STUDIES RELATED TO WILDERNESS PRIMITIVE AREAS BEARTOOTH AREA, MONTANA AND WYOMING GEOLOGICAL SURVEY BULLETIN 1391-F Mineral Resources of the Bear tooth Primitive Area and vicinity, Carbon, Park, Still water, and Sweet Grass Counties, Montana, and Park County, Wyoming. By FRANK S. SIMONS and THEODORE J. ARMBRUSTMACHER, U.S. GEOLOGICAL SURVEY and by RONALD M. VAN NOY, NICHOLAS T. ZILKA, FRANK E. FEDERSPIEL, and JAMES RIDENOUR, U.S. BUREAU OF MINES With a section on INTERPRETATION OF AEROMAGNETIC DATA By LENNART A. ANDERSON, U.S.GEOLOGICAL SURVEY STUDIES RELATED TO WILDERNESS PRIMITIVE AREAS GEOLOGICAL SURVEY BULLETIN 1391-F An evaluation of the mineral potential of the area UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1979 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY H. William Menard, Director Library of Congress Cataloging in Publication Data Main entry under title: Mineral resources of the Beartooth Primitive Area and vicinity, Carbon, Park, Stillwater, and Sweet Grass Counties, Montana, and Park County, Wyoming. (Studies related to wilderness primitive areas) (Geological Survey Bulletin 1391-F) Supt. of Docs, no.: I 19.3:1391-F Bibliography: p. 114 1. Mines and mineral resources Montana. 2. Mines and mineral resources Wyoming Park Co. I. Simons, Frank Stanton, 1917- II. Series. HI. Series: United States Geological Survey Bulletin 1391-F QE75.B9 no. 1391-F [TN24.M9] 55?!3'08s [553'.09786'6] 76-608390 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock No. 024-001-03138-8 STUDIES RELATED TO WILDERNESS PRIMITIVE AREAS In accordance with the provisions of the Wilderness Act (Public Law 88-577, September 3, 1964) and the Conference Report on Senate bill 4, 88th Congress, the U.S. Geological Survey and the U.S. Bureau of Mines are making mineral surveys of wilderness and primitive areas. Areas officially designated as "wilderness," "wild," or "canoe" when the act was passed were incorporated into the National Wilderness Preservation System. Areas classed as "primitive" were not included in the Wilderness System, but the act provides that each primitive area be studied for its suitability for incorporation into the Wilderness System. The mineral surveys constitute one aspect of the suitability studies. This report discusses the results of a mineral survey of the Beartooth Primitive Area and vicinity, Carbon, Park, Stillwater, and Sweet Grass Counties, Mont., and Park County, Wyo., that may come under discussion when the area is considered for wilderness designation. CONTENTS Page Summary..................................................................................................................... Fl Introduction................................................................................................................. 3 Previous investigations................................................................................................. 11 Present investigation and acknowledgments................................................................ 12 Geology and mineral resources, by Frank S. Simons and Theodore J. Armbrustmacher........................................................................... 15 Geology................................................................................................................ 15 Precambrian W rocks.................................................................................... 15 Granitic gneiss........................................................................................ 15 Amphibolite and hornblende gneiss....................................................... 24 Biotite schist........................................................................................... 25 Siliceous metasedimentary rocks............................................................ 27 Feldspathized gneiss............................................................................... 27 Ultramafic rocks..................................................................................... 29 Hornfels................................................................................................. 29 Stillwater Complex................................................................................. 30 Quartz monzonite................................................................................... 31 Precambrian W, X, Y, and Z........................................................................ 31 Mafic dikes............................................................................................. 31 Paleozoic rocks.............................................................................................. 34 Mesozoic rocks.............................................................................................. 34 Tertiary rocks................................................................................................ 35 Intrusive rocks........................................................................................ 35 Volcanic rocks........................................................................................ 36 Quaternary deposits....................................................................................... 37 Glacial deposits...................................................................................... 37 Morainal deposits........................................................................... 37 Glacial till....................................................................................... 38 Rock glaciers.......................................................................................... 39 Talus...................................................................................................... 39 Alluvium................................................................................................ 39 Landslide deposits.................................................................................. 39 Felsenmeer............................................................................................. 40 Structure........................................................................................................ 40 Interpretation of aeromagnetic data by Lennart A. Anderson..................... 43 Mineral resources................................................................................................ 47 History and production................................................................................ 47 Sampling and analytical program................................................................. 49 Results of stream-sediment sampling............................................................ 51 Results of rock sampling.............................................................................. 65 Sampling of mineralized or altered rocks.............................................. 72 Sampling of apparently typical unaltered rocks.................................... 73 Summary of sampling results................................................................ 81 Nonmetallic or industrial minerals and materials......................................... 83 Petroleum and natural gas ........................................................................... 83 Coal.............................................................................................................. 84 Geothermal energy....................................................................................... 84 VI CONTENTS Economic appraisal, by Ronald M, Van Noy, Nicholas T. Zilka, Frank E. Feder- Pa8« spiel, and James Ridenour.............................................................................. F84 Setting................................................................................................................... 84 Commodities.......................................................................................................... 85 Goose Lake area............................................................................................. 86 Copper King claim ................................................................................. 98 Copper Glance claim .............................................................................. 99 Red Lodge mining district.............................................................................. 100 Hellroaring group.................................................................................... 102 Little Nell group..................................................................................... 108 Four Chromes group............................................................................... Ill Edsel claim... Ill Stillwater district. 111 Conclusions........................ 113 References cited................. 114 Index................................ 121 ILLUSTRATIONS Page PLATE 1. Generalized geologic and total intensity aeromagnetic map of the Beartooth Primitive Area and vicinity, Montana and Wyoming .................................................................................................. In pocket 2. Sample locality map of the Beartooth Primitive Area and vicinity, Montana and Wyoming............................................................. In pocket FIGURE 1. Index map of Montana and parts of Wyoming and Idaho, showing location of Beartooth study area........................................................ F3 2. Index map of the Beartooth study area and vicinity, showing principal drainages and other topographic