Flathead Mines

Site Name

Primary: Flathead Mines
Secondary: Hog Heaven Project

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Commodity

Primary: Silver
Primary: Lead
Secondary: Gold
Secondary: Zinc
Secondary: Copper

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Location

State: Montana
County: Flathead
District: Hog Heaven District

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Land Status

Land ownership: Mixed
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

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Holdings

Type: State Lease
Type: Private Lease

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Workings

Type: Surface

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Ownership

Owner Name: Coca Mines Inc.
Company ID: 2400284
Percent: 100.0
Home Office: Colorado
Info Year: 1985

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Production

Year: 1930
Time Period: 1928-1930
Description: Tonnes Of Ore Containing 46 Million Grams Of Silver (2,600 Gm/T). Estimated Total Production Between 1928-30 And 1934-64 Is 209,000 Tonnes Which Yielded 210 Million Grams Of Silver, 93,000 Grams Of Gold, 10.4 Million Kilograms Of Lead, And 272 Thousand Kilograms Of Copper From Both Surface And Underground Workings
Year: 1930
Time Period: 1928-1930
Description: Total Production Between 1928-30 By The Anaconda Co. Or It's Leasees Was 18,000

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Deposit

Record Type: Site
Operation Category: Plant
Deposit Type: Hot-spring Au-Ag (Pb)
Plant Type: Beneficiation (Mill)
Plant Subtype: Hydromet
Operation Type: Surface-Underground
Mining Method: Unknown
Year First Production: 1928
Discovery Year: 1913
Years of Production:
Organization:
Significant: Y
Deposit Size: S

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Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Northern Rocky Mountains

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Mineral Deposit Model

Model Name: Hot-spring Au-Ag

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Orebody

Form: PODS, SHOOTS; IRREGULAR

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Structure

Type: L
Structure: WEST-TRENDING FRACTURES

Type: R
Structure: SHRODER CREEK FAULT, ELK MOUNTAIN ANTICLINE

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Alterations

Alteration Type: L
Alteration: SILICIFICATION, ALUNITIZATION; INTENSE SILICIFICATION

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Rocks

Name: Argillite
Role: Host
Age Type: Host Rock
Age Young: Neoproterozoic

Name: Latite
Role: Host
Age Type: Host Rock
Age Young: Pliocene

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Analytical Data

Not available

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Materials

Ore: Argentite
Ore: Bornite
Ore: Enargite
Ore: Silver
Ore: Sphalerite
Ore: Matildite
Ore: Pyrite
Ore: Galena
Ore: Marcasite
Gangue: Alunite

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Comments

Comment (Reserve-Resource): M1C1=M2C1+M3C1. RESERVES WERE DETERMINED AFTER DRILLING OVER 400 HOLES, AND SAMPLING THE OLD UNDERGROUND WORKING AT THE MAIN MINE. RECOVERABLE INDICATED ORE WITH A 15% DILUTION FACTOR EQUALS 3,651,000 MT GRADING 109 GM SILVER PER METRIC TON AND 0.48 GM GOLD PER METRIC TONNE. RESERVES AS OF DEC. 31, 1984 FROM COCA MINES INC. 1984 ANNUAL REPORT, P. 6. COCA MINES INC., HOG HEAVEN OPTIMIZATION STUDY.

Comment (Economic Factors): UNIT PRODUCTION COSTS WILL VARY OVER THE LIFE OF THE MINE: 1985-86 1987-88 1989-90 1991-96 MINING 3.00 5.25 7.50 3.00 MILLING 15.00 15.00 15.00 12.50 TOTAL $18.00 $20.25 $22.50 $15.50 SURFACE MINE INVESTMENTS YEAR COST TOTALS ACQUISITION UNKNOWN FEE SIMPLE EXPLORATION 1975 $250,000 1976 250,000 1977 250,000 1978 250,000 1979 1,200,000 1980 1,200,000 1981 1,200,000 $4,600,000 DEVELOPMENT 1979 $300,000 1980 300,000 1981 300,000 1982 100,000 1983 100,000 1984 500,000 1990 300,000 $1,900,000 MINE PLANT AND EQUIPMENT 1983 3,300,000 1984 7,700,000 $11,000,000 MINE INFRASTRUCTURE 1983 160,000 1984 640,000 800,000 MINE WORKING CAPITAL* 1985 79,000 1986 79,000 1987 137,000 1988 137,000 1989 194,000 1990 194,000 1991 79,000 1992 79,000 1993 79,000 1994 79,000 1995 79,000 1996 79,000 1,294,000 TOTAL 19,594,000 *APPROXIMATE % OF FIGURES GIVEN IN APPENDIX-A, MINE AND MILL WORKING CAPITAL-AS SHOWN FOR EACH YEAR OF PRODUCTION. AVERAGE PRODUCTION COST FOR THE MAIN MINE OVER THE SIX YEAR LIFESPAN IS $5.17 PER METRIC TONNE.

Comment (Production): DORE ASSUMED TO BE 95% SILVER.

Comment (Economic Factors): THE MAIN MINE ORE CONSISTS OF A MIXED OXIDE-SULFIDE MATERIAL THAT BOTH FLOTATION AND CYANDIATION WILL BE USED TO RECOVER SILVER VALUES. ABOUT 70% SILVER RECOVERY IS EXPECTED. OLE HILL ORE CONSISTS OF A HIGHLY OXIDIZED ORE WHICH IS AMENABLE TO CYANIDATION, WITH AN EXPECTED 80% RECOVERY. MAIN MINE ORE RUNS 152 GM/MT AG, 0.44 GM/MT AU OLE MINE ORE RUNS 63 GM/MT AG, 0.39 GM/MT AU

Comment (Geology): BOTH SEDIMENTARY AND IGNEOUS ROCKS ARE FOUND WITHIN THE HOG HEAVEN DISTRICT. THE SEDIMENTARY ROCKS ARE PRINCIPALLY PRECAMBRIAN METASEDIMENTS OF THE BELT SERIES. AT LEAST TWO FORMATIONS ARE INCLUDED: THE BURKE FM FOUND EAST, WEST, AND NORTHWEST OF THE FLATHEAD MINE. THIS FM IS A GREEN-GRAY, THIN-BEDDED ARGILLITE; AND THE WALLACE GROUP FOUND NORTHEAST OF THE MINE. IT IS A THIN-BEDDED, NONCALCAREOUS LIGHT-GREY SHALE. THE ROCKS ARE NOT FOUND AT THE MINE, BUT ARE INCORPORATED AS CLASTS WITHIN YOUNGER LITHIC PORPHYRY AND TUFF UNITS. TWO SEPARATE PORPHYRY UNITS ARE RECOGNIZED AT THE MINE BECAUSE OF THEIR FELDSPAR PHENOCRYST MINERALOGY: A POTASSIC-RHYODACITE IS THE OLDER UNIT. IT IS INTENSELY ALTERED AND CONTAINS MORE AND LARGER SANADINE PHENOCRYSTS. THE YOUNGER COMPARATIVELY FRESHER UNIT IS A SODIC-RHYODACITE IN WHICH SANADINE IS SUBORDINATE TO THE PLAGIOCLASE. THIN INTERBEDS OF TUFF INDICATE THE ATTITUDE OF THE RHYODACITE.

Comment (Geology): PRIMARY ORE MINERALS ARE GALENA, MATILDITE, AND MINOR ENARGITE, AND SPHALERITE. SECONDARY MINERALS ARE ARGENTITE, COVELLITE, AND MARCASITE. GANGE MINERALS ARE QUARTZ, PYRITE, BARITE, ALUNITE, AND JAROSITE. HIGH GRADE DEPOSITS ESSEN- TIALLY ARE MINED OUT.

Comment (Ownership): THE ORIGINAL MINE WAS OWNED AND OPERATED BY ANACONDA CO. THIS COMPANY OPERATED OR LEASED THE MINE FROM 1928 THROUGH 1964. CONGDON AND CAREY CO., NOW COCA MINES, LEASED THE PROPERTY FROM ANACONDA AND BURLINGTON NORTHERN IN 1975. THEY THEN SUBLET THE PROPERTY TO CANADIAN SUPERIOR IN 1979. IN MAY OF 1982, THE PROPERTY WAS RETURNED TO COCA MINES. COCA MINES CONTROLS 111/2 SECTIONS (2,980 HECTARES) IN THE HOG HEAVEN AREA, ALL OF WHICH IS LEASED FROM THE STATE OF MONTANA, THE BURLINGTON NORTHERN RAILWAY, AND ANACONDA MINERALS CORP.

Comment (Production): PRODUCT OUTPUT FOR SILVER USING 70% OF 152 GM/MT SILVER AND 907 TONNES PROCESSED PER DAY, 365 DAYS PER YEAR MAIN MINE. PRODUCT OUTPUT FOR GOLD USING 70% OF 0.44 GM/MT GOLD AND 907 TONNES PROCESSED PER DAY, 365 DAYS PER YEAR MAIN MINE OLE MINE PRODUCT OUTPUT FOR SILVER AT 63 GM/MT AND 80% RECOVERED FROM 907 TONNES PER DAY OLE MINE PRODUCT OUTPUT FOR GOLD AT 0.39 GM/MT AND 80% RECOVERED FROM 907 TONNES PER DAY. ORE FROM OLE MINE HIGHLY OXIDIZED AND DOES NOT NEED FLOTATION STEP.

Comment (Geology): THE ORIGIN OF THE ORE BODY AT THE FLATHEAD MINE INDICATES A LOW TEMPERATURE HOT SPRING ENVIRONMENT, PROBABLY ASSOCIATED WITH AN ANCIENT VOLCANIC VENT, WHERE METEORIC WATER MIXED WITH RISING METAL-BEARING SOLUTIONS. FRACTURING HAS PLAYED A LARGE PART IN THE DEVELOPMENT OF THE ORE, WHICH LARGELY OCCURS IN VEINS. THE FRACTURES ACTED AS AVENUES FOR THE ORE BEARING FLUIDS. OPEN SPACE FILLING WAS THE DOMINANT METHOD OF ORE EMPLACEMENT. THE VOLCANICS ARE TERTIARY IN AGE AND CONTAIN CLASTS OF PRECAMBRIAN METASEDIMENTS OF THE BURKE FORMATION AND THE WALLACE GROUP. THE VOLCANICS GENERALLY DIP 14-45 DEGREES SOUTH.

Comment (Deposit): Merged data from Deposit ID's 10173155 (West Flathead Mine), 10071341 (West Flathead Mine), and 10071342 (Flathead Mine)

Comment (Deposit): MOST PHENOCRYSTS (BOTH NUMEROUS MODERATELY-DEVELOPED PLAGIOCLASE AND LESSER BUT LARGER, WELL DEVELOPED SANIDINE) WERE PARTLY OR WHOLLY REMOVED AND SOME WERE REPLACED BY BARITE, QUARTZ, OR SULFIDES (SHENON AND TAYLOR, 1936) UNIQUE ?BEIDELLITE? OR FUMEROLE MUD IS FOUND IN IRREGULAR BODIES OR ALONG FRACTURES. (SHENON AND TAYLOR, 1936) CELLULAR STRUCTURE - FORMED WHEN FELDSPARS WERE LEACHED LEAVING VOIDS THEN ENTIRELY OR PARTLY FILLED WITH BARITE, QUARTZ, CLAY, OR IRON OXIDES - DEFINES THE LIMITS OF THE ORE BODY ?FISSUREE VEINS AND PODS IN ALTERED PORPHYRITIC LATITE STOCK INTRUSIVE INTO RAVALLII GROUP (ZARTMAN AND STACEY)

Comment (Workings): OPENED BY FIVE TUNNEL LEVELS AND DRIFTS; SQUARE SET STOPING. PRODUCED 30 TO 40 TONS SILVER ORE PER DAY THAT WAS SHIPPED TO THE WASHOE SMELTER. AND 40 TO 50 TONS PER DAY LEAD-SILVER ORE THAT WAS SHIPPED TO THE EAST HELENA SMELTER (MBMG MINERAL PROPERTY FILES) NO. 1 (UPPER) TUNNEL, NO. 2 (INTERMEDIATE) TUNNEL, AND NO. 3 (LOWER) TUNNEL. UPPER TUNNEL IN 1930?S HAD 1,700 FT OF DRIFTS AND CROSSCUTS (AND WITH STOPES); 1,300 FT ON THE INTEREMEDIATE LEVEL (WITH STOPES) ; AND 1,250 FT ON THE LOWER LEVEL. ORE BODY DEVELOPED (IN THE 1930?S) TO A WIDTH OF 150 FEET AND LENGTH OF 400 FEET; EXPLORED IN THE 1930?S TO A DEPTH OF 150 FEET. (SHENON AND TAYLOR, 1936).

Comment (Exploration): 1913 - INITIAL DISCOVERY BY THE ANACONDA COMPANY. 1928 - LESSEES DRIFTED TO THE ORE BODY. 1929 - LEASE EXPIRED; ANACONDA COMPANY TOOK OVER. 1930 - WORK SUSPENDED. 1934 - MINE RE-OPENED. 1937 - ANACONDA QUIT MINING. 1946 - ?IDLE SINCE 1946? 1958-1976 - PROPERTY LEASED PROPERTY. 1963 -1982 OPERATED BY WAINO LINDBOM, LESSEE FROM ANACONDA. 1960?S FLATHEAD MINES HELD SHORT-TERM LEASE WITH ANACONDA COMPANY; SHIPPED ?SUBSTANTIAL? ORE. 1974 - PREDECESSOR TO COCA MINES (CONGDON AND CAREY, LTD. ?) LEASED SITE FROM ANACONDA. 1975 - OPEN PIT MINE PROPOSED 1982 - COCA REGAINED OPERATING CONTROL OF 10.5 SECTIONS AT HOG HEAVEN FROM SUPERIOR OIL COMPANY. 1983-1988 - COCA MINES PROPOSED OPEN PIT USING A CYANIDE-FLOTATION PROCESS MNING 4,000 TO 5,000 TONS PER DAY.

Comment (Economic Factors): 1928-1930 20,000 TONS ORE YIELDED 1,500,000 OZ AG; 1928 - X00 TONS ORE 1929 - 10,000 TONS ORE YIELDED 900,000 OZ AG 1930 - 10,000 TONS ORE YIELDED 500,000 OZ AG 1934-1946 - 3,000,000 OZ AG PRODUCED 1928 TO 1946 - 248,402 TONS ORE YIELDED 3,379.53 OZ AU, 6,926,406 OZ AG, 631,125 LBS CU, 23,628,602 LBS PB, AND 3,500 LBS ZN (TOTAL OF $6,033,622). RATIO OF SILVER TO LEAD 10:1 TO 7:1. ESTIMATED TOTAL PRODUCTION OF SILVER WAS 8.8 MILLION OUNCES IN A 20-YEAR PERIOD. RESERVES ESTIMATED BY COCA MINES IN 1984 AS 3,000,000 TONS GRADING 6.93 OZ AG, AND 0.014 OZ AU; OPEN-PIT RESERVES 1,314,000 TONS GRADING 5.37 OZ AG, AND 0.014 OZ AU; UNDERGROUND RESERVES WERE 623,000 TONS GRADING 11.24 OZ AG AND 0.007 OZ AU. OPEN-PIT RESERVES ALSO ESTIMATED AT 1.8 MILLION TONS AT 6 OPT AG. RESERVES FROM A COCA MINES 1989 FIRST QUARTER REPORT: PROVEN: 2,891,940 TONS OF 4.88 OPT AG; 14,552,000 CONTAINED OZ AG; 0.018 OPT AG; 54,000 CONTAINED OZ; PROBABLE: 904,200 TONS OF 10.40 OPT AG; 9,404,000 CONTAINED OZ AG; 0.020 OPT AU; 18,000 CONTAINED OZ; POSSIBLE: 450,000 TONS OF 9.17 OPT AG; 4,127,000 SONTAINED OZ AG; 0.006 OPT AU; 3,000 CONTAINED OZ.

Comment (Reference): JOHNS, W. M., 1970, GEOLOGY AND MINERAL DEPOSITS OF LINCOLN AND FLATHEAD COUNTIES, MONTANA: MONT. BUR. MINES GEOL. BULL. 79, 182 P.?SHENON, P.J., AND TAYLOR, A.V. JR., 1936, GEOLOGY AND ORE OCCURRENCE OF THE HOG HEAVEN MINING DISTRICT, FLATHEAD COUNTY, MONTANA: MBMG MEMOIR 17, 26 P.?SAHINEN, U.M., JOHNS, W.M., AND LAWSON, D.C., 1965, GEOCHEMICAL RECONNAISSANCE STREAM-SAMPLING IN FLATHEAD AND LINCOLN COUNTIES, MONTANA: MBMG BULLETIN 48, 16 P.?YOUNG, F.M., CROWLEY, F.A., AND SAHINEN, U.M., 1962, MARKETING PROBLEMS OF SMALL BUSINESS ENTERPRISES ENGAGED IN LEAD AND ZINC MINING: MBMG BULLETIN 30, P. 20.?LANGE, I.M., AND ZEHNER, R.E., 1989, ISOTOPE DATA, AGES, AND GEOLOGY OF THE HOG HEAVEN VOLCANIC FIELD, NORTHWESTERN MONTANA: ISOCHRON/WEST, V. 54, P. 8-10.?SHENON, P.J., 1935, GENESIS OF ORE AT THE FLATHEAD MINE, NORTHWESTERN MONTANA: ECONOMIC GEOLOGY AND THE BULLETIN OF THE SOCIETY OF ECONOMIC GEOLOGISTS, V. 30, NO. 6, P. 585-603.?

Comment (Deposit): ORE BODY SHAPED LIKE "INVERTED MEXICAN HAT". "BRIM" IS ZONE OF INTENSE SUPERGENE ENRICHMENT, "CROWN" IS FILLED WITH VEINS AND PODS OF PRIMARY ORE SHOWING SOME ENRICHMENT. MAIN VEIN IS NEARLY VERTICAL AND BISECTS "CROWN".; ROUGHLY ELLIPTICAL IN UPPER PORTION AND THEN ?MOLAR TOOTH? WITH ROOTS DOWNWARD ON THE LOWER LEVEL (SHENON AND TAYLOR, 1936)

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References

Reference (Reserve-Resource): COCA MINES INC. 1984 ANNUAL REPORT, P.6.

Reference (Deposit): COCA MINING COMPANY. MINE/DEPOSIT FILE REPORT-FLATHEAD MINES, POLSON, MT. FINAL REPORT, U.S. BUREAU OF MINES CONTRACT NO. S0221028, MARCH 1983.

Reference (Deposit): SHENON, P.J., 1935, GENESIS OF ORE AT THE FLATHEAD MINE, NORTHWESTERN MONTANA: ECONOMIC GEOLOGY AND THE BULLETIN OF THE SOCIETY OF ECONOMIC GEOLOGISTS, V. 30, NO. 6, P. 585-603.

Reference (Deposit): CAREY, C. C. ALTERATION PETROLOGY AND MINERALIZATION OF THE HOG HEAVEN MINING DISTRICT, MT. MS THESIS, UNIV. OF MONTANA, 1981.

Reference (Deposit): MONTANA BUREAU OF MINES AND GEOL. BULLETIN 95, 1975, P. 8.

Reference (Deposit): MONTANA BUREAU OF MINES AND GEOL. MEMOIR 31, 1949, P. 24.

Reference (Deposit): LANGE, I.M., AND ZEHNER, R.E., 1989, ISOTOPE DATA, AGES, AND GEOLOGY OF THE HOG HEAVEN VOLCANIC FIELD, NORTHWESTERN MONTANA: ISOCHRON/WEST, V. 54, P. 8-10.

Reference (Deposit): SAHINEN, U.M., JOHNS, W.M., AND LAWSON, D.C., 1965, GEOCHEMICAL RECONNAISSANCE STREAM-SAMPLING IN FLATHEAD AND LINCOLN COUNTIES, MONTANA: MBMG BULLETIN 48, 16 P.

Reference (Deposit): SHENON, P.J., AND TAYLOR, A.V. JR., 1936, GEOLOGY AND ORE OCCURRENCE OF THE HOG HEAVEN MINING DISTRICT, FLATHEAD COUNTY, MONTANA: MBMG MEMOIR 17, 26 P.

Reference (Deposit): YOUNG, F.M., CROWLEY, F.A., AND SAHINEN, U.M., 1962, MARKETING PROBLEMS OF SMALL BUSINESS ENTERPRISES ENGAGED IN LEAD AND ZINC MINING: MBMG BULLETIN 30, P. 20.

Reference (Deposit): JOHNS, W. M., 1970, GEOLOGY AND MINERAL DEPOSITS OF LINCOLN AND FLATHEAD COUNTIES, MONTANA: MONT. BUR. MINES GEOL. BULL. 79, 182 P.

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Principal Gold Districts of Montana

In Montana, 54 mining districts have each have produced more than 10,000 ounces of gold. The largest producers are Butte, Helena, Marysville, and Virginia City, each having produced more than one million ounces. Twenty seven other districts are each credited with between 100,000 and one million ounces of gold production. Read more: Principal Gold Districts of Montana.