Some thorium prospects, Lemhi Pass area, Beaverhead County, Montana
The Last Chance group> Brown Bear and Shady Tree claims in Beaverhead County, Mont., were explored for thorium under a Defense Minerals Exploration…
Public-domain full text preserved in the Mountain Man Mining Library. Original source: pubs.usgs.gov.
L E M H I PASS AREA BEAV'ERHEAD COUNTY, MONTANA By Frank C. Armstrong Trace Elements Memorandum Report UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY
OFFICIAL USE ONLY Geology and Mineralogy This document consists of fgp pages, plus 1 figure. Series A UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY SOME THORIUM PROSPECTS LEMHI PASS AREA? BEAVERHEAD COUNTY, MONTANA* By Frank C. Armstrong June 1955 Trace Elements Memorandum Report This preliminary report is distributed without editorial and technical review for conformity with official standards and nomenclature. It is not for public inspection or quotation. report concerns work done on behalf of the Defense Minerals Exploration Administration and the Division of Materials of the U 0 S, Atomic Energy Commission. OFFICIAL USE ONLY
OFFICIAL USE OHLY USGS - TEM-918 GEOLOGY AMD MINERALOGY Distribution (Series A) No, of copies Atomic Energy Commission, Washington Division of Raw Materials, Albuquerque „
„ . Division of Raw Materials, Butte 6 Division of Raw Materials, Casper .
„
, „ „
Division of Raw Materials, Denver,, 0 0 o Division of Raw Materials, Hot Springs „ „
Division of Raw Materials, Ishpeniing „ „ „ „
Division of Raw Materials, Phoenix Division of Raw Materials , St 0 George 0 0 Division of Raw Materials, Salt Lake City 0 Division of Raw Materials, Washington. . „ 0 . Exploration Division., Grand Junction Operations Office „ Grand Junction Operations Office .. 600 0()0
Technical Information Service, Oak Ridge U. S 0 Geological Surveys Fuels Branch, Washington Geochemistry and Petrology Branch, Washington. Geophysics Branch,, Washington. . , , „ "„ „
Mineral Deposits Branch, Washington. .
„
E 0 H 0 Bailey, Menlo Park Ao Lo Brokaw, Grand Junction 0 .o. No M. Denson, Denver Mo Ro Klepper, Spokane . „
o r . H 0 Koschmann, Denver Lo R. Page, Washington . ... b Qo D, Singewald, Beltsville. .
„
o A,, j£ 6 Weissenborn, Spokane 0 „
TEFCO, Denver o TEPGO, RPS 5 Washington, (including master) _jOFFICIAL USE ONLY
OFFICIAL USE 'CONTENTS Page Abstract
„ 4 Introduction 5 Geology. „ Regional geology. 8 Geology" of the Last Chance and Shady Tree claims. Geology of the Brown Bear claim 12 Results of diamond drilling. 13 Samples. 15 Literature cited 21 Appendix A . . . . ILLUSTRATIONS Figure 1. Index map showing location of last Chance group of claims 3 Beaverhead County, Montana 2. Last Chance group of claims, Beaverhead County, Montana 7 3. Geologic map and sections of the Last Chance vein, Beaverhead County, Montana. ... In envelope TABLES Table 1. Surface sample data, Last Chance and Brown Bear claims Beaverhead County, Montana 16 Assays of diamond drill holes nos. 1 and Last Chance claim, Beaverhead County, Montana 18 Semiquantitative spectrographic analyses of samples from diamond drill holes nos. 1 and 2, Last Chance claims, Beaverhead County, Montana. 19 OFFICIAL USE ONLY.
OFFICIAL USE OKU SOME THORIUM PROSPECTS, LEMHI PASS AREA,, EEAVERHBAD COUNTY, MONTANA By Frank C e Armstrong ABSTRACT The Last Chance group.9 Brown Bear 5 and Shady Tree claims in BeaTerhead County, Mont. were explored for thorium under a Defense Minerals Exploration Administration Contract in 1951 and 1952 The project was undertaken to explore northwest-trending, moderately to steeply dipping thorite-bearing quartz-barite-hematite veins. The veins are wall-rock replacements and fissure fillings in faults and shears that cut rocks of the Precambrian Belt series. Recurrent movement along the faults has intensely fractured the veins„ Quartz, iron-oxide minerals,, and thorite have been deposited in these fractures. The iron oxides and thorite are intimately associated and were among the last minerals deposited,. Because no rare earth or uranium minerals have been found in the veins, it is thought that the small amounts of these elements reported in the analyses must substitute for thorium in the thorite. Under the D. M. E 0 A 0 contract the Last Chance vein was traced on surface for a distance of about 1,300 feet; the thickness ranges from about 35 feet to a few inches. Two diamond drill holes cut the vein 240 and 290 feet below the outcrop. OFFICIAL 0SS QtfLI
OFFICIAL USE omr IHTRODUCTIOH The Last Chance group. Brown Bear and Shady Tree claims are in the Nj sec. 28, sec. 29 and Sj sec. 2Q5 T. 10 S e ,, R. 15 W OJ) in the unorganized Frying Pan mining district of western Beaverhead County
Mont which is just east of the McDevitt mining district in Lemhi County, Idaho >(fig. l). The property consists of seven contiguous,, unpatented lode claims and one tunnel site claim (fig* 2). The property is about 2 3/4 miles south of a point on the Lemhi Pass road that is about 10 miles east of Tendoy, Idaho, and 30 miles west of Armstead, Mont, The road between Tendoy and Amstead is a graded dirt road and is open to ordinary vehicles about 6 or 7 months of the year. Access to the property from the Lemhi Pass road'is over a poorly defined sheep camp trail that runs south from where the Lemhi Pass road crosses the Continental Divide 'on the Idaho-Montana state line. Both the Union Pacific Railroad and U 6 S. Highway 91 pass through Armstead. The nearest source of mining supplies is 51 miles distant at Dillon, the county seat of Beaverhead County. The Geological Survey first examined the Lemhi Pass area for thorium in 1950 (Trites and Tooker, 1953); and in 1952 Sharp and Calender (written communication) made a more detailed geologic study of the area. In the spring of 1951, the filkhorn Mining Co., Boulder 9 Mont., applied for a Defense Minerals Exploration Administration contract to explore the Last Chance group Brown Bear 5 and Shady Tree claims for thorium. Assays taken from veins on the property justified a limited exploration program for thorium, consequently DMSA Contrast OFFICIAL USB OHLT
DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY TRACE ELEMENTS MEMORANDUM REPORT 918 Last Chance group of claims To Tendoy, Idaho 10 miles Last Chance group of cla FIGURE I.-INDEX MAP SHOWING LOCATION OF LAST CHANCE GROUP OF CLAIMS BEAVERHEAD COUNTY, MONTANA 8 MILES
DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY TRACE ELEMENTS MEMORANDUM REPORT 918 LAST CHANCE NO. 2 LAST CHANCE NO. 3 LAST CHANCE NO. 4 Modified from a map furnished by the Elkhorn Mining Company FIGURE 2. - LAST CHANCE GROUP OF CLAIMS BEAVERHEAD COUNTY, MONTANA D M E A Docket No. 1186 I20C FEET
OFFICIAL USE ONLY a DMEA Docket No. 1186, was granted the applicant September li., 1951. Under the contract ?00 feet of bulldozer trenching was done ? most of it on the Last Chance claim where trenching exposed the main vein in several places. Small bulldozer cuts on the Shady Tree and Brown Bear claims exposed a few narrow veins 0 In addition,, the main vein on the Last Chance claim was cut by 2 diamond drill holes (fig. 3) contract was terminated by mutual agreement in June 1953$ without com- pleting the drilling allowed in the contract. This report relates to the results obtained by the exploration work done primarily under the Defense Minerals Exploration Administration contralto It was also prepared partly on behalf of the Division of Raw Materials of the U 0 S 0 Atomic Energy Commission, GEOLOGY Regional geology The Beaverhead Mountains in the vicinity of Lemhi Pass are underlain by light- to dark-gray 5 micaceous quart zite<> dark-gray argillite, and argillaceous quartzite of the late PreCambrian Belt series. These rocks are intricately folded,, but because of poor exposures, the pattern of the folds has not been worked out. The veins in the area occur in faults that trend northwest 0 The veins are wall-rock replacements and fissure fillings along faults and shears and are composed dominantly of quartz with some barite iron oxides and hydroxides, an lesser amounts of thorite. OFFICIAL USE QNLI
OFFICIAL USE OSLY Geology of the Last Chance and Shady Tree claims Figure 3 is a geologic map of a part of the Last Chance and Shady Modified after unpublished map by W. N. Sharp and W. S 0 Calender, Tree claims. The area is underlain by gently dipping quartzite, argillaceous quartzite, and quartzitic sandstone of the Belt series. Because of poor outcrops the different rock types were not mapped separately. The southern part of the Last Chance vein strikes about N, 45° W., and the north end strikes about N. 60° W. (fig. 3) The results of the diamond drilling indicate that the south third of the vein dips about 45° S¥. a dip of 64° NE. was observed on surface near the north end of the vein. The vein crops out for a distance of 500 feet and has been traced on the surface for a total distance of about 1300 feet| it extends at least 290 feet down the dip (Sec. A-A f ). Over the southern two-thirds of its length the thickness of the vein is between 10 and 15 feet| near the south end the vein has a maximum thickness of about 35 feet. The northern third of the vein progressively narrows and finally the vein dies out entirely. Several smaller veins 5 parallel or subparallel to the major vein, occur in the wall rocks. The largest of these, located about 35 feet northeast of the foot wall of the Last Chance vein, is 4 feet thick and is about midway between the ends of the major vein. OFFICIAL US£ ONLY
OFFICIAL USE ONLY ID The Last Chance vein occupies a fault and has been emplaced by replacement of the brecciated wall rock and to a lesser extent by fissure filling. Even though replacementhas played a large part in its formation the contact of the vein with the wall rocks is sharp. The wall rocks have been intensely bleached for a distance of 3 to 5 feet N, from the vein and locally they appear to be highly silicified. Numerous silicified breccia fragments of wall rock occur in and near the margins of the vein. The vein is intensely fractured from recurrent movement along the fault after the emplacement of the vein. Fracturing of the vein is most intense at points where abrupt changes in its strike occur. The vein consists of milky quartz and subordinate barite$ barite is only locally abundant and in most places is much less abundant than quart z,. The wide part of the vein about 550 feet from its north end (fig.3)> however, is dominantly barite with only sparse quartz. Barite in white ? finely crystalline masses and in pink Teinlets replaces some of the quartz. The quartz and barite have been intensely fractured and later quartz and barite 5 and goethite, lepidoerocite, specular and earthy hematite have been deposited in the fractures as Teinlets from less than an inch to several inches thick. In the barite- rich part of the vein a banding parallel to the vein walls results from alternate layers of barite and dark-red, hematite-impregnated layers of barite. A little malachite was also rioted in the vein. The presence of iron oxides and hydroxides in the numerous fractures colors almost the entire vein red. OFFICIAL USE OHU
OFFICIAL USE OHLY n The only mineral of economic importance in the vein, thorite .SiC), was identified by the Geological Survey Laboratory at Washington; D. C, by X-ray diffraction patterns. The thorite and its alteration products are dark red-brown,, and the presence of abundant similarly colored iron compounds in the vein makes the megascopic identification of thorite difficult. The thorite occurs as irregular to rounded masses, and as irregular streaks and blebs smeared along fracture surfaces according to Sharp and Cavender (written communication), but Sharp and Cavender (written communication) and Trites and Tooker (1953) also report that thorite crystals occur throughout the vein and disseminated in quartz. Trites and Tooker (1953) also observed that the thorite crystals appear to be associated with red hematite c The author visited the property on September 3, 1953 but did not observe the disseminated thorite crystals reported by the previous workers 0 Most, if not all, of the thorite seems to occur along fractures in the quartz or barite, and possibly is genetically associated with specular hematite-earthy hematite mineralization. Microscopic examination of two thin sections of material cut in Diamond Drill Hole no. 2 shows the vein material to be severely crushed and finely ground, so that in places the vein has the texture of mylonite. Strain shadows in the quartz are abundant Several generations of quartz filling the fractures are evident, and locally the quartz is recrystallized. Almost without exception any mineral that might be thorite is in a healed fracture, and the great majority of material that looks like thorite is in prominent iron oxide-filled fractures. The iron oxides appear to have been among the last minerals to have been deposited in the vein, OFFICIAL USE ONLY
The well-fractured parts of the vein should,, therefore generally be richest in thorite and iron-oxide veinlets. Rare earths have been reported in.analyses of samples from the vein,, but no rare-earth minerals have been identified. The amount of rare earths reported in the analyses is such that all of it can be accounted for as substituting for thorium in the mineral thorite,, and5 therefore, rare-earth minerals need not be present. Analyses show that there is very little uranium in the vein. What uranium is present could also be accommodated by substitution for thorium in the thorite. Geology of the Brown Bear claim In the northwest corner of the Brown Bear claim one cut exposed a vein that is traceable for about 250 feet. Hear its south end the vein is ij feet thick, and at its north end,, beyond the north boundary of the Brown Bear claim, it is 3 feet thick,, Its strike and dip change from N 0 50° W., 49° SW. at the south end, to N, 15°~20° W., 54° SW. at the north end. A smaller parallel vein is also exposed in the bulldozer cut. In the northeast corner of the Brown Bear claim four veins are exposed in one cut. The two larger veins, each paralleled for a short distance by a smaller vein, have been traced 200 to 250 feet to the southeast. One pair of veins strikes N. 65° W. and dips 3? SW.5 the other pair strikes N. 25°-30° W., and dips 25° SW. Both of the larger veins are 6 to 8 inches thick.
OFFICIAL USB ONU All of the veins on the Brown Bear claim are like those on the Last Chance and Shady Tree claims. They are thorite-bearing quart z~barite- specular hematite-earthy hematite veins in which the thorite is associated with the iron oxides* RESULTS OF DIAMOND DRILLING Three diamond drill holes were drilled on the Last Chance claim5 but only two of them cut the Last Chance vein. Detailed geologic logs of the holes showing recovery, size of hole,, and description of material are given in Appendix A. Hole no. 1 was drilled 239 feet bearing N. 43° E 0 and inclined 45 degrees from the horizontal (fig. 3)* The drill hole cut vein material at 2235 feet. The hanging wall rocks showed strong bleaching for several feet above the vein. From 223.5 to 231.0 feet the core consists of brecciated, iron-stained quartz veined by specular hematite and other reddish iron compounds. About 60 percent of the core was recovered from that 7.5-foot infcervalj no sludge was saved. From 231 to 239 feet only 2 inches of core consisting of vein material similar to that from 223o5 to 231 feet was recovered. The drillers reported good water return going through 'the vein zone, and a sandy sludge was recovered from the interval 231 to 239 feet. When this sludge was examined with a (Jeiger counter, the needle went off its most sensitive scale. Inasmuch as the sludge was the most radioactive material recovered.it appears that hole no. 1 may not have penetrated the entire vein zone. Personnel of the U. S. Atomic Energy Commission tried to log this hole radionietrieally but could not do so because it had caved* OFFICIAL USE ONLY
Official Use Obly
Diamond drill hole no e 2 was drilled 303 feet bearing N. 40° E. and inclined 45 degrees from the horizontal (fig 0 3). The hanging wall of the vein cut by hole no. 2 is silicified and strongly bleached. The hole cut vein material at 264.6 feet 5 and there was vein material and silicified wall rock in the core from that point to the bottom of the hole. Although the hole bottomed in mineralized material it is thought that the foot wall of the main vein zone is at '284 6 feet. The most radioactive part of the core 3 as shown by examination with a Geiger counter is from 264.6 to 269 feet. The core below 269 'feet is not very radioactive.
Personnel of the Atomic Energy Commission 8 s Butte suboffice made a radiometric log (see Appendix A) of the hole. This log shows the most radioactive part of the hole to be at about 280 feet and the second most radioactive part to be about 266 feet. Radioactivity was not detected in the core at 280 feet, probably because in the interval 277.6 to 284 6 feet core recovery was only 24 percent, whereas from 264.6 to 269 feet it was 100 percent. The radiometric log shows the start of another radiometric high at the bottom of the hole and it is possible that the hole has not cut the full thickness of the vein zone. Diamond drill hole no. 3 was drilled 95 feet bearing N. 50° E. and Inclined 45 degrees from the horizontal (fig* 3) drilling was esessed for the winter before the hole cut the vein; because the project was terminated the following June 5 the hole was not completed-. OFFICIAL USE ONLY
OFFICIAL gSE ONLY SAMPLES During the course of an investigation of the thorium deposits in' the Leinhi Pass area by the Geological Survey sixteen surface samples were taken from the Last Chance claim and two from the Brown Bear claim* The analyses of the samples are listed in table 1 and the sample locations are plotted on figure Diamond drill core samples were assayed by both the Lindsay Chemical Company and by the Geological Survey, A comparison of these analyses is given in table 2, Semiquantitative spectrographic analyses of the samples were also made by the Geological Survey and are listed in table If uranium and thorium are present in a sample in quantities less than 0.1 percent, they are not ordinarily detected spectr©graphically. This fact accounts for the absence of uranium in table 3 and the absence of thorium in some of the samples of table OFFICIAL USE QHLY
Table 1. —Surface sample data # Last Chance and Brown Bear claims, Beaverhead County ? Montana (from Sharp and Cavender. written communication) Sample eU Number ( per cent ) Last Chance vein LC-B LC-E LC-G LC-H .01? KM-LC-1 ,059
/ '/ / // / 19OTT-S24-50 0 1Q/ /. Calculated / ! Th02 f U Th02 Ra (percent) (percent) (percent (gr/gr) ( ObOOl cOOl o06 93 le?0 05 3xlO~12 7xlO~12 .,003
ixio"11; 2.0X10"11
2.5xlO"n o5* Location Remarks Pit on satellite vein Chip sample across M of road, cut ' 3- to 4-ft vein Prominent te"iilargeJfi6nt Chip -sample across of vein N¥ of road cut 20~ft 0 vein outcrop First trench NW of "E" Chip sample across location 3- to 4-fte vein Second trench NW of riE" Chip sample across 3-oeation 4=-ft 0 vein Chip samples 3 ft east to west - Road cut across vein across 10- ft* vein 4 ft Outcrop,, 30 ft. SE of Channel sample road cut &=ft. outcrop Small pit on prominent Grab sample from out crop 5 210 ft. SE of pit road cut Small pit on prominent Grab sample from out crop 210 ft. SE of eherty lens road cut
/, Official Use Only Cd
Table 1 0 —Surface sample data. Last- Chance and Brown Bear claims, Beaverhead County, Montana—Continued /
J (from Sharp and Cavender,, written communication) / Sample Number RE- 0 j O O eU U
(percent) (percent) (percent) (percent) Ra Location Remarks AFT-S25-5Q -=326 Q,43 >44 ,15 ,041 0,005 2.4* ,004 2.4* Small pit on prominent outcrops 210 ft. SE of road cut Outcrop of vein 60 ft* SE of road cut Road cut across vein Road cut across vein Chip sample across 1-ft. of vein Chip sample across 1 ft 0 of vein Chip sample across 5 ft 0 of footwall side of vein Chip sample across 5 fto hanging wall =334 ,001 ,04*- Prominent enlargement of vein NW of road cut Chip sample across 25 fto of vein S-35 Brown Bear claim ,014 ,001 SE end of vein outChip sample across 40 ftc of vein 'AFT-S30-30 Calculated 7.0* Outcrop of vein 150 ft c Chip sample across' m of m trench 3 fto of vein HE trench OFFICIAL USE ONLY Selected composite sample of 6~ino Tein
OFFICIAL USE ONLY Table 2.—Assays of diamond drill holes NO O 1 and 2 9 Last Chance claim, Beaverhead County, Montana Diamond Drill Hole No, 1 / Footage 224.0-226.4 226.4-227.1 227.1-229.2 229. 2-231 o 2 231.2-239.0 J/ V ' 264.6-266.2 266.2-267.5 267.5-269.0 269 ..0-271. 2 271.2-273.0 273.0-274.6 274.6-275.3 ' 275.3-277.0 277.0-277.6 277.6-284.6 U 0 S, """ Equivalent U Percent ,009 8 04$ Weighted ,004 ,007 ' „ Geological Equivalent Th02 Percent average ,072 ,011 ,015 Survey Analyses i/ Lindsay Chemical Company Analyses U3°8 Percent
Diamond cOOl £ .001 Th02 Percent Drill.- Hole No, 2 ,.10 RE2°3 -f THO? Th02 Percent Percent 0,5 0,3
N.D, & NoD0 N 6 D C Oo3 N.D, N.D 0 N.D. N 0D. N.D, N 0Do N 0D 0 0,2, N eD 0 Weighted average I/ Total EEOo was not run because'"the spectrographic report (table 3) showed that they were not sigxiitieantly high. Analysts Audrey Smith and Harry Levine, U. S 6 Geological Survey Washington Laboratory 2/ Not detected 0 3/ Sludge sampleo . OFFICIAL USE ONLY
OFFICIAL USE OMLT Table 3—Semi quantitative spectrographic analyses of samples from diamond drill holes Nos. 1 and 2 ; Last Chance claim, Beaverhead County s Montana„ Diamond Drill Hole No* 1 Over Footage 10$ 224.0-226.4 Si 226.4-227.1 Si 22? o 1-229. 2 Si 229.2-231.2 Si 231.2-239.0 Si .1-105* Fe Al Fe K Al Fe K Fe Al Fe K 0.1-1.0£ Al Ba Mg Th Ba Mg ' Ba Mg Al Ba Ca Na Ba Mg Ti Th Diamond Drill 264*6-266.2 Si 256 e 2-267. 5 Si 26? 0 5-269.0 Si 269,, 0-271. 2 Si Fe Fe Fe Al Al K Fe Ba Al K Th Ca Th Al Ba Ba K Ca Th Mg Na Mg Ca 0.01-0,1$ Ce Pb Ti Mn Gd Cu Nd Sm Eu Sr Th Na Ti Mn Cu Pb Ni Sr 'Na Th Ti Mn Cu Pb Sr Ni Zn Mn Cu Pb Mg Th Ti Ni Sr Ce Nd Gd Y Cu Sr Mn Eu Sm Ni Pb Hole No. 2 Sm Co Pb Mn Ce Ti Sr Gd Cu Mg Ni Nd Mg As Cu Ti Pb Sr Gd Mn Ni Na Ti Cu Mn Sr Ni Ba Ti Mn Ni 0.001-0. 0!$ 0.001$ Dy Ni I Yb Be La Co Cr Ag Sn V Zr Co Cr Ga Ag Be Y V Zr Yb Mo Sn Co Cr Y Yb V Sn Zr Mo Cr Y V Ag Yb Mo La Dy Co Yb Be Cr Ga Zr Eu Y La Cr Yb ¥ Mo Zr Sm Nd Eu Be Co Y Cr V Yb Ga Pb Nd. Cr Mo V Y Ga Sr Pb Cu —— Ga Gr V Zr OFFICIAL USE ONLY
Table 3.—Semiquantitative speetrographic analyses of samples from diamond drill holes Nos 0 1 and 2, Last Chance claim., Beaverhead County, Montana—Continued Diamond Drill Hole No. 2 Footage 273 o 0-274 06 274.6-275.3 275-3-277.0 Over Si Si Si Si Si 1-10* Al K Fe Al K Fe Al K Fe A1K Fe Al K fiJL ik Fe 0-1.1-0ig Na Hg Ca Na Ca Ti Mg Ba Na Mg Ca Ti Na Ca Mg Ba Ti Ca Na Ba Ti Ni Mn Ni Ba Pb Mn Cu Ni Pb Mn Sr Ni Mg Mn Sr Ni .0.00,1-0. 01 Sf Sr Cu Ga Gr V Zr Sr Co Cu Ga Cr Zr ? I Sr Co Ga Cr Zr V Cu Ga Cr Co V I Zr Mo Ga Cr ? Zr Mo ...0,001$ Be Be Ag Be 277.6-28406 Si Al K Ba Na Ca Th Mg Mn Nd Co Eu Fe Ti Ce Gd Cu Pb Cr Ga Sr Ni Sm V I Mo Zr Spectrographers, Charles Annell and Joseph Haffty, U. S. Geological Survey, Washington Laboratory. QFFIGIAI USE OMLY
OHIJ A semiquantitative spectrographic analysis of a selected radio active sample from the southern part of the Last Chance vein also was made by the Geological Survey . The results of the analysis are as follows s O.OX percent Nd 0.1-1.0 percent La 0.05-0.1 percent Ba QoX percent Ca O.OX percent Ce Oo5~l0 percent Sr O e OOX percent Spectrographer, Tennyson Myers U e S 0 Geological Survey , Denver Laboratory LITERATURE CITED Trites, A. F and Tooker E e W 0 1953 Uranium and thorium deposits in east- central Idaho and southwestern Montanas U 0 S. Geol 0 Survey Bull. 98S - H 5 p 0 157-209, OFFICIAL USE ONLY
OFFICIAL USE ONLY APPENDIX A Detailed geologic log of Diamond Drill hole no. 1 9 e „ „ Detailed geologic log of Diamond Drill hole no* 2 . 0 „ Radiometric log of Diamond Drill hole no e 2 . 0 Detailed geologic log of Diamond Drill hole no 0 3
e OFFICIAL USE ONLY
OFFICIAL USE OHLY DRILL HOLE #1 LAST CHANCE CLAIM, BEAVERHEAD COUNTY 5 MONTANA- DMEA-1186X Direction - N e 43 E 0 at 45° inclination M5 Drillers Garlson--& Son,, logged by Sharp and Cavender, USGS 5 8-52 Depth interval Core recovery in feet Soil overburden Fine-grained gray argillite 0 Fractures parallel to hole,, Brown staining in fractures. Bedding 60° to hole. 35 2o Missing,, Lost core and water. Slightly schistose gray argillite. Brown gouge. 0,8 - 35.3 Upper Oo5 f ditto. Then gray to light green fine- grained sandstoneo Bedding 55° to hole. Bedding shown by biotite layers. Brown stained fractures across and parallel to bedding. 30 35.3 - 40.8 Ditto 40.8 - 45o6 Ditto. Fractures cut core at 30° to hole. More fractured at base. 5°3 45*6 - 50.6 Upper 3'-fine-grained sandstone, then gray-green argillaceous sandstone.. Fractures cemented by Iimonite 0 Minor biotite in sediments. Base sandy micaceous. 5oO 50 0 6 - 52.7 Gray-green quartz sandstone. Bleached,, fractures stained Darker at base c 52o7 - 54 Light gray-green quartz sandstone. Fractures 35° to hole. Broken„ Mottled greenish-gray argillaceous sandstone. Broken o Iron-stained fractures,, gfl quartz vein at 56 0 ,6 f at 30° 5 |fl quartz vein at 57'. Darker and micaceous at base 0 35 Fractured gray sandy argillite. 01 \/hite quartz v.ein with chlorite and black iron staining in upper part. Lower part dark gray-green . sandstone Beds 75° to hole* No recovery OFFICIAL USB OHLI
OFFICIAL USE OHLY Depth interval Core recovery in feet Fine-grained gray argillaceous sandstone 0 Beds 70° to hole 0 At 85% J" quartz vein. At 87% coarser-grained gray-green sandstone 3 with muscovite „ At 90% J" quartz vein at 35° to hole.
90,5 100 Green argillite. quartz vein at top* Then fine-grained, gray-green argillite Biotite on bedding and at 65° (good core) to.*core. At 92% quartz and limonite seam. Below quartz fine- grained gray sandstone, with Muscovite„ At 96% Ig" quartz vein?,, g" quartz veins at 96.5% 98*. Bedding 55° to hole. 9*5 Fine gray-green sandstone. Poor bedding. At 102% 2 ! broken, iron-stained zone 0 Minor bleachingo Below fine-grained gray sandstone„ - 119o5 Bark gray sandstone, some muscovite. Few fractures 0 - Poor bedding. Iron-stained fractures. Quartz vein at 114 f . Some 1/8" quartz seams at base, 95 119o5 - 120 Fine-grained, gray argillaceous sandstone. Gray argillite and sandstone, fractured. Sandy at base* Beds 55° to hole. Occasional 1/8U quartz veins. 50 Light gray to gray-green, micaceous, fine-grained sandstone. Good bedding. Iron-stained fractures* Argillite at base. 63 Gray to gray-green micaceous sandstone. Thin n fractures. Broken gray to gray-green micaceous sandstone. Hematite streaks at 138' and 140% 40 Broken gray to light pinkish-gray argillaceous sandstone. Thin gouge seams. .Iron-stained fractures.
Pinkish-green argillite. Broken,, iron stained. Occasional 1/4" vein of quartz. Mica on bedding at 55° to hole. 2,3 Highly broken, fine-grained, light-gray argillite e Clay at base. OFFICIAL USE ONLY
OFFICIAL USE ONLY Depth interval Gore recovery in feet - 164.5 Rubble of fine, iron-stained, light-gray argillite„ 164.5 - 166.5 Rubble of gray-green argillite and vein quartz, 166.5 - 167.5 Ditto Q2 167.5 - 172 Rubble of gray to gray-green argillite. Thin quartz veins. Light gray-green micaceous sandstone. Biotite on bedding at 50° to hole c Highly fractured and iron stained ISO Light gray-green micaceous sandstone. Broken Light-gray argillite. Highly fractured - 192.5 Whitish mottled, highly fractured argillite. Iron oxides in fractures. 192.5 - 193.5 Ditto. Contorted bedding. 193.5 - 204 White fine-grained sandstone. White to buff, iron-stained, fine-grained sandstone, 1/8" quartz veins from 209 ! -214% mostly white. Highly broken. Thin quartz at 213 s . - 216.2 Gray, iron-stained sandstone. 2" quartz vein. 216.2 - 224 White to buff sandstone. At 223.5% quartz vein. Probably narrow contact zone of sheering. (4 ft quartz recovered). Silicified belt of various colors and brown quart, z. - 226.4 Highly broken,, red-stained quartz. 226.4 - 227.1 Broken gray quartz. Some red and brown quartz. 227.1 - 229.2 Ditto, but more highly stained. Shows evidence of faulting and cementing of rubble. 229.2 - 231.2 Rubble of gray, brown, and red quartz. 231.2 -239 Quartz vein. At 231.5 ! out of quartz and into soft material. No core bit resistance. No core, but sludge of stained sand grains- Did not lose water in hole. TOTAL CORE RECOVERED OFFICIAL USE ONU
OFFICIAL USE ONLY Total cored hole—223 5 Total core recovered~-1142 8 Recovery--=51 Hole bottomed at 2.39 oO on August 31,, 1952. 0-26 drilled NX, cased BX 26 - 70 drilled EX, cased AX 70 -239 drilled AX DRILL HOLE #2 LAST CHANCE CLAIM, BEAVBRHEAD COUNTY, MONTANA Direction—-N 40° E5 45° inclination ME Drillerss Carlson & Son, logged by Sharp and Cavender, USGS 5 9 5 10-52 Depth interval Core recovery in feet Overburden soil and Belt quartzite float Light gray to buff, fine-grained sandstone. Iron stained, weathered 5 friable. Mica on bedding at 35° to hole 0 - 50,5 Upper 05 S -ditto* Then—fine-grained, bleached, micaceous, lightly iron-stained sandstone. Zone of gray argillite and fine-grained sandstone,, Beds are 30° to hole 0 Cleavage is 50° to hole,, 50.5 - 6l Soft, gray argillite5 iron-stained fractures at base. Beds 40° to hole. Cleavage 45-50° to hole. Bottom of BX Weathered, light-gray, fine-grained friable sandstone. Iron stained and broken at top. Bedding 30° to hole. 1.2 Fine, light-gray 5 micaceous sandstone. Bedding 33 (top) and 30 (base) and 40° (middle) to hole. Graded bedding -upright 2*4 - 96 Ditto. Thin quartz-hematite vein at base. -97.5 Interlayered sandstone and argillite Beds at 35 3 to hole. Cleavage in argillite is 47° to hole. 97.5 -1095 Upper part is ditto. Center is thin-bedded, micaceous sandstone. Base is bleached sandstone, 1095 -112.1 Upper 1' is fine-grained 5 gray poorly bedded sandstone,, Then 0.75 s cf coarser-grained sandstone with bedding 40° to hole. Then 0 0 3 8 of dark-gray argillite. Below is dark , gray, poorly bedded,, coarse-grained sandstone. OFFICIAL USB OMLY
OFFICIAL USE OljLY Depth interval Gore recovery in feet 112.1 -11?c? Fine-grained, gray sandstone with reddish tinge due to hematite., Bedding 35° to hole. At 113.3% 1/4" quartz seam, crosses bedding at 30°. Associated 2n fractured zone. At 114.7% 1/4" quartz-.hematite vein,, cuts hole at 4.5° to bedding. Sandstone stained, red for 6n across veinlet. Staining trends across hole at 35° Sandstone highly fractured., more micaceous at base. 117.7 -119-9 Sandstone as above. Fractures normal to hole. At base,, rubble zone of fault material,, highly iron stained probably where core was lost. 119.9 -121.2 Sandstone as above. Fractured. 10 121.2 -129*7 Same as above. Darker5 more micaceous at center. Near top., 2—1/4 M quartz veins and a 1" shear zone recemented with Fe20o 0 Shears nearly normal to hole. Veins as previously stated„ Less fracturing in lower 3% bleached along fractures. Sandstone 5 coarse-grained at top and base. Bedding at top 50° to hole* In center, bleaching along fractures. Hematite-filled fractures about 134.5' -145.2 Very fine- to coarse-grained,gray sandstone. Thin quartz vein at 137 J Beds 30° to hole. 44 145-2 -149.3 Ditto, with some very fine-grained,, some very coarse- grained 5 micaceous sandstone 0 2—1/8" altered hematite seams along bedding at base. Cleavage,, rotated 45° from bedding, is 40° to hole. 149.3 -157.5 Gray, thin-bedded sandstone. Bedding at 30° to hole; Fractures at 40° to hole and red stained for 1/2". 157.5 -160 Ditto. 1/2" quartz vein at top 5 at 30° to hole contains specular hematite. 25 -I69o5 Gray sandstone. Fractures cemented with iron oxides. 1/2" quartz., hematite, chlorite vein at 163.8% 30° to hole."Another vein at 165.3'. Bedding 27° to hole. 169.5 -179.5 Ditto. More fractures near top. 36 179*5 -186.4 Ditto. Mica on bedding distinct at top, 25° to hole. Fractures parallel core, OFFICIAL USE ONLI
OFFICIAL USE 'cato 2B Depth interval Core recovery in feet 186,4 -199.7 Sandstone. Bedding indistinct, 1/8" quartz vein at top. Pinkish cast for I 8 below. Core is rubble at base. Quartz veinlet at base 0 34 199.? -200 Ditto,, Cleavage is at 40° to hole. Fine- to coarse-grained, highly broken sandstone. Upper part cemented by iron oxides,, Sandstone of light gray color, with mica on bedding 30° to hole* Highly broken core. -222.1 Light gray to gray, argillaceous sandstone and quartzose sandstone„ Fractures every 3"> cutting 70° to core. At 2195S 2 or 3 small quartz veins. Small fault offsets veins. 222 0 1 -222.8 Ditto. Highly broken,, rubble. Evidence of small quartz vein. 222.8 -229.6 Coarser-grained, bedded sandstone and gray argillite. Broken. 10 2296 -239.6 Argillaceous sandstone 5 light gray, bleached, mottled, irregularly bedded„ Two small quartz veins. Cleavage is 40° to hole, bedding is 20° to hole. 239.6 -249.6 Fine-grained, gray sandstone, bleached at base. Center zone is buff to pink silicified Belt. One or two quartz veinletSo 2496 -2535 Bleached white sandstone, friable, highly broken. Upper part probably in fault zone. 3*9 23.5 -253.8 Ditto. 0,3 Ditto, less broken. 1/4" quartz-hematite vein, altered to porous limonite. -264.6 Ditto at top. Bedding 35° to hole. Silicification in lower foot. Interbed of 4" of bleached sandstone 9 then quartz vein of pinkish- white color. Red hematite staining. 264.6 -266.2 Quartz vein at top. Core shows highly broken quartz vein recemented with specular hematite and 'D-vTw 4- VIT .V-l-rr J__UillWAij.w w . uC/ iitvXj u J-OCi ctia.i-1 liXgtAJ-Jf "reined' 5 . Breccia structure appears 40° to the hole. 1.8 OFFICIAL USE QUIT
OFFICIAL 0SB ONLY Depth interval Core recovery in feefc 266c2 -267.5 Ditto. Very rubbly at tcp c Heavy red iron staining. Bottom is more r""tr*.zose. 26?.5 -269 White Tuggy quartz and specular hematite with red splotches. Base has pieces of unreplaced Belt, further doii alters to white-brown soft sand, -271.2 Zone of quarts vein. Much bleaching, much replaced Belt, Quarts is 60° to hole. Vugs trend at small angle to the hole and follow center of quartz trend. 2.2 2?lo2 -273 Dittoo Much red iron staining„ ?73 -274.6 Ditto, with base mostly rubble of Belt sandstone,, 274 6 -2753 Mostly rubbly sandstone and quartz "pebbles". 0 0 B 2,75*3 -277 White, glassy quartz and relict sandstone. Specular hematite in vugs in. quartz. Hematite ve inlets cut the core at Yarious angles. -277 <.6 Quartz ire in rubble, highly broken,, Shear zone at top cemented with red iron oxide „ 27706 -284.6 Quartz vein, specular hematite rich* Less relict Belt than above. Vuggy, mottled color. Rubbly at base* Out of hard rock'at 279*. No core below 279 Probably soft sandstone 0 1*7 2846 -2856 Quartz vein as above (4W Rest of core is light gray-green argillite, highly veined with brown limonite-stained fractures, Q9 .v;85*6 -294 5 At top is 5" quartz vein, similar to that above— vuggy contains specular hematite. Some unreplaced Belt. Below is bleached light gray, semi-silieified, and friable sandstone, Limonite-stained fractures* 1.8 2:4.05 -298<>5 Some white., bleached friable sandstone, limonite veined. 3/4n quartz veinlet near top* 298o5 -301 Bleached Belt sandstone with limonite veining. Poorer core 0 Bleached white friable Belt, cut and partially replaced by silica., red to white, TOTAL CORE RECOVERED Total hole cored J -277 f Total core recovered - 106.9* Recovery Hole bottomed at 303 l on or about Septo 29, 1952.
U. S. ATOMIC ENERGY COMMISSION Radiometric DDK Log Date: 10-2-52 Last Property-. Chance State: Montana Dist. : Beaverhead DDH no. 2 Location: ,20 Strike: N. 40° E Dip: 44° NE Depth: 302' Water Table Depth: Hetland Log by: Jarrard Driller; Carlson 0)
Q 0) 0) £-, Oa £-, W
IL, cd g 0) K ir
Ta U!ac Xa
Ct
a 'c a a cr~ ITa tdc T
a li tf c. c a tt U G2 Cs ff
NCr.
a K,ir
sC Ps
Ia"c in 0IT t a w o a c 1a°p
"n 0)Q ift a 0)Q Bottom 9275? Meter Reading in Milli Amperes
OFFICIAL USE ONLY DRILL HOLE # 3 - LAST CHANCE CLAIM, BEAVERHEAD COUNTY, MONTANA Direction— N 9 50° E., inclination 45° NE Drillers? Carlson & Son,, Logged by Siarp and Cavender USGS 5 - 26 Soil and. overburden - 95 Soft, fine-grained , gray-white bleached sandstone,, Lost water at 54% never recovered circulation. Pressure lost again at 95 ! BX casing 0-26 ! AX casing 26 s - 60' . Drilling discontinued for the winter at depth of 95 as to have been resumed in spring of 1953 - OFFICIAL USE OIL!