _.. 1.34 cents
Total 2.36 cents 3.35 cents
As to the two following tables from Oroville companies, the general manager says: ''We have not been running the Bucyrus machine a year's time in ordinary diggings, and I am obliged to send you a record of our machine of the Bucyrus type which has been running in very extraordinary ground, and some of the heaviest digging in the Oroville district. This, of course, decreases the capacity of the machine and increases the cost of handling, but it is just as well to have some data from the harder places as to have all conditions favorable, especially for general information that might lead to investment." In this case the use of powder increased the cost.
It will be noted that the Eisdon dredge has open-connected buckets and a bucket conveyor, while the Bucyrus has close-connected buckets and a belt conveyor.
Gold Dredqing In California.
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Gold Dredqing In California,
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56
Gold Dredging In Caijpornia.
The following table of costs applies to a 3^^ eu. ft. close-connected bucket line dredge. For the first month the cost was increased by expense of organization and management prior to commencement of operations, the company proposing to place under the head of cost of operating all expenses (including insurance, taxes, and office) except the original cost of the ground and the dredge. In April, the high water caused a shutdown. An entire new bucket line purchased and on hand, and a 40-horsepower motor to replace the first motor of 30-horsepower for the pump, considerably increased the cost.
TABLE No. 11.
Per Cent
of Time
Operated.
Cost
per Cubic Yard.
Labor.
Repairs Power. and
, Supplies.
General Expense.
Total Expense.
December
January
February
March
cents. 3.82 3.06 2.76 2.50 3.92 3.22 2.34 3.15 2.35 3.05 2.97 2.70 2.85
cents. 2.21 1.73 1.99 1.81 1.70 2.38 1.75 1.96 1.31 L90 2.29 1.99 1.75
cents. 1.30 2.76 1.14
cents.
cents. 11.36
April
May .. .
June
July
August -.-
September
October..
November
December
Average per mo.
The following table of loss of time is for the same dredge during the first twenty-two months of working from December 1, 1902. The figures are averages of hours lost per month:
TABLE No. 12.
Cause of Stoppage. Hours. Per Cent.
Stepping ahead 11.29 8.1
Ladder and bucket line... _.. 34.60 24.9
Stacker 5.80 4.1
Winches 2.90 2.1
Screen.. 6.20 4.5
Water pump 56 .4
Sand pump 5.40 3.9
Lines _. 2.40 1.7
Power __ _... 26.00 18.7
Other causes _ 36.20 26.0
Clean-up ._ .. 7.80 5.6
Total -._- -_ _ 139.16 - 100.0
In addition there was lost some time while the power was oflf, and some through floods. The average amount of material handled for the
twenty-two months was 39,900 cubic yards per month. The main
Gold Dredging In Califobnia.
57
saving in time was made by putting new eastings in the bucket line earJy in 1904.
The following figures of costs are for a new 3 cu. ft., close-connected bucket dredge, with shaking screen and belt conveyor, at Oroville. They show how costs increase as parts wear out. These expenses include office, secretary, and all expenses in full:
TABLE No. 13.
December 1, 1902, to June 1, 1903.
June 1, 1903, to June 1, 1904.
Material dug _ __
Average per month.
Per cent of working time
Payroll
Power
Dredge supplies
Taxes and insurance
Sundry expenses
Maintenance and repairs
Total cost
Total Expense.
Cents per Cubic Yd.
Total Expense.
Cents per Cubic Yd.
!
The following figures are from the r«eport made to an Oroville company for the year 1903, of a dredge that began operations November, 1902. The bucket capacity is 5 cubic feet, close-connected, shaking screens and belt conveyor:
TABLE No. 14.
Working days in year _ _ _. 363
Working hours in year _ _ _ 8,712
Power was off — hours 389.66
Possible working hours _ 8,322.33
Total hours machine was digging through year _ __ _ 5,710.58
Percentage of total hours digging 65.5
Percentage of possible hours digging ___ _ 68.6
Surface area worked otit— acres _ -.. 13.297
Average depth of cut _... 24.55
Cubic yards handled t... 526,680
Cubic yards handled per day ._ _ 1,450.909
Cubic yards handled per digging day 92.228
Cents per Cost of Dredsring— Cubic Yd.
For labor 2.593
For power _ __. 1.744
For supplies _. ... .441
For shop repairs and parts _ 2.360
For freight _ 162
For general expense and boarding-house loss. .142
For clearing land _. _ .156
Total cost at dredge 7.698
58 Gold Dredging In California.
Total Cents per
Other Costs (Administration, Taxes, Insurance, etc.)— Expense. Cubic Yd.
San Francisco office, management and traveling expenses. ._ $4,229 66 0.803
Taxes 663 15 .126
Insurance ._- ._. 529 75 .100
Total administration, etc _.. $5,510 55 1.046
Add costs at dredge, as above 40,033 14 7.598
Total costs, all included |45,543 69 8.644
The following gives the cost from January 1 to September 30, 1904
(nine months), of a 5 eu. ft. connected bucket Risdon dredge, with
bucket conveyor, at Oroville. As the company operates five dredges,
some of the costs are less than they would be for one dredge under one
management:
TABLE No. 16. Cents per
Total. Cubic Yd.
Power . $3,116 35 .8796
Labor operating '. 5,016 04 1.4157
Supplies 90 13 .0254
Repairs 9,623 63 2.7161
Office 1,036 47 2926
Incidental -. 874 31 .2468
Teaming 276 56 .0781
Total number of hours run, 5,100.
Total number of cubic yards dredged, 354,311.
The following table gives the cost of operating, for the first six months, Leggett No. 3— a new Risdon 5 cu. ft, open-connected bucket dredge, with revolving screen and bucket conveyor.
This, of course, is the case of a new dredge, where the cost of repairs and replacing of parts has been very light; it amounts to not more than one fourth of the repairs of a similar dredge worked by the Oroville Gold Dredging and Exploration Company— an older dredge, however, and probably not as strongly constructed as was this.
TABLE No. 16.
Total quantity of ground handled 315,165 cu. yds.
Average depth of ground _-_ 30 feet.
Cost of power, at 1| cents K. W. hour.. _ _ $4,241 97
Cost of labor _ -.-. 4,250 00
Cost of management . 900 00
Cost of water -._ -_ 460 00
Cost of repairs __ - - 1,929 37
Cost of supplies - 722 42
Total cost _ _ $12,493 76
Average running time per day, 20 hours 8 minutes. Sufficient lost time on account of lack of power to make a total of 21 hours per day. Average cost per cubic yard, 3.94 cents.
The following figures are taken from Mr. L. J. Hohl's paper, read before the California Miners' Association. He states that they will
Gold Dredging In California. 59
give a fair representation of the extremes of cost per cubic yard at Oroville :
TABLE No. 17.
Power 1.06 1.20 1.15 1.61 1.77
Repairs _ 2.86 3.03 3.46 2.97 3.80
Labor ._._ L64 1.32 1.85 2.33 2.05
General expenses 64 .67 1.23 1.28 .73
Total - 6.-20 6.72 7.69 8.19 8.35
In the following case, the running time, on the basis of 365 days in the year, was sixteen hours in the twenty-four. It will be observed that a large percentage oi the loss was caused by floods in the Feather River. This, of course, is an extreme case. The figures are for a 5 cu. ft. close-connected bucket dredge. The tumbler loss was owing to not having tumblers on hand:
TABLE No. 18.
Causes of Stoppage. Per cent.
Belting _ L3
Bucket line _ _. .- _-. 23.1
Lines breaking, and changes _. 4.8
Cleaningup-- _ ._-_ 1.7
Conveyor __ _.. .-. 5.3
Elevating machinery.- -. 1.5
Frictions and winches __ 2.5
General repairs _ ___ _ 1.7
High water 15.6
Holidays _._. _ _._ L8
Ladder and ladder-hoist. 1.3
Oiling _ 3.8
Power off . 4.5
Shaking screen ___ 4.5
Stones, roots and stumps _ __ ___ ._ 0.7
Upper tumbler _. 16.2
Water pump , _ 1.4
Total __ _ __ _.._ - 100.0
The following monthly averages are given as one year's work on three Risdon dredges of different capacity, but all with alternate buckets, revolving screens, and bucket conveyors:
TABLE No. 19.
Average Time Run per Month.
Size of Buckets.
Age of Dredge at End of Year.
Cubic Yds. Dredged per Month.
Cost per Cubic Yard, in Cents.
575 hours. 538 hours. 558 hours.
3 cu. ft. 5 cu. ft.
4 cu. ft.
5 years. 3 years. 18 months.
Gold Dredging In Calipornia.
Prospecting And Examination Of Conditions.
It may seem a simple thing to' say that a careful study of all the conditions should be made before a dredge is ordered, no matter how large the values in gold may he found to ie. The values may in many cases be of almost minor importance, or of no importance, where, as is the case in some of the mountain districts, the hardness of the bedrock, with much of the gold on the bedrock, has prevented dredging very rich ground. There have been many failures in California, and all because proper examination of the ground was not made before the dredges were built.
In Trinity County, in one case, a dredge was put in and failed and has been dismantled because the fact that the ground was valueless was not proved. There is another case where a dredge was built and operated for a time on very heavy ground, b'lt it was so weak in construction that it failed and was dismantled. Now another company is building a dredge to work the same ground, with every promise of success. There are similar wrecks in the Oroville sea caused by incompetent pilots.
It has been said in regard to sampling, that which will apply to any other part of the examination of a dredging property: ** Haphazard and occasional sampling and assaying are worse than useless. They lead to great losses of valuable capital, frequently to the total abandonment of good properties, and, worse than all, to a false sense of satisfaction that discourages improvement by denying its necessity."
Conditions to be Considered.— The following are some of the conditions, etc., to be determined by drilling and other examination prior to determining whether the ground may be dredged, prior to estimating costs, and prior also to determining the kind of dredge to be used:
Value in gold per cubic yard, and its dis- Whether bedrock is level or not.
tribution. Water — amount; of supply, and cost.
Hardness of gravel. Cost of power.
Total depth of gravel to bedrock. Wages.
Depth of gravel from water level to bedrock. Cost of transportation .
Whether level or rough on surface. Cost of supplies.
Size of bowlders. Cost of repairs.
Amount of clay in gravel. Cost of land.
Hardness of bedrock. Climatic conditions.
Hardness of Gravel.— QenersMy speaking, any gravel that may be picked may be dug with the dredge, without the use of powder. If it is so hard as to require blasting, the cost per cubic yard will be increased from 2 to 3 cents.
Depth of Oravel.—The most satisfactory depth to dredge with some of the newer dredges now in use is not to exceed 60 feet, but they will
Gold Dredging In California. 61
work down to 70 feet. In order to work to a greater depth than 70 feet, some changes in the digger, stacker, and power would be required.
Level Surface of Gravel.— With an uneven surface the use of headlines is not so satisfactory as spuds.
Size of Bowlders.— Very large bowlders can not be handled with the ordinary dredge, and much gravel may be left on the ground. The size of the bowlders must be considered also in deciding whether to use an open or close connection of buckets in the digger, the latter rendering it impossible to handle the larger bowlders.
Climatic Conditions.— Oi course, freezing weather will prevent washing the gravel, and cause a stoppage of work. In the northern latitudes of Montana and Alaska, the season is commonly not more than five months long.
Clay in Gravel.— The clay will not permit of clean dumping from the buckets, and not only is nwich gold carried back to the bottom and lost, but the yardage capacity of the dredge is decreased. Besides this, the clay carries off gold and fine amalgam from the sluice-boxes.
Hardness of Bedrock.— li the bedrock is too hard to dig, gold in the crevices or lying near the bedrock is lost. The drill will locate the position of the pay which may not be too close to the bedrock.
Level Bedrock.— The bedrock should be near enough level to permit the boats to float over all the ground to be worked.
Presence of Arsenic.— The presence of arsenic or anything else that wi]l prevent free amalgamation makes the iise of quicksilver and riflSes of little avail, and cocoa matting, plush, or other such means must be adopted to save the gold, especially where it is in fine particles.
DnWin^.— Nearly all this work in the Sacramento Valley districts of California has been done with Keystone driDs, No. 3 traction. Owing to the presence of water in the gravel in most instances, it has been found impracticable to sink shafts. The cost of the drill, including freight, etc., is about $1,900 complete. Three men are required to work it, with wages from $3.50 to $4.00, and $2.50 and $2.00 per day. To this must be added the cost of fuel, water, repairs, etc., and wages of one or two men to do the sampling. The sampling, if properly done, would require a skilled man, and his pay might add much to the cost. The total cost per day to run the drill and do the sampling varies from $15 to $30. About 12 or 15 feet per day is a good average speed for sinking in the gravels of the Sacramento River basin. With larger bowlders and harder ground the cost might be materially increased.
^ In comparatively shallow ground, where there is not much water, it is much more economical to sink shafts than to drill, and the results will be found more satisfactory.
By proper sampling is meant the determination, from a comparatively small sample, of the values in a much larger volume of the same material. Care, judgment, and experience are necessary, and all such work, whether done by drilling or by sinking shafts, should be put in charge of an experienced man. Gravel lifted by drills or taken from a shaft must be accurately measured or weighed, and proper allowances made for expansion when loosened. Allowance must be made for excess of bowlders not sampled, and for excess of gravel beyond the normal width of the drills that may come in and be lifted.
Prospective/.— There is no rule as to the number of holes that should be sunk. More drill holes would be required, to give satisfactory results, than shafts. If the values are comparatively evenly distributed over the tract to be examined, fewer holes would enable nearer approach to a correct estimate of values than where the pay is uneven. In districts where the character and values are comparatively well known in parts of the gravel that have been sampled, less careful exg-mination is necessary on intervening tracts in order to determine most of the conditions and even the values.
Errors in Sampling frequently occur from the squeezing in of material around the bottom of the casing^ so that more gravel than is called for by the size of the hole is lifted. A check on this is to drill and pump in a section of a foot or so and weigh the material. Sliming and consequent loss of gold sometimes result when too long a period. of churning transpires before pumping the hole.
The casing should be kept driven below the point of drilling, whenever possible.
Fine Gold.— When the gold is as fine as at Oroville or Folsom, the pan and rocker will not save all of it, but will save all that the best saving tables in the dredges will save, and may save considerably more. But when it is considered that if some of the finest gold now. being saved be shaken up in a bottle of clear water it will take one or two hours to settle, there can be no question that some is lost whether the sampling is done by panning or rocking, and also in the sluicing. How much this is could be determined by gathering samples, especially of the water from the pans and rockers and also at the ends of the sluices and subjecting them to proper tests. It would seem that this work should be undertaken and carefully carried out by the dredge people. If much gold is being lost, there is a spur to ingenuity in devising means for saving it.
Gold Dredging In Califobnia.
So// o--*-
Jvs.
Pay
Gray*/
Coarse
Gravel 3/ -Mi' Bedrock
So// 0-3'
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3-ia
S-/0'
Wafer I eve/
Coarse Grot's/
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Coarse Grave/ t
Coarse Grave/ s-f'-a
Sand B»'-3i Bec/rocif
Fine Grave/
Pay
Graye/ ts -s.
Bee/roc/i
Gold Dredging In California.
65
The following tables show the form in which notes of the sampling have been kept in making an examination at Folsom:
Column marked "a" indicates colors of fine and flour gold, smaller than "b" size. Column marked "b" Indicates colors of size estimate 25 to 1 cent. Column marked "c" indicates colors coarser and heavier than "b" size.
Appil 11, 1904— Hole No. 1.
No. of
Material.
No. of Colors.
R.pmn.rk4
Feet.
"b"
Surface line. Sand and gravel.
2
1 pan.
6
Loose gravel.
6
6
1
1
Hole 4J ft. 6 p. M.
April 12, 7:30, started 2 pans.
Loose gravel.
30
8
2
5 pans.
Loose gravel.
15
4
Rockered.
Bedrock.
10
No water, rockered.
Total _
63
18
2
Qeneral Remarks: Drilled 14 feet in the clay, being a volcanic ash ; first few feet a light brown color, then whitish, down as far as we drilled. This clay is called "bedrock."
Diameter of drill, 5| inches; diameter of shoe, 7 inches; casing, 5| inches, inside diameter. '
66
Gold Dredging In Caxjfobnia,
4.
No. of
Material.
Nc
>. of Colors.
Remarks.
Feet,
"b"
"c"
Surface.
Sand.
Sandy gravel.
6
1
Sandy gravel.
10
1
1
Sandy gravel.
10
1
Gravel.
5
2
Sand and gravel.
15
5
1
Coarse sand and gravel.
10
3
Fine mica.
Sand.
Gravel— yellow.
10
6
1
•
Gravel — compact.
15
6
2
6 p. M. -April 16th.
27
1 Gravel— compact.
15
4
•
Gravel— compact.
75
10
Gravel — compact. Bedrock.
75
6
Total
21
•
General Remarks: Cubic feet of hole, 8.82. Weight of gold, 2.85 grains; value of gold, 11.4 cents. Value per cubic yard, 34.85 cents.
Gold Dredging In Oalifornia.
•f./roR
y
67
Appil 22,
7.
No. of
Material.
No. of Colors.
Remarks.
Feet.
"a"
"b"
"c"
Surface. Fine sand.
4
Sand and gravel.
8
1
Sand and gravel.
10
Not rockered out. 6 p. M.
Gravel.
8
1
■
Gravel and sand.
16
1
1
Water line, 14 feet.
Gravel and sand.
15
1
1
Gravel and sand.
16
4
Small gravel and gray sand — soft.
26
2
1
27
Sand and gravel.
60
5
2
Compact gravel. Cobbles.
60
3
Coarse sand and small gravel.
16
10
3
6 p. M., Sunday, April 24th.
Brown gravel, yellowish
brown water.
Bedrock.
10
1
Totf
il
29
8
General Remarks: Cubic feet of hole, 9.62. Weight of gold, .95 grains ; value of gold, 3.8 cents. Value per cubic yard, 10 cents.
Per actual measurement we took out of hole No. 7, 6.703 cubic feet. By using pipe factor for 7-inch hole we figure, or estimate, 9.62 cubic feet, making a difference of 2.917 cubic feet in our favor. The actual dirt taken out is for a pipe 5J inches in diameter and 7-inch shoe.
OOIiD DBEDOINO Dt OAUFOBNIA.
DREDGE-HINING DISTRiaS OF CALIFORNIA.
Oroville District.
In this district was made the second discovery of gold in California— about two months after Marshall made his discovery at Sutter's mill in January, 1848. In March, General John Bidwell, while encamped
ILL. Ho. 31. GENERAL VIEW OF THE OEOVILLE DREDGING DISTRICT.
on Feather River, at Hamilton Bend, a few miles below the present town of Oroville, on his way to his ranch from Sutter's Fort, heard of Marshall's discovery. He decided to prospect, and soon found that gold existed. In May of that year the first camp was started at Morris ravine. At first the mining was done above Oroville in the creeks and on bars in the rivers in the moontaiiiB, but by 1856 there were many hundreds of white men working in the present dredging field. The richer spots, some at considerable distance from the river, were worked, but the places of these white men were soon taken by Chinese, who swarmed over the flat ground. It is estimated that by the later seventies there were over 7,000 Chinese working, almost entirely with
Gold Dredging In California.
maDual labor, in these grounds. Although little work was done below the water level, which was always a number of feet above bedrock, large sums of gold were produced. One of the present dredge companies says that in working over some ground that had previously been exploited by the whites or Chinese in earlier days, they recovered not over half the values recovered from adjoining ground. Much of the ground in this district was worked by whites and again by the Chinese, and now is being worked for the third time with dredges.
The yardage handled by the larger dredges with ten men is as much as would require 500 men or more by the old methods.
There are seventeen companies in the Oroville district, operating 28 dredges. Of these, 27 are of the continuous bucket type, and one of the shovel type. The total amount of holdings of these companies is 5,343 acres. In addition, there are about 2,000 acres held by individuals which have been proved good dredging ground and will probably be mined. Besides this, there is considerable ground of lower grade that may pay to dredge as the costs of working shall be reduced. Most of this is fai-ther down the Feather River beyond the present fields, but of similar
70 Gold Dredging In California.
material. The total cost of building the 28 dredges was about $1,550,- 000. In addition, machine shops, drills, oflScee, etc., would make the total outlay for equipment up to the present time nearly $2,000,000.
The gold yield from the 25 dredges operating in this district in 1903 was $1,329,998, according to the United States Mint reports.
Prospecting,— FrsLCtieaUy all the prospecting of these gravels was done with drills, there being too much water in the ground to permit the sinking of shafts.
Values.— The gold is comparatively evenly distributed in this district, and the best informed make a minimum estimate of the average values for the whole 7,500 acres of 17 cents per cubic yard. Taking the depth of the gravel at 10 yards, this would make the probable yield a little over $60,000,000.
Gravel.— The depth of the gravel varies from 26 to 42 feet, and will average 30 feet. It is comparatively loose, a clean wash, practically free from clay, and contains practically no bowlders large enough to interfere with digging. In the present river channel and adjacent ground there is no need to blast the banks, but in some of the higher ground it has been found advisable to use powder.
Bedrock.— The false bedrock to which the gravel is dredged is comparatively flat and quite soft, being merely a bed of volcanic tuff carrying other gravels, and may be dredged to suflBcient depth to take up all that bears gold.
Poii;er.— Electric power is used in all cases, at a cost of 1% cents per kilowatt hour.
Water.— An excellent ditch system supplies water in all parts of the district. The cost averages about $125 per month.
Labor.— Good, experienced labor is easily obtained, the daily wages being usually, for foremen, $5 ; winchmen, $3 and $3.50 ; other laborers, generally $2.50. Some Chinese are employed, at $1.75, to do general work.
Transportation, Supplies, etc. — Rail facilities are convenient, the source of supplies not distant, and there are well-equipped shops for repairs.
Gold.— The gold is comparatively fine, there being no nuggets, and 20 per cent of it will pass through a 150-mesh screen. However, it easily amalgamates. The value is about $18.50 per ounce.
Ideal Conditions.— Tsiking all things into consideration, the conditions are almost perfectly ideal for successful dredging.
Area Worked.— There has been dredged since March 1, 1886, when the first dredge began work, 605 acres.
Gold Dredoino In Caufornia.
Companies Opebatino.
Feather River Exploration Company, John J. Hamlyn, manager, Oroville. In Sees. 24 and 25, T. 19 N., R. 3 E. Area of holdings, 850 acres. This company installed the firat successful dredge ever operated in California, designed by R. H. Poetlethwaite, and built by the Risdou Iron Worha. "Work was begun March 1, 1898. Prior to that, extensive work had been done in prospecting and examining the property. The first dredge was of 3 cu. ft. bucket capacity, and the company has since constructed four 5 cu. ft. bucket dredges of the Risdon
type. The capacity of these latter is 40,000 cubic yards per month, each dredge consuming 63 horse-power. Revolving screen and cocoa matting and expanded metal screens are used. It is important to note that this company makes returns, for about five years' work with these dredges, of a cost of 6 cents per cubic yard. In this connection it should be considered that there are no less than five dredges under one management, and that the ground in which they are working is not as hard as is some of the Oroville gravel. The extent of ground worked is 150 acres.- The company contemplates building additional dredges. (See 111. No. 33.)
Front End Of A Dipper Dredge.
Gold Dredging In California. 73
Lava Beds Dredging Company, J. W. Goodwin, president, San Francisco. In Sees. 19 and 30, T. 19 N., R. 3 E. Area of holdings, 700 acres. This company began work in 1900, and has two dredges at work, of 5 cu. ft. bucket capacity, Bucyrus type. The extent of ground worked is 25 ac?*es. The company returns as the average approximate cost of dredging, 8 cents per cubic yard. (See 111. No. 35.)
Oroville Gold Dredging Company, F. S. Mayhew, secretary, San Francisco. In Sec. 25, T.-19 N., R. 3 E. Area of holdings, 66 acres. This company operates one dredge of the Marion steam shovel type, which has been working since February, 1901, and which has dug since then 20 acres of ground. The cost of the plant is $45,000. The digging capacity of this dredge is returned by the owners as being from 18,000 to 24,000 cubic yards per month. It is valuable to note in this case that the horse-power consumed is only 40. The owners make no returnfi as to the cost of dredging per cubic yard, but claim very satisfactory results. (See 111. No. 36.)
Central Gold Dredging Compa^iy, F. S. Mayhew, secretary and manager, San Francisco. In T. 19 N., R. 4 E. Area of holdings, 150 acres. Began operations in May, 1904. This company operates one Bucyrus type machine, with capacity of 40,000 cubic yards per month. The bucket capacity is 3 cubic feet. The gravel is 30 feet in depth. The details of the machine are shown in table of dredge data accompanying this bulletin.
Indiana Gold Dredging and Mining Company, 0. C. Perry, manager, Oroville. In Sees. 13 and 18, T. 19 N., R. 4" E. Area of holdings, 175 acres. This company began operations July 1, 1901, and has two dredges at work, each of 3 cu. ft. bucket capacity, of the Bucyrus type, built at a cost of $50,000 each. The horse-power consumed on these dredges is 100. The actual average digging capacity of these dredges is returned at 42,000 cubic yards per month. Forty acres of ground has been worked. The owners return the cost of working at 7% cents per cubic yard. (See 111. Nos. 37 and 38.)
Kia Ora Gold Dredging Company, R. H. Postlethwaite, president, San Francisco. In Sec. 3, T. 19 N., R. 3 E. Area of holdings, 153 acres. This company began work in May, 1899, and has dredged 40 acres with one dredge, of 3^ cu. ft. bucket capacity, of the Risdon type. The gravel is of an average depth of 28 feet, which is considerably less than the average of the district. This company returns as the cost of working 4 cents per cubic yard, and gives the capacity of the dredge at 31,800 cubic yards per month. (See 111. No. 39.)
7g
Gold Dredging In California.
Cherokee Gold Dredging Company, L. J. HoW, manager, Oroville. In Sec. 3, T. 18 N., R. 3 E. Area of holdings, 200 acres. This company began operations in October, 1902, with a Bucyrus dredge of 5 cu. ft. bucket capacity, and has worked 16 acres of ground. The cost of equipment, including a machine shop and a pumping station, was $80,000. The company contemplates building another dredge. The horse-power consumed on the dredge is 120, and the company makes return of cost of working at 7 cents per cubic yard. (See 111. No. 40.)
Pennsylvania Dredging Company, Sam W. Cheyney, manager, San Francisco. In Sec. 25, T. 19 N., R. 3 E. Area of holdings, 152 acres. This company began operations in October, 1902, and has worked 25 acres. Its dredge was built by the Golden State and Miners' Iron Works of San Francisco, with buckets of 5 cu. ft. capacity. The average horse-power consumed is 140. The cost of the dredge was $70,000. The average number of cubic yards dug per month during the year 1903 was 43,830. The cost of dredging is returned at 8^^ cents per cubic yard. This dredge has a different system of screening from the others in the district, in that there are two screens used, one above the other, of the shaking screen type. In the upper screen the holes are 1^ inches in diameter, and in the lower screen ^ inch in diameter. (See 111. Nos. 41 and 42.)
Butte Oold Dredging Company, B. Noyes, secretary, San Francisco. In Sec. 7, T. 19 N., R. 4 E. Area of holdings, 85 acres. This company began operations November 26, 1902, and has worked 15 acres with one Bucyrus dredge, of 3^ cu. ft. bucket capacity. The cost of the dredge was $50,000. The horse-power consumed is about 80. The actual average digging capacity of the dredge for the first thirteen months of its operation was 47,640 cubic yards per month. The owners return the average cost of the digging and all other expenses at 7 cents per cubic yard.
American Gold Dredgirig Company, F. S. Mayhew, secretary, San Francisco. Area of holdings, 275 acres. The company began operations in November, 1902, with a 3 cu. ft. Bucyrus dredge, and has since built a 5 cu. ft. bucket dredge of the same type. The digging capacity of the 3 cu. ft. dredge is returned at 45 cubic yards per minute. The return of the actual average dug by the 5 cu. ft. bucket is 90,000 cubic yards per month for the first six months, and the cost of digging during that period, including all expenses, such as oflBce, management, etc., is placed at 3 cents per cubic yard. These figures are, of course, unusual both as to the yardage and as to the cost per cubic yard. The
80 Gold Dbedoin6 In California.
company was reluctant to give out these figures unless it would be stated that during the sis months' running there were no breakdowns, and consequently no cost for repairs ; also, that there was so little loss of time that this lai^e yardage was made possible. The cost of the 5 eu. ft. dredge was $70,000, and the average of the horse-power consumed, 100.
EI OrO Dredging Company, B. Noyes, secretary, San Francisco. In Sees. 17 and 20, T. 19 N., E. 4 E. Area of holdings, 220 acres. This company began operations in December, 1903, and has worked five acres. Its dredge was built by the Link Belt Machinery Company, of
Chicago, with buckets of 5 cu. ft. capacity, close connected. They claim an average capacity of 75,000 cubic yards per month. In respect to screens, sluicing table, and stacker, it is similar to the Bucyrus type. The company proposes to build another dredge. (See 111. No. 43.)
James E. Leggett, Oroville. In Sec. 18, T. 19 N., R. 4 E. Area of holdings, 70 acres. Mr. Leggett began operations March 31, 1904, with a Risdon dredge of 5 cu. ft. bucket capacity. He returns the average digging capacity as 45,000 cubic yards per month. The horae-power is placed at 100, and the approximate average cost of dredging per cubic yard at 5 cents. Five acres have been worked. (See lU. No. 10.)
82 Gold Dredging In Caupoenia,
Viloro Syndicate, Limited, J. W. Pew, secretary, San Praneiaco. In Sees. 19 and 30, T. 19 N., R. 4 E. Area of holdings, 200 acres. This company began operations November 1, 1904, with one dredge of the Bueyrus type, 5 cu. ft. bucket capacity. As theyhave only lately begun work, no returns as to capacity are available. (See III No. 44.)
Orov'Q.le Gold Dredging and Exploration Company, C. H, Munro, manager, OrovlUe. In Sees. 24 and 25, T. 19 N., R. 4 E. Area of holdings, 600 acres. This company began operations in April, 1902, with a Risdon dredge of 4 cu. ft. bucket capacity, and in 1905 also started
working a new Bueyrus dredge (Biggs No. 2) with 5 cu. ft. buckets. This latter dredge has a record of 109,630 cubic yards dug for thirty days from April 1st to April 30th inclusive. Details of the work and its cost are given elsewhere in this Bulletin, as are details of sizes, etc., of both dredges. The very full tables of costs of operations were prepared by Mr. Munro. " (See III. No. 11.)
Boston and OrovUle Mining Company, William P. Hammon, manager, Oroville. In Sees. 13, 23, and 24, T. 19 N., B. 3 E., and Sees. 17 and 18, T. 19 N., R. 4 E. Area of holdings, 650 acres. This company began operations in July, 1901, and has worked 100 acres of
Gold Dredging In California. 83
ground. Three dredges are operating, two of the Risdon and one of the Bucynis type, each of 5 eu. ft. bucket capacity. The cost of equipment was $175,000. Revolving screens are used in the Rladon dredges, and shaking screens in the Bucyrus. However, in all these dredges Hungarian riffles and quicksilver are used in preference to docoa matting and expanded metal. It will be seen that this is also true of the dredges owned by the Boston and California Dredging Company and indicates the preference in the district for riffles and quicksilver over the cocoa matting, and a belief that where there is no arsenic or other material to prevent the free amalgamation, the riffles and quicksilver
1LL.N0.«. VILOBO DREDGE, OROVILLE FIELD. LATEST TYPE OF BUCYRUS DREDGE.
■will save more of the fine gold than will the matting. The company proposes to build additional dredges, (See 111, Nos. 45 and 46.)
Boston and California Dredging Company, William P. Hamtnon, manager, Oroville. In Sees. 18 and 19, T. 19 N., R. 4 E. Area of holdings, 300 acres. Operations were commenced in March, 1902, and about 60 acres of ground have been worked. The company is operating three dredges, all of different types— one being a Risdon, with open-connected buckets and a bucket conveyor ; one a Bucyrus dredge, with close-connected buckets and belt conveyor, and the third a Marion Steam Shovel Company dredge, with continuous chain buckets, similar to
86 Gold Dredging In Caupobnja,
those On the others, close connected. The management's returns of the digging capacity of these dredges are: for the Risdon, 45,000 cubic yards; for the Bueyrus, 60,000 cubic yards; and for the Marion, 90,000 cubic yards per month. It may be stated here that if it were not that the dredges were built in the order named, so that the last built had advantages over the others in stronger construction, there would not be so much difference in the yardage bandied. Then, again, it may be said in favor of the Risdon dredge that the horse-power is less. However, it may be said in regard to the Marion that the company claims that the construction of the screen enables the washing of larger
quantities of gravel than do the other screens, and in this way permits a larger amount of gravel to be handled. A number of the managers at Oroville have stated that the sluicing capacity or the gold-saving capacity of the dredges was not sufficient to handle all the gravel that might possibly be raised. The screen on the Marion dredge is of the revolving type, somewhat conical in shape, growing smaller with offsets toward its outlet. These offsets, together with crossbars, retard the progress of the gravel sufficiently to insure perfect washing. However, the washing capacity, it is claimed, was increased fifty per cent. (See 111. No. 47.)
r VIKW OF MARKiOLI* COMPANY'S DRKDfiK AT OROVILLE.
88 Gold Dredging In Califobnia.
Marigold Dredging Company, J. W. Goodwin, president, San Francisco. In Sees. 30 and 31, T. 19 N., R. 4 E., and Sees. 25 and 36, T. 19 N., R. 3 E. Area of holdings, 467 acres. Operations were commenced on this property in January, 1900, with a 3 cu. ft. bucket Risdon dredge. This company is now operating one 5 cu. ft. Bisdon dredge. The extent of ground worked is 50 acres. (See 111. Nos. 48, 49 and 50.)
Feather Valley Gold Dredging Company, C. Jackson, manager, San Francisco. In Sees. 4 and 5, T. 18 N., R. 3 E. Area of holdings, 220 acres. This ground was lately purchased and was drilled.
Yuba District.
In this district no dredging was done until August, 1904. The two dredges built by the Yuba Consolidated Gold Fields Company are doing contract work for the Government retaining dams. They are thus making their tailings of value. There is only one company actually operating, but other lands have been drilled and it is estimated that there are 5,000 acres of gravel suitable for dredging
Prospecting,— This was done with drills.
Values.— The gold is comparatively evenly distributed over the district. Estimates place the values at from 15 to 35 cents per cubic yard. As the gravel is much deeper than that in the Oroville district, a very rough estimate, without much data to go on, of the probable total yield of this district would be $50,000,000.
Orav eL— The depth of the gravel in this district is greater than in any other in California, the Yuba Consolidated Gold Fields Company digging to a depth of 60 feet. It is a loose, clean wash, free from clay, and contains no large bowlders. The dredges in operation use close-connected buckets.
Bedrock.— The false bedrock to which the gravel is dredged is comparatively flat and very soft— a volcanic ash, with sand doubtless overlying other gravels.
Power.— 'Electric power is used.
Lahor.—The wages paid on the dredges are $4 for winchmen and $3 for laborers. Higher wages are paid than at Oroville, in order to obtain more efficient men for larger and more expensive dredges.
Transportation, Supplies, efc— Rail facilities to Marysville are good, and a better wagon road is being built to the tract.
ILL. No. 60. STACKER END OF MARIGOLD COMPANY'S DREDGE AT OROVILLE.
Gold Dredging In Calipoenia. 91
Gold.— The gold is very fine. As much as 20 per cent will pass through a 150-mesh screen. It readily amalgamates, the dredge using riffles and quicksilver. The value is about $18.50 per ounce.
Ideal Conditions.— VrsiCticaUy all the conditions are ideal for sue-
%
cessful and economical dredging.
Yuba Consolidated ' Gold Fields, Newton Cleveland, manager, Marysville. In T. 16 N., R. 5 E., ten miles east of Marysville, on the Yuba River. Area of holdings, 3,000 acres. This company began operations in August, 1904, and has a contract from the Federal Government for building a retaining dam at that point. Two dredges of the Bucyrus type of 6 cu. ft. bucket capacity are now at work. The company has contracted for four more dredges, and a number of others are contemplated. The cost of the two dredges now in operation was about $200,000. Shaking screens, Hungarian riffles with quicksilver, and belt conveyors are used.
It is notable that in this district these dredges are digging to a depth of 60 feet, which is more than 50 per cent greater than the depth of the gravel in the other Sacramento Valley districts. These dredges, which are new, are lifting 90,000 cubic yards per month each, with 200 horsepower. (See 111. Nos. 51 and 52.)
Bear River District.
Area.— About 1,000 acres of gravel on the Bear River near Wheatland have been drilled systematically and proved of sufficient value to dredge.
Gravel.— The depth of the gravel averages about 30 feet. It is all a clean wash, free from clay and with no large bowlders.
Bedrock.— This is volcanic ash, similar to that at Folsom and Oroville.
Power. — There is electric power available, at a cost similar to that at Oroville, namely, 1^/2 cents per kilowatt hour.
Wages.— For winchmen and laborers, this will be about $3.50 and $2.50 per day respectively.
Transportation, Supplies, e^c— There are convenient rail facilities with San Francisco, and the neighboring farming country is a source of supplies.
Gold.— The gold is comparatively very fine, twenty per cent of it impalpable, and in value about $18.50 per ounce.
92 Gold Dredging In California.
Conditions.^ All the conditions are as favorable as those at Oroville, and very similar.
Bear Biver Mining Company, subsequently called Bear River Exploration Company, R. D. Evans, Boston. Location, near Wheatland. Area of holdings, 1,000 acres. There are four Risdon dredges, two of which began operations in July, 1900, and the other two began in 1902. The first two have 3i/4 cu. ft. buckets, and the last two 4 cu. ft. buckets. The latter have a capacity of 50,000 cubic yards per month. The gravel runs from 40 to 50 feet in depth, and has some clay with it. Details of dredges are given in the large table accompanying this Bulletin.
Folsom District.
There are in this district five companies operating eight dredges, none of which use less than 5 cu. ft. buckets. The largest dredge has buckets of 13 cu. ft. capacity. Starting later than the operators at Oroville, they have made use of what has been learned there, and discarded all small dredges. The work is in the hands of people with plenty of capital and skilled engineers. One of the companies has a i^machinery plant larger than any other in California, outside of San Francisco, and is prepared not only to do ita own repairing, but also* to build its own dredges. This, of course, means a large saving of cost in repairing, and it indicates how companies with large areas to . be worked and many dredges employed may very largely reduce the cost of dredging.
Area,— The Folsom district, as it is called, extends from the town of Folsom to a short distance below the Fair Oaks bridge along the American River, a branch of the Sacramento, and in Sacramento County a distance of six miles, or a little more. Most of the gravel is on the south side of the river, and is in width, generally, from 1 to iy2 miles. The area of the gravel that has so far been acquired by the company^ after investigation, is about 5,000 acres.
Prospecting,— 'PrsLCticaUy all the prospecting of these gravels has been done with drills, there being too much water in the ground to permit the sinking of shafts.
Values,— The gold is comparatively evenly distributed over the district, and the results of the drill samples indicate that the gravel will average from 15 to 25 cents per cubic yard. Taking the depth of the gravel as 10 yards, this would make the probable yield over $10,000,000.
Oravel,—The depth of the gravel is from 16 to 50 feet, and in this respect varies more than does that at Oroville, because it is not spread
GOLD DREDGINiB IN CALIFORNIA. 93
over as wide an area. The average is about 30 feet. The gravel is all a very clean wash. In this connection it may be said that shaking screens are used instead of revolving screens in all except one dredge. There are no large bowlders to interfere with digging, and it may also be said that with the exception of the one dredge, all the buckets are close-connected. Except on some of the higher benches, where there is cement, there has been no need to use powder for blasting.
Bedrock,— The bedrock here, as at Oroville, is a volcanic ash, or false bedrock, which may be dug without difllculty, and under which there is probably other gravel overlying the real bedrock.
Pot(;er.— Electric power is used in all cases, at a cost of 0.65 of a cent per kilowatt hour. This is against ll^ cents per kilowatt liour paid at Oroville, or less than one-half— an important consideration in the working costs.
Wa^er.— There is an abundance of water, supplied at low rates.
Labor.— Experienced labor is easily obtained, the wages being usually $5 for foremen, and $3 and $3.50 for winchmen. Other laborers are paid from $2 to $2.50.
Transportation, Supplies, e^c— There is a railroad into the district. The source of supplies is San Francisco and Sacramento, with low rates of freight.
Gold.— The gold is comparatively very fine in size of particles, and the size of holes in the screens is usually three-eighths of an inch, as at Oroville. The mint value of the gold is about $19 per ounce.
Conditions.— Tsking all things into consideration, the conditions are ideal for economic working.
Agriculture.— l>^ot over one-half of the 5^000 acres of dredging ground in the Folsom district is of any value for agriculture. The value of the rest of the ground could not be placed at more than $100 per acre, or a total of $250,000 for the whole tract. The yield in gold from this district will exceed $40,000,000, according to the estimates of values made. The value of this gold to the State at three per cent per annum would amount to more than four times as much each year as the total value of the ground for agriculture. Then, of course, it may in time be reclaimed for agriculture, as lands of that character become more valuable.
Debris. So far there has been no dredging in the river and no jdebris whatever has been, sent down by these dredges. In time, the river bed may be dredged, but, as at Oroville, this can be done without detriment.
Gold Dredging Ik Caufornia,
Companies Operating.
The Ashburton Mining Company, Robert E, Cranston, manager, Sacramento. In Sees. 5, 6, 7, and 8, T, 9 N., R, 7 E., American River District, Sacramento County. Area of holdings, 310 acres. This company began operations March 1, 1899, with a dredge that was burned S[ay 25, 1903. Its new dredge, made by the company at a cost of $120,000, of the Bueyrus type, has not been long in operation, but the cost per cubic yard for working is estimated at more than 5 cents. Another dredge will be built. The area of ground worked is 20 acres. (See III. No. 53.)
E Of Bihdon Boat.
El Dorado Gold Dredging Company, E. H. Benjamin, secretary, San Francisco. In T. 9 N,, R. 6 E., and T. 9 N., R. 7 E., American River District, Sacramento County. Area of holdings, 550 acres. This company has prospected its ground with drills and is now operating a Risdon 7 cu. ft. bucket dredge. Began operations April 25, 1905, (See 111. No. 54.)
Colorado-Pacific Gold Dredging Company, O, B. Perry, manager. In T. 9 N., R, 7 E. Area of holdings, 200 acres. Has two dredges, the first of which began work in April, 1899, and the other in 1902. Both are of the Eisdon type ; one with buckets of 3^ cu. ft. capacity.
98 Gold Dredging In Campornia.
and the other 5 cu. ft. The smaller machine has a capacity of 35,000 cubic yards per month; the large one averages 60,000 cubic yards per month. This company is working in hard ground, for which reason one dredge is being rebuilt. (See 111. No. 55.)
Folsom Development Company and Syndicate Mining Company. (Both companies under one management.) [All information, even in such simple matters as capital stock of corporations, acreage of holdings, etc., refused by the manager— the only instance of the kind in the State. LEwas E. Aubury, State Mineralogist.] (See 111. No. 56.)
Calaveras County.
So far there is being exploited and considered in this county one small tract of ground, which is described in 'the following paragraph, and at present no other lands in the county are being considered with a view to dredging.
Calaveras Gold Dredging Company, C. M. Derby, manager, Jenny Lind. In T. 3 N., R. 10 E., M. D. M., on the Calaveras River. Area of holdings, 350 acres. This company began operations in February, 1904, with a Bucyrus dredge of 5 cu. ft. bucket capacity. Electric power is used. The cost of the plant is $75,000. Wages are $3 for winchmen, and $2.50 for laborers. The average depth of the gravel is 35 feet, and it is a clean gravel wash, free from clay, with a few large bowlders. The bedrock is a volcanic ash similar to that at Folsom and Oroville. About 8 acres of ground has been worked.
Plumas County.
In Plumas County, so far as prospecting has developed, about 1,500 acres of dredging ground has been proved.
Shasta County.
There are^two dredges at work in Shasta County, both near Redding, and described in following paragraphs. The holdings of these two companies amount to 1,096 acres. Along Cottonwood Creek and its tributaries are large areas which are being considered, amounting to 3,000 or 4,000 acres. Some drilling has been done, but very little of this area has been proved of value. The gravel in the Cottonwood country and the bedrock are similar to that at Oroville, although the gravel is generally shallower. On Clear Creek an additional 2,000 acres is being considered. (See 111. No. 57.)
No estimates of values were given by the Shasta owners except by the Detroit and California Mining Company, who report a recovery of from 25 cents to $1.50 per cubic yard in Clear Creek.
As to power, it may be said that the Huron Submarine Mining and Construction Company uses steam, with crude oil for fuel, at a cost of $3 per horse-power per month, while the Detroit and California Mining Company uses electric power at a coat of $5 per horse-power per month.
Huron Submarine Mining and Co7istruction Company, G. A. DuBois, \J manager, Redding. In Sec. 25, T. 32 N., R. 5 W. Area of holdings, 396 acres. This company began operations in the Sacramento River, three miles above Redding, and opposite the mouth of Middle Creek.
The average depth of the gravel is from 8 to 25 feet. It is blue gravel with many bowlders. The gold is coarse and well worn, and worth about $19 per ounce. The bedrock is of igneous series, very rough. The dredge is unique, having neither buckets nor shovels. It was built by the company on its own plans. The boat is 65 feet long, 24 feet wide, and draws 2 feet of water. A 75-horsepower engine operates a rock pump, air compressor, and auxiliary machinery. Oil is used for fuel at $1.17 per barrel, making the cost of power about $3 per horse-power per month. At the center of the boat is a steel shaft made with sections for extending to any required depth. Each section is boat-shaped. 8 feet wide, 6 feet high, and lli/^ feet long. (See Illnstra-
100 Gold Dredging In California.
tions Nos. 58 and 59.) The sharp end of these sections heads up stream, thus cutting the water. The lower sections are cylindrical, the lowest being provided with a water-tight door for ingress and egress of divers. This shaft is sunk through water and gravel to bedrock gravel, 25 i'eet deep being worked in November, 1904. Down the shaft extends the 10-inch column of the rock pump, and a 2-inch rubber hose to convey water under 100 pounds pressure to the mouth of the pump column. A diver in the shaft with the hose in hand works with freedom, directing gravel to the mouth of the pump, and with the pressure cleaning the gold from crevices. The capacity of the pump is 1,500 cubic yards per day, and sufficient water to wash the gravel in the sluices. The divers receive $125 per month, working five hours each day, and can remain under water that length of time without coming to the surface. The cost of the plant was $110,000. Four men are required for a crew. The company estimates the cost of dredging at 3 cents per cubic yard. They express an intention of building, another dredge of a larger size.
Detroit and California Mining Company, T. K. Heintz, president and manager. Redding. In Sec. 36, T. 31 N., R. 6 W., and Sec. 31, T. 31 N., R. 5 W. Area of holdings, 700 acres. This company was organized and began operations in the summer of 1900 on a flat in Clear Creek canon, which formerly had been a lake-bed. The bedrock at present laid bare is a false one, under which probably other gravel will lie on the true bedrock. The gravel, which is 20 feet deep, is a loose, clean wash, with a few large bowlders. The gold is coarse and well worn, and nearly 950 fine. The owners state that the value in gold per cubic yard is from 25 cents to $1.50, with a little platinum. Prospecting was done by sinking shafts.
The dredge was designed by the manager, T. R. Heintz. The gravel is raised on the principle of the hydraulic elevator, the water being forced through the suction pipe by a centrifugal pump, and with the gravel is conveyed in a stave pipe to a 5-foot sluice paved with blocks. There are two undercurrents at the end of the sluice. The manager estimates the average cost of dredging at 5 cents per cubic yard. The average horse-power consumed is 750, at a cost of $3,750 per month. However, the amount of gravel handled is placed at 5,000 cubic yards each twenty-four hours. The cost of the plant is $100,000.
102 Gold Drbdoinq In Califobnu.
Trinity County.
The only dredge in operation is at Trinity Center, on gravel bars adjoining the Trinity River ; but considerable areas of gravel have been located on bars along the river with a view to dredging. Of this, nearly 2,000 acres are owned by two companies^ one operating and the other proposing to build a dredge. There are along the river many bars that probably contain sufficient values, but a majority of them are too snLall for the cost of a plant.
Prospecting.— All the prospecting has been done by sinking shafts.
Values.— The values are not evenly distributed, but in the best areas are fair. In most cases 15 cents or more is claimed.
Oravel.— The depth of the gravel varies from about 15 to 25 feet. It is a clean wash, comparatively free from elay. The bowlders are lai^e in places, but there are not enough of them to interfere materially with the work. (See 111. No. 61.)
Bedrock.— The bedrock is slate, usually hard enough to interfere with the saving of coarse gold.
Power.— Steam.
Water. —Abundant.
l1
S3
El
55
104 Gold Dredoinq In Califoknia.
Labor.— Wincianen, $3 to $4; laborers, $2.50 to $3.
Transportation.— Sy team from Redding.
Gold.— The gold is coarse, aa is also the platinum, of which there is considerable. In the dredge at Trinity Center, one-inch holes are used in the screen. There has been dredged about 33 acres.
The problem in Trinity Comity, as in Siskiyou County, is to devise a means of cutting the bedrock or cleaning it. A large proportion ot the coarse gold is on the bedrock, or in it in crevices. Excepting in spots, this can not be dredged by the bucket dredges without a great deal of breaking down of parts.
Companies Operating.
Alta Bird Mining and Dredging Company, Clary, Payne & Kieman, Trinity Center. In Sees. 32 and 33, T. 37 N., R. 7 W., and Sees. 4 and 5, T. 36 N., B. 7 W. Area of holdings, 687 acres. This company began operations April, 1901, and has worked 5 acres. It has one 3% ci- ^■ bucket dredge (Urie, Kansas City, make), and contemplates building another, or putting in a hydraulic elevator.
Trinity Gold Dredging Company, H. G. Comstock, secretary, S(ui Francisco. In T. 33 N., R. 9 W. Area of holdings, 1,100 acres. On this property a dredge worked 30 acres and was dismantled, not being strong enough. A 5 cu. ft. Monarch bucket drec^e is now proposed.
Gold Dredging In California. 105
Siskiyou County.
There are in Siskiyou County three mines being worked" with hydraulic elevators— two successfully in the Oro Fino district and one in Quartz Valley. One Kisdon dredge is working at Callahan, on Scott River. A dipper dredge has been worked at Hawkinsville, but is not now in operation, and one on the Klamath River, which is also idle.
As in nearly all cases in the mountain districts of California, the bedrock is harder than in any of the Sacramento Valley districts, such as Oroville, Yuba, and Folsom. It has so far been found almost impossible to work by dredging, for the hard bedrock prevents the clean . saving of the values, and breaks the bucket and other parts of the ladder.
The values are in many cases very high, but as the gold is usually coarse, much of it lies on the bedrock. So far, hydraulic elevators seem to do the best work wherever there is not too much water to prevent cleaning the bedrock.
The area of gravel in this county now being worked or under consideration by the elevators and dredges amounts to about 2,000 acres, but there is much more that would be exploited if more successful methods of operation could be devised.
Companies Operating.
Wright & Fletcher. H. D. Wright and Mrs. C. D. Frye, Fort Jones. In Sec. 18, T. 43 N., R. 9 W. In the Oro Fino Mining District. Area of holdings, 200 acres. This company began operations in 1890, and has worked 20 acres of ground. The values are not given. In depth the gravel is from 20 to 60 feet, and consists largely of basaltic angular fragments. There are no bowlders. The bedrock is soft schists. Laborers are paid $2.50 per day. The gold is mostly fine and worth $16 per ounce.
This mine is being worked with an Evans hydraulic elevator, with an outlet pipe 20 inches in diameter. The lift is 20 feet. The pressure pipe is 11 inches in diameter, with a head of 14 feet. The flume is 3 feet wide, with block paving.
Eastlick & Gardner. L. Eastlick, of Fort Jones, and S. Gardner, of Greenview. In Sec. 17, T. 43 N., R. 9 W., in the Oro Fino Mining District. Area of holdings, 25 acres. This company began operations in 1890, and has worked 8 acres. The values are not given. In depth the gravel is from 25 to 40 feet, and consists largely of schist and porphyry in fragments which are not much rounded. There are no bowlders. The bedrock is mostly soft slate. Laborers receive $2.50 per day. The gold is mostly fine and worth $16.25 per ounce.
GOLD DBEDGINQ m OAUFORNIA.
This mine is being worked with two Evans elevators. One has a 22-iDch outlet pipe, a lift of 32 feet, and a 15-inch pressure pipe with a head of 300 feet. The other has an outlet pipe 13 inches in diameter, the lift is 32 feet, and the pressure pipe is 13 inches in diameter with a head of 300 feet. The flumes are 24 inches wide, with block pavements and Hungarian rifBes.
Porters Bar Dredging Company, J. R. Wade, general superintendent, Calla^ han. In Sees. 6, 7, and 17, T. 40 N., R. 8 W., below Callahan, on Scott River. Area of holdings, 1,000 acres. The dredge ofthis company has been at work in the Scott River, below Callahan, for a number of years, but was purchased by the present company in the summer of 1904, when it also acquired larger holdings below the present workings. The new company has made an examination of its property with drills, checked by shafts sunk. The values are not given. In depth the gravel averages about 36 feet, and varies considerably in character of material, there being many large bowlders, making an open connection of buckets necessary. The bedrock varies, some being shale, but mostly hard greenstone.
Gold Dred0In6 In Calipoenia. 107
Electric power generated by water power beloQging to the company is used- The amount eonaumed in the dredge is 100 horse-power, which costs $2 per horse-power per month. There is an abundance of cheap water in all this country. Wages are $3 for winchmen, and $2.25 and $2.50 for ordinary laborers. Transportation is by rail from San Francisco, 337 miles, and by team over reasonably good roads, 25 miles from Gazelle. Scott Valley furnishes food supplies at low rates. The gold is coarse and worth from $17 to $18 per ounce. No platinum is found.
The company proposes to have the dredge dig its own channel down the river over a mile to where the bedrock is softer. The dredge is of the Risdon type, with 5 cu. ft. bucket capacity, and the owners are at present making some modifications, particularly as to the bucket line, on account of the hardness of bedrock. The buckets are to be made much stronger, with lips heavier than is usual. These are 8 inches wide, and weigh about 140 pounds, against the usual 90 pounds, and protrude about 2 inches beyond the bucket. The links on which the buckets are placed are 6^4 inches deep and are connected by 2%-inch pins. These links are 26 inches between center pins. The sides of the tumbler are 21i/^ inches.
108 Gold Dredging In Caufoenia.
Yreka Creek Gold Dredging Company, George A. Lounsberry, Ocean Park, Los Angeles County. In T. 45 N., R. 7 W. Area of holdings, 200 acres. Operations were commenced in 1899, with a single dipper dredge ; but outside of the dipper, the installation to handle the gravel consists of two identical plants, one on each side of the dredge. Spuds are used for holding the boat in place. The dipper, of 1 cubic yard capacity, dumps on a revolving screen 18 feet long, with 1-incK holes in the first 10 feet and %-inch holes in the remaining 8 feet.. The sluicing tables are provided with burlap and wire-mesh riflSes, together with sluice-boxes, 30 inches wide, with Hungarian riffles. A bucket stacker is used. It is claimed that under favorable conditions the dredge can handle 1,400 cubic yards daily. Owing to hard bedrock, there were continual breakdowns and the dredge is now idle. (See 111. No. 63.)
Klamath River Gold Mining Company, J. A. Foster, president. Biggs. In Sec. 22, T. 46 N., R. 7 W., on the Klamath River. Area of holdings, 77 acres. This company began operations in June, 1904, with a dredge designed by Mr. French. It is a steam-shovel dredge, but the bucket does not work on a boom, it being moved by two steel cables. This company's property is on Garvey's Bar, on the Klamath River, a little above the mouth of Humbug Creek. The average depth of the gravel is 60 feet, lying on a medium hard slate. It is coarse and there are many large bowlders. It is a blue gravel, with sulphurets, but without black sand. The gold is mostly fine, and worth about $17.80 per ounce. Wages are $4 for the engineer, and $2 for laborers. Steam power costs $5 per horse-power per month. At present the dredge is not being operated.
A, C, Brokaw, Fort Jones, is operating an hydraulic elevator in Quartz Valley. It is of the Hendy type, of 20 inches diameter, with 6-inch nozzle. With 1,500 inches of water under 230 feet of pressure, the owner reports that 2,500 cubic yards of gravel is raised 30 feet in twenty-four hours.
Appendix.
■' Un
California State Mining Bureau.
This institution aims to be the chief source of reliable information about the mineral resources and mining industries of California.
It is encouraged in its work by the fact that its publications have ! been in such demand that large editions are soon exhausted. In fact,
copies of them now command high prices in the market.
The publications, as soon as issued, find their way to the scientific, public, and private libraries of all countries.
State Mineralogist.
I
The California State Mining Bureau is under the supervision of Hon. Lewis E. Aubury, State Mineralogist. \^ It is supported by legislative appropriations, and in some degree
performs work similar to that of the geological surveys of other States; but its purposes and functions are mainly practical, the scientific work being clearly subordinate to the economic phases of the mineral field, as shown by the organic law governing the Bureau, which is as follows :
Sec. 4. It shall be the duty of said State Mineralogist to make, facilitate, and i encourage special studies of the mineral resources and mineral industries of the
State. It shall be his duty : To collect statistics concerning the occurrence of the I economically important minerals and the methods pursued in making their valuable
constituents available for commercial use ; to make a collection of typical geological and mineralogical specimens, especially those of economic or commercial importance, such collection constituting the Museum of the State Mining Bureau; to provide a library of books, reports, drawings, bearing upon the mineral industries, the sciences of mineralogy and geology and the arts of mining and metallurgy, such library constituting the Library of the State Mining Bureau; to make a collection of models, drawings, and descriptions of the mechanical appliances used in mining and metallurgical processes ; to preserve and so maintain such collections and library as to make them available for reference and examination, and open to public inspection at reasonable hours; to maintain, in effect, a bureau of information concerning the mineral industries of this State, to consist of such collections and library, and to arrange, classify, catalogue, and index the data therein contained, in a manner to make the information available to those desiring it, and to provide a custodian specially qualified to promote this purpose; to make a biennial report to the Board of Trustees of the Mining Bureau, setting forth the important results of his work, and to issue from time to time such bulletins as he may deem advisable concerning the statistics and technology of the mineral industries of this State.
The Bulletins.
The field covered by the books issued under this title is shown in the list of publications. Each bulletin deals with only one phase of mining. Many of them are elaborately illustrated with engravings and maps. Only a nominal price is asked, in order that those who need them most may obtain a copy.
112 California State Mining Bureau.
The Registers Of Mines.
The Eegisters of Mines form practically both a State and a County directory of the mines of California, each county being represented in a separate pamphlet. Those who wish to learn the essential facts about any particular mine are referred to them. The facts and figures are given in tabular form, and are accompanied by a top(^graphical map of the county on a large scale, showing location of each mineral deposit, towns, railroads, roads, power lines, ditches, etc.
Home Of The Bureau.
The Mining Bureau occupies the north half of the third floor of the Ferry Building, in San Francisco. All visitors and residents are invited to inspect the Museum, Library, and other rooms of the Bureau and gain a personal knowledge of its operations.
The Museum.
The Museum now contains over 16,000 specimens, carefully labeled and attractively arranged in showcases in a great, well-lighted hall, where they can be easily studied. The collection of ores from California mines is of course very extensive, and is supplemented by many cases of characteristic ores from the principal mining districts of the world. The educational value of the exhibit is constantly increased by substituting the best specimens obtainable for those of less value.
These mineral collections are not only interesting, beautiful, and in every way attractive to the sightseers of all classes, but are also educational. They show to manufacturers, miners, capitalists, and others the character and quality of the economic minerals of the State, and where they are found. Plans have been formulated to extend th« usefulness of the exhibit by special collections, such as one showing the chemical composition of minerals; another showing the mineralogical composition of the sedimentary, metamorphic, and igneous rocks of the State; the petroleum-bearing formations, ore bodies, and their country rocks, etc.
Besides the mineral specimens, there are many models, maps, photographs, and diagrams illustrating the modern practice of mining, milling, and concentrating, and the technology of the mineral industries. An educational series of specimens for high schools has been inaugurated, and new plans are being formulated that will make the Museum even more useful in the future than in the past. Its popularity is shown by the fact that over 100,000 visitors registered last year, while many failed to leave any record of their visit.
114 California State Mining Bureau.
The Library.
This is the mining reference library of the State, constantly consulted by mining men, and contains between 4000 and 5000 volumes of selected works, in addition to the numerous publications of the Bureau itself. On its shelves will be found reports on geology, mineralogy, mining, etc., published by states, governments, and individuals; the reports of scientific societies at home and .abroad; encyclopaedias, scientific papers^ and magazines; mining publications; and the current literature of mining ever needed in a reference library.
Manufacturers' catalogues of mining and milling machinery by California firms are kept on file. The Registers of Mines form an up-to-date directory for investor and manufacturer.
The librarian's desk is the general bureau of information, where visitors from all parts of the world are ever seeking information about all parts of California.
Reading-Room.
This is a part of the ^Library Department and is supplied with over one hundred current publications. Visitors will find here various California papers and leading mining journals from all over the world.
The Library 'and Eeading-Room are open to the public from 9 a. m. to 5 F. M. daily, except Sundays and holidays.
The Laboratory.
This department identifies for the prospector the minerals he finds, and tells him the nature of the wall rocks or dikes he may encounter in his workings; but this department does not do assaying nor compete with private assayers. The presence of minerals is determined, but not the percentage present. No charges for this service are made to any resident of the State. Many of the inquiries made of this department have brought capital to the development of new districts. Many technical questions have beeaa asked and answered as to the best chemical and mechanical processes of handling ores and raw material. The laboratory is well equipped.
The Draughting-Room.
In this room are prepared scores of maps, from the small ones filling only a part of a page, to the largest County and State maps; and the numerous illustrations, other than photographs, that are constantly being required for the Bulletins and Registers of Mines. In this room, also, will be found a very complete collection of map» of all kinds relating to the industries of the State, and one of the important duties of the department is to make such additions and corrections as will keep the maps up to date. The seeker after information inquires here if he wishes to know about the geology or topography of any district ; about the locations of the new camps, or positions of old or abandoned
California State Mining Bureau.
ones; about railroadSj stage roads, and trails; or about the working drawings of anything connected with mining.
Mineral Statistics.
One of the features of this institution is its mineral statistics. Their annual compilation by the State Mining Bureau began in 1893. No other State in the Union attempts so elaborate a record, expends so much labor and money on its compilation, or secures so accurate a one.
The State Mining Bureau keeps a careful, up-to-date, and reliable but confidential register of every producing mine, mine-owner, and mineral industry in the State. From them are secured, under pledge of secrecy, reports of output, etc., and all other available sources of information are used in checking, verifying, and supplementing the information so gained. This information is published in an annual tabulated, statistical, single-sheet bulletin, showing the mineral production by both substances and counties.
Total Gold Product Of California— 1848-1903.
18a3 $23,501,736
I860 17,930,858
Total.. $1,395,746,672
County Rank In Gold Product In 1903.
While gold is still the leading mining product, its yield no longer puts the greatest gold-producing county in the first place. The petroleum of Kern County and the copper of Shasta give them precedence. Gold is more widely distributed than any other substance thus far mined in California; 34 counties out of the 57 in the State showing a gold yield in 1903, and it is known to exist in several others. The order in rank of the counties of the State, in the production of gold alone, is at present as follows :
Fresno $21,538
Riverside 13,453
Tulare 9,215
Monterey 8,920
Los Angeles _.. 8,674
Del Norte 7,183
Alpine 2,701
San Luis Obispo 1,840
Ventura . 1,087
Orange 150
Total $16,471,264
118 California State Mining Bureau.
Total Mineral Product Of California For 1903.
The following table shows the yield and value of mineral substances
of California for 1903, as per returns received at the State Mining Bureau, San Francisco, in answer to inquiries sent to producers :
Quantity. Value.
Asphalt 41,670tons $503,659
Bituminous Rock 21,944 " 53,106
Cement. 640,868 bbls. 968,727
Chrome. 150 tons 2,250
Clays: For Pottery :. 90,972 tons 99,907
For Brick- . 214,403 M 1,999,546
Coal _ 93,026ton8 265,383
Copper -..- 19,113,861 lbs. .2,520,997
Fuller's Earth 250 tons 4,75Q
Gold - 16,471,264
Granite 408,625 cu. ft. 678,670
Gypsum 6,914 tons 46,441
Infusorial Earth 2,703 " 16,015
Lead. 110,000 lbs. 3,960
Lime. .- 496,587 bbls. 418,280
Limestone 125,919 tons 163,988
Macadam 605,185 " 436,172
Manganese _.- 1 " 25
Magnesite 1,361 ** 20,515
Marble. 84,624cu.ft. 97,354
Mica .... 50tons 3,800
Mineral Paint 2,370 " 3,720
Mineral Water .... 1,978,340 gals. 558,201
Natural Gas 120,134 Mcu. ft. 75,237
Paving Blocks. 4,854 M 134,642
Petroleum 24,340,839 bbls. 7,313,271
Platinum. 1,052
Pyrites 24,311 tons 94,000
Quartz Crystals _ 1,968
Quicksilver 32,094 flasks 1,335,954
Rubble :. 1,610,440 tons 1,237,419
Salt 102,895 '♦ ' 211,365
Sandstone 353,002 cu. ft. 585,309
Serpentine- -- 99 " " 80O
Silver 517,444
Slate 10,000 squares 70,000
Soapstone __ 219 tons 10,124
Soda 18,000 " 27,000
Tourmaline.. _ 100,000
Turquoise 10,000
Total value ., $37,759,040
California State Mining Bureau.
Relative Rank Of Counties In Total Mineral Product In 1908.
34. S'nLuisObijpo 257,416
Unapportioned 377,783
Total $37,759,040
Mining Bureau Publications.
Publications of this Bureau will be tent on receipt of the requisite amount and postage. Only stamps, coin or money orders will be accepted in payment. (All publications not mentioned are exhausted.)
Attention is respectfully called to th?t portion of Section 8, amendment to the Mining Bureau Act, approvd March 10, 1903, which states :
'*The Board (Board of Trustees) is breby empowered to fix a price upon, and to dispose of to the public, at such price, any and all publications of the Bureau, including reports, bulletins, maps, registers, etc. The sum derived from such disposiion must be accounted for and used as a revolving printing and publihing fund for other reports, bulletins, maps, registers, etc. The pices fixed must approximate the actual cost of printing and issuing tie respective reports, bulletins, maps, registers, etc., without reference to the cost of obtaining and preparing the information embraced theein.'*
Price. Postage.
ReportXI— 1892, First Biennial... $100 $0 15
Report Xni~1896, Third Biennial _ 100 20
Bulletin No. 5— "Cyanide Process" (4th edition )pound_ _. 60 08
Bulletin No. 6— "Gold Mill Practices in Californis' (3d edition) 50 04
Bulletin No. 9— "Mine Drainage, Pumps, etc.," bund 60 08
Bulletin No. 15-^"Map of Oil City Oil Fields, Freao County, Cal." 05 02
Bulletin No. 16 — "Genesis of Petroleum and Aspbltum in California,"
Bulletin No. 18— "Mother Lode Region in Califorra" 35 oe
Bulletin No. 23— "Copper Resources of California'. 50 12
Bulletin No. 24— "Saline Deposits of California" 50 10
Bulletin No. 27— "Quicksilver Resources of Califo»ia" 75 og
Bulletin No. 30— "Bibliography Relating to the Oology, Palaeontology
and Mineral Resources of California, includingList of Maps" 50 10
Bulletin No. 31 — "Chemical Analyses of Californi Petroleum" __ 02
Bulletin No. 32— "Production and Use of Californi Petroleum" 75 08
Bulletin No. 33— "Mineral Production of Californi— 1903" 02
120 California State Mining Bureau.
Price. Postage.
Bulletin No. 34— "Mineral Production of California for 17 Years" $0 02
Bulletin No. 35 — "Mines and Minerals of California" 04
Map of Mother Lode $0 05 02
Gold Production in California from 1848 to 1904 02
Register of Mines, with Map, Plumas County 25 08^
Register of Mines, with Map, Siskiyou County 25 08-
Register of Mines, with Map, Trinity County 25 08^
Register of Mines, with Map, Lake County 25 08-
Register of Mines, with Map, Nevada County 25 08
Register of Mines, w4th Map, Placer County 25 08^
Register of Mines, with Map, El Dorado County — 25 08-
Register of Mines, with Map, Inyo County 25 08
Register of Mines, with Map, Shasta County 25 08
Register of Mines, with Map, San Bernardino County 25 08-
Register of Mines, with Map, San Diego County 25 08
Register of Mines, with Map, Sierra County 25 08
Register of Mines, with Map, Amador County- 25 08
Register of Mines, with Map, TuolumneCounty 25 08
Register of Mines, with Map, Butte Couity 25 08
Register of Mines, with Map, Mariposa County 26 08
Register of Mines, with Map, Kern Coiiiity 25 08
Register of Oil Wells, with Map, Los ingeles City 35 02
Relief and Mineral Map of California - 25 05-
In Preparation :
Gems and Jewelers' Materials of Califcrnia
Structural and Industrial Materials of California
Samples of any mineral found in the State may be sent to the Bureau for identification, and Hie same will be classified free of charge.
It must be understood, however, that no assays, or quantitative determinations, will he made. Samples should be in lump form if possible, and the outside of package skould be marked plainly with name of
sender, postoffice address, etc., find a stamp should be inclosed for reply.
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