Geology of Uranium and Associated Ore Deposits Central Part of the Front Range Mineral Belt Colorado By P. K. SIMS and others GEOLOGICAL SURVEY PROFESSIONAL PAPER 371 Prepared on behalf of the U.S. Atomic Energy Commission UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thoma~B.Nobn,D~ec~r The U.S. Geological Survey Library catalog card for this publication appears after page 119 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C., 20402 PREFACE This report is bused on fieldwork in the central part of the Front Range mineral belt between 1951 and 1956 by geologists of the U.S. Geological Survey on behalf of the U.S. Atomic Energy Co1nmission. The work was cn.rriecl on by nine authors working in different parts of the region. Therefore, although the senior author is responsible for the sections of the report thn,t are not ascribed to inclividualrnembers, the entire report embodies the efrorts of the group, which consisted of F. C. Armstrong, A. A. Drake, Jr., J. E. Harrison, C. C. Hawley, R. H. l\1oench, F. B. l\1oore, P. K. Sims, E. W. Tooker, and J. D. Wells. III CONTENTS Page Page Abstract------------------------------------------- 1 Uranium deposits-Continued Introduction ______________________________ - _______ _ 2 ~ineralogy-Continued Purpose and scope of report _____________________ _ 2 Zippeite and betazippeite ___________________ _ 39 Geography ____________________________________ _ 2 Schroeckingerite _________________________ --- 39 Previous geologic studies ________________________ _ 3 Thucholite(?) ___ --------------------------- 39 Johannite _________________________________ _ Present investigation ___________________________ _ 4 39 Acknowledgments ______________________________ _ 4 Paragenetic relations of pitchblende to the common History of uranium mining and production ____________ _ 5 vein-forming minerals ______________________ --- 39 Geologic setting ___________________________________ _ 6 General character and structure _______________ --- 41 Rock units ____________________________________ _ 6 Relation of deposits to fault sets _________ -_--- 41 Precambrian rocks _________________________ _ 6 Ore shoots _______ --- --- __________ ---------- 41 Tertiary intrusive rocks ____________________ _ 8 Grade of primary depqsits ____________________ --- 43 Radioactivity of country rocks __________________ _ 9 ~ineralogical and chemical character of wallrocks-- _ 44 Precambrian rocks _________________________ _ 9 Localization of ore ___________________________ --- 44 Thorium- and rare-earth-bearing gneiss and Relation of primary ores to depth _______________ -- 48 migmatite ___________________________ _ 9 Relation of uranium deposits to sulfide mineral zoning ______________________________________ _ Uranium-bearing pegmatite _____________ _ 10 48 Biotite.. m uscovite granite _______________ _ 12 Supergene alteration_---_--- _____ -_-------_-_--- 49 Tertiary intrusive rocks _____________________ _ 13 Structure _____________________________________ _ Relation of alteration products to water table 13 and primary ore ________________________ -- 49 Structure of Precambrian rocks ______________ _ 13 Occurrence of secondary uranium minerals ____ - 50 Form of Tertiary intrusive rocks _____________ _ 14 Grade of secondary deposits ________________ -- 51 Joints-----~------------------------------- 14 Chemical consi::lerations ____________________ _ 51 Faults ___________________________________ _ 15 Origin of uranium deposits ______________________ _ 52 Classification and description ____________ _ 15 Source of uranium ___________________ :.. _____ _ 53 Faults of Precambrian(?) age ________ _ 16 Chemical environment of deposition __________ - 54 Age __________________________________________ _ Faults of Laramide age _____________ _ 18 54 Fault pattern ___________ ---_- __ -- ___ --- 18 Future production __________________ ----_----------- 55 Age and origin of faults _________________ _ 19 ~ine descriptions __________ - ___ - ________ ------------ 55 Summary of geologic history ________________________ _ 20 Ore deposits _______________________________________ _ 21 Central City district _____________________ ------- 55 Structure and general character __________________ _ 21 Quartz Hill-upper Russell Gulch area ________ -- 55 Flack vein ____________________________ _ ~ineralogY------------------------------------ 21 55 Classification of veins __________________________ _ 22 West Flack mine __________________ _ 56 Hypogene mineral zoning _______________________ _ 24 ~ercer County mine ______________ -- 58 Regional zoning_ -' _________________________ _ 24 German and Belcher mines ______________ - 59 Longitudinal zoning of veins ________________ _ 26 Iron mine, by A. A. Drake, Jr ___________ _ 61 Depth zoning _____________________________ _ 26 Jefferson-Calhoun vein _________________ _ 62 Paragenesis of vein minerals _____________________ _ 26 Kirk mine ____________________________ _ 63 Wallrock. alteration, by E. W. Tooker ____________ _ 27 Old Town mine, by A. A. Drake, Jr ______ _ 65 Genesis of sulfide veins _________________________ _ 28 Springdale (Gold Rock) mine, by A. A. Uranium deposits __________________________________ _ 29 Drake, J r ________________________ ---- 67 Abundance and distribution of uranium in veins ___ _ 29 Telegraph mine ________________________ _ 68 Mineralogy ______________________ - ___ ---- ___ --- 32 Wood vein ____________________________ _ 69 Pitchblende _______________________________ _ 32 Eureka Gulch area _______________________ --- 70 Texture ______________________________ _ 32 Carroll mine _________________________ - _ 71 Variation in physical appearance _________ _ 34 Claire ~arie mine __ -------------------- 77 Variation in state of oxidation ___________ _ 35 St. Anthony and R.H.D. mines __________ _ 78 Chemical composition of pitchblende __ ·___ _ 36 Two Sisters mine _____________________ - _ 80 ~in or elements in pitchblende ___________ _ 36 Justice Hill and adjacent areas ______________ _ 82 Torbernite and metatorbernite ______________ _ 38 Bonanza mine-------------~------------ 82 Autunite and metf£-autunite _________________ _ ·as Cherokee vein ________________________ -- 84 Kasolite __________________________________ _ 38 Pewabic tunnel, by A. A. Drake, ·J r __ .:. ___ _ 87 Dumontite ________________________________ _ 38 Silver Hill area _______________________ - _---- 88 Uranophane _______________________________ _ 39 Blackhawk Lode No.2 claim ____________ _ 88 Bayleyite _________________________________ _ 39 Powhatan tunnel, by A. E. Dearth _______ _ 91 v I , VI CONTENTS Mine descriptions-C~:mtinued Page Mine descriptions-Continued Lawson-Dumont-Fall River district, by C. C. Hawley Freeland-Lamartine district, etc-Continued and F. B. Moore _____________________________ _ Crazy G~lmine ___________________________ _ 92 110 Fall River area ____________________________ _ 92 Diamond Mountain mine ___________________ _ 110 Almaden mine _________________________ _ 94 Harrisburg mine ___________________________ _ 111 Golconda tunneL ______________________ _ 94 Lamartine mine ___________________________ _ 111 Mary mine ____________________________ _ 96 Little Johnie group ________________________ _ 111 Lawson area ______________________________ _ 98 Lone Tree mine ___________________________ _ 111 Bellevue-Hudson mine _________________ _ 98 Miller mine _______________________________ _ 111 Jo Reynolds mine ______________________ _ 99 Poor Man mine ____________________________ _ 111 Robineau (Peabody) prospect ___________ _ 101 . Chicago Creek area, by J. E. Harrison and J. D. Other mines _____________________________ ~ __ Wells _______________________________________ _ 101 111 Albro mine _____________ --------- ______ _ 101 AI pine mine _______________________________ _ Golden Calf mine ______________________ _ 111 101 Blackwood mine ___________________________ _ 111 Idaho Springs district, by R. H. Moench _________ _ 103 Bruce mine _______________________________ _ Alma Lincoln mine _________________________ _ 111 103 Brunswick tunneL _________________________ _ 112 Diamond Joe tunnel, by A. A. Drake, Jr ______ _ 104 Chicago mine _____________________________ _ 112 Jennie Lind No. 1 tunneL __________________ _ 104 Dixie mine ________________________________ _ 112 MAB tunneL ________ ~ ____________________ _ 105 Eclipse mine ______________________________ _ 112 New Bedford tunneL ______________________ _ 105 Gomer mine _______________________________ _ 112 Red Jacket mine ___________________________ _ 106 H urn bold t mine ___________________________ _ 112 Shafter mine ______________________________ _ 106 Katie Emmett mine ________________________ _ 112 Stanley mine ______________________________ _ 106 Martha E mine ____________________________ _ Star mine _________________________________ _ 112 107 Muscovite tunneL _________________________ _ 113 Sunnyside mine, by J. E. Harrison and R. H. Orinoco tunneL ___________________________ _ Moench ________________________________ _ 113 108 Silver Link tunneL _____________· ___________ _ 113 Freeland-Lamartine district, by J. E. Harrison and Tyone mine _______________________________ _ 113 J. D. Wells ___________ ----------------------- 110 Wall ace tunnel ____________________________ _ 114 Ariadne mine ______________________________ _ 110 Literature cited _______________________ ·____________ -· Belle Creole