T'AlC AND CHLORITE DEPOSITS IN MONTANA by .-J Richard B. Berg .d&&ALihM= SELLa --- , . - • U££J6i'iE!Ii!i!!!W'I!'i!liIleaXZaA$2lC2l$dQJ=.' meA. iiia MEMOIR 45 1979 -- JMONTANA BUREAU OF MINES AND GEOLOGY > A Department of Montana Cottege of Mineral Science and Technology GUNTER00000814 Preface This memoir is one in a series of reports on nonmetallic mineral commodities published by the Montana Bureau of Mines and Geology. The main purpose of this study is to provide information that will be useful to those engaged in explor­ ation for new talc and chlorite deposits. For that reason, mapping of areas that were thought most likely to contain talc was emphasized, as was the mapping and examination of talc prospects and inactive mines that have not been de­ scribed in the literature. In an effort to make this publication more useful to the individual unfamiliaf with talc and chlorite in Montana, published information on all known talc occurrences is also included in abbreviated form. The contributions of the following field assistants were important to the completion of the project and are much appreciated: Will Goldberg (1973t,.Hal Koechlein (1974), Roger Kuhns (1975), Leroy Swanson (1976) and Steve Czehura for a short time in 1977. I enjoyed working with each of them. Sam Maloney, Pete Womack and Bob Nolte were very helpful in shoWing us talc prospects. Ken Wier showed interest in our work in the Greenhorn Range and offered sug­ gestions for the improvement of the geologic map of that area. Review of the manuscript by Keith Papke and Willis Johns resulted in many improvements. Alice Blount of the Newark Museum, Newark, New Jersey, ran infrared scans on samples of stream sediment and soil. She, Bob Root, Dick Olson, Ed Houser and John Brady also provided me with an opportunity to discuss my ideas on the origin of Montana talc deposits. Charles Knowles of the Idaho Bureau of Mines and Geology kindly ran microprobe scans of a talc specimen in an effort to determine the composition of some very small opaque grains. Individuals involved with the operating talc mines showed us their opera­ tions, and perhaps most important, expressed interest in our work. They include Jim Mulryan, Don Kennedy and Max Tilford (Cyprus Industrial Minerals), Tad Dale (Pfizer, Incorporated), John Burk (formerly with Pfizer, Incorporated), Peter Bixby and Van Stewart (Resource Processors, Incorporated), and Carl Hafer (owner of Willow Creek mine!. Richard B. Berg Economic Geologist Montana Bureau of Mines and Geology Butte August n, 1979 GUNTER00000815 Memoir 45 TALC AND CHLORITE DEPOSITS IN MONTANA by Richard B. Berg ...... since 1919 1979 GUNTER00000816 Contents PREFACE ..................................... i R-l1 Prospect east of Beaverhead mine ....... 35 ABSTRACT···· ............................. 1 R-12 Regal (Keystone) mine ................. 35 INTRODUCTION ............................. 1 R-13 American Chemet mine ................ 35/ Location, .................... , ....... , ...... 1 R-14 Estelle (Sweetwater) mine .............. 36 Previous work ........... , ........... , ....... 1 R-15 Smith-Dillon mine ..................... 36 Present work ................................ 1 R-16 Banning-Jones mine .................. 36 COMMERCIAL ASPECTS OF TALC AND R-17 Bozo-Zobo mine ......... , ............ 37 CHLORITE ................................. 2 R-18 Crescent prospect (Timber Gulch The mineral talc ........ , ..... , .......... , ... 2 deposit ................................. 37 The mineral chlorite ..... , .~ ................... 2 R-19 Sauerbier mine .......... : ............ 37 Commercial talc .............................3 R-20 Owen-McGovern prospect ............. 38 Fibrous minerals ........ ; .................... 3 Other talc occurrences ....................... 38 Uses of talc ................................. 3 GREENHORN RANGE ............ " .......... 39 PRODUCTION, MINING AND PROCESSING West of the Ruby River ..................... 39 I)," OF TALC AND CHLORITE ......... , ......... 4 East of the Ruby River and north of Idaho . Major talc producing areas. , .................. 4 Creek .................................. 40 Mining and processing of talc ............... , .. 5 Between Idaho Creek and the North Fork Montana talc production ... , ... , .............. 5 of Greenhorn Creek ...................... 40 I·' GEOLOGY AND MINERALOGY OF TALC GH-28 Ruby claims ........................ 40 AND CHLORITE DEPOSITS ............. : .... 6 GH-30 Doubtful claims ..................... 42 Pre-Belt metamorphic rocks .. , ................ 6 Area south of the North Fork of Greenhorn Mineralogy ..... , ........... , ............. , . 7 Creek ........ , ....................... , . 42 Talc ... , .................................. 7 GH-42 Willow Creek mine (Ruby Ridge Chlorite ............................ , ...... 7 mine) .................................. 43 Associated minerals .......................... 8 GH-43 Claims north of Willow Creek (Adani ORIGIN OF TALC AND CHLORITE ............. 12 and Eve No.1 and No.2). ................. 46 Conditions of formation ...................... 12 GH-45 Talc occurrence south of Virginia City .. 46 Time of formation .......................... ,14 GH-46 Calverts claims .... , . , ............... 46 Stratigraphic and structural control .......... , .14 Other prospects and inactive mines ........... 48 EXPLORATION FOR TALC .................... 15 GRAVELLY RANGE ........................... 49 HIGHLAND MOUNTAINS .. , ................. 19 GR-1 Tait Mountain claims .................. 49 H-1 Golden Antler mine ................. '... 19 GR-2 Cherry Gulch prospect .............. , .50 TOBACCO ROOT MOUNTAINS ............... 21 GR-3 Yellowstone mine .................... 53 TR-l MineraJ Hill prospect .................. 21 GR-4 Queen claim ......................... 55 ,• ~GLJlch - TR-2 Spuhler occurrence ... , ...... , .. 22 GR-5 Burlington Northern mine .............. 55 TR-3 Latest Out mine .... , ................. 22 .GR-6 Tate-bearing conglomerate north of TR-4 Horse Creek prospect ................. 22 Johnny Gulch ........................... 56 TR-5 Bivens Creek prospect ....... , ......... 22 MADISON RA~GE ......... , ................ 57 TR-6 Harris Creek prospect. ................ 24 TR-7 Grandview prospect ......... , ......... 26 HENRYS LAKE MOUNTAINS ................. 58 TR-8 Granite Creek prospect ................ 26 OTHER TALC OCCURRENCES ................ 59 TR-9 Bear claims (Granite Creek mine) ........ 26 0-1 Talc mine south of Helena ............... 59 TR-lO Talc prospect southwest of Ennis ...... 30 0-2 Lynx Creek (Mathews) talc prospect ...... 59 1 RUBY RANGE .............................. 31 OTHER AREAS OF PRE-BELT METAMORPHIC R-1 Ruby Peak occurrence .................. 32 ROCKS .................................. 60 R-2 Spring Creek prospect .................. 32 Blacktail Range ............................. 60 R-3 Gem claim ................. , , ......... 32 Tendoy Mountains .......................... 60 R-4 Whitney claims ........................ 33 Snowcrest Range ........................... 60 R-5 Prospect southwest of Whitney claims. , .. 33 Spanish Peaks area ......................... 61 R-6 Prospect north of Treasure mine ......... 33 Northern part ofthe Gallatin Range ............ 61 R-7 Prospect northeast of Treasure mine .. , ... 33 Beartooth Mountains ........................ 61 R-a Bennett Owen claim .. : ................. 33 Little Belt Mountains .................... , ... 61 R-9 Treasure mine ......................... 34 Other areas of possible pre-Belt rocks .......... 61 R-l0 Beaverhead mine .....................34 REFERENCES ................ , .............. 63 GUNTER00000817 jQt Figures .35 1-Mountain ranges and major roads in area 11-Prospect southwest of Ennis, Tobacco .35 of talc and chlorite occurrences in south- Root Mountains ......................... 30 .35 western Montana ........................ vi 12-Ruby claims, Greenhorn Range ............ 41 .36 2-Plot of compositions of analyzed chlorite .... 10 13-Doubtful claim. Greenhorn Range .......... 43 .36 3-Talc and chlorite OCcurrences in south- 14-Greenhorn claims, Greenhorn Range ........ 44 .36 western Montana ........................ 16 15-Geologic map ot'the area surrounding the :n 4-Horse Creek prospect, Tobacco Root Willow Creek mine ....................... 44 16-Diagrammatic cross section of the talc .n Mountains .............................. 23 5-Cut northwest of Harris Creek, Tobacco deposit at the Willow Creek mine ........... 45 .37 Root Mountains ......................... 25 17-Calverts claims, Greenhorn Range .......... 47 .38 18-Tait Mountain claims (northern part), .38 6-Prospect southeast of Harris Creek, . Tobacco Root Mountains ................. 25 Gravelly Range .......................... 50 .39 19-Tait Mountain claims (southern part), 7 - Southern Granite Creek prospect, .39 Gravelly Range .... :...................... 51 Tobacco Root Mountains ................... 27 20-Generalized geologic map of the Cherry Gulch- 8-Northern Granite Creek prospect, 40 Johnny Gulch area of the Gravelly Range .... 52 Tobacco Root Mountains ................. 27 21-Burlington Northern mine. Gravelly Range ... 54 40 9-Northern cut at Bear claims. Tobacco • 22-lnactive pit on the Queen claim, Gravelly 40 Root Mountains .............. .- .......... 28 Range ............... ',' •. :............... 56 42 10-Southern cut at Bear claims, Tobacco 23- Lynx Creek (Mathews) talc prospect, Root Mountains ......................... 29 Lincoln County