Block P Mine

Site Name

Primary: Block P Mine
Secondary: Wright - Edwards
Secondary: Barker

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Commodity

Primary: Silver
Primary: Lead
Primary: Zinc
Secondary: Gold
Secondary: Copper
Tertiary: Molybdenum
Tertiary: Tungsten

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Location

State: Montana
County: Judith Basin
District: Barker District

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Land Status

Not available

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Holdings

Not available

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Workings

Type: Underground

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Ownership

Owner Name: Asarco (American Smelting And Refining Co.)

Owner Name: Thorsen Brothers And Brazee

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Production

Year: 1948
Time Period: 1915-1948
Mined: 368000.000 mt
Material type: ore

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Deposit

Record Type: Site
Operation Category: Past Producer
Deposit Type: Polymetallic veins
Operation Type: Unknown
Year First Production: 1880
Discovery Year: 1879
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: Y
Deposit Size: M

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Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Northern Rocky Mountains
Physiographic Detail: Little Belt Mountains

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Mineral Deposit Model

Model Name: Polymetallic veins

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Orebody

Form: CRESCENT-SHAPED VEIN

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Structure

Type: R
Description: Zone Of Laccoliths And Other Igneous Intrusions Covering Over 800 Square Km

Type: L
Description: Domal Uplift Caused By Intrusion Of Snow Creek Porphyry, Hughesville Stock With Conjugate Fracture System

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Alterations

Alteration Type: L
Alteration: ARGILLIZATION OF SYENITE PORPHYRY

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Rocks

Name: Quartz Monzonite
Role: Host
Age Type: Associated Rock
Age Young: Pliocene

Name: Quartz Monzonite
Role: Host
Age Type: Host Rock Unit
Age Young: Mississippian

Name: Quartz Monzonite
Role: Host
Age Type: Host Rock
Age Young: Pliocene

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Analytical Data

Not available

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Materials

Ore: Galena
Ore: Marmatite
Ore: Sphalerite
Ore: Pyrite
Ore: Tetrahedrite
Gangue: Rhodochrosite
Gangue: Calcite
Gangue: Barite

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Comments

Comment (Commodity): SULFIDE MINERALS OCCUR IN BANDS, LENSES, AND AS DISSEMINATIONS; ?THE GALENA IS FINE GRAINED, BUT OCCURS AS MASSES. IT CONTAINS A FEW SCATTERED AND ROUNDED BLEBS OF TETRAHERITE AND CHALCOPYRITE. IT ALSO CONTAINS NUMEROUS PYRITE FRAGMENTS WHICH MAY BE AS LARGE AS 1 MM IN DIAMETER. SPHALERITE CONTAINS ABUNDANT CHALCOPYRITE INCLUSIONS. CHALCOPYRITE ALSO OCCURS AS JAGGED GRAINS AND VEINLETS IN GALENA. TETRAHEDRITE OCCURS PREDOMINANTLY AS GRAINS NEAR CHALCOPYRITE, AS INCLUSIONS IN CHALCOPYRITE, AND IN VEINLETS CUTTING PYRITE. THE TETRAHEDRITE IS ASSOCIATED WITH THE OTHER MINERALS OTHER THAN GALENA, BUT OCCURS PREDOMINANTLY WITH THESE OTHER MINERALS WHERE THEY CUT GALENA.? (YOUNG AND OTHERS, 1962) TETRAHEDRITE IS MAIN SILVER-BEARING MINERAL (SPIROFF, 1938). SOME DISSEMINATED PYRITE, MOST SULFIDES CONFINED TO FISSURES OR AT THE CONTACT OF THE SYENITE WITH DIKES. (SPIROFF, 1938).

Comment (Reserve-Resource): ALTHOUGH ORE SHOOTS KNOWN TO PERSIST TO 1400 LEVEL, MINE MAP SHOWS LITTLE STOPING BELOW 1000 LEVEL. ASSUMING A TRIANGULAR ORE SHOOT, 2000 FT ACROSS THE TOP, AND 1000 FT HIGH, REMAINS BELOW THE 1000 LEVEL GIVES THE RESOURCE ESTIMATE. TONNAGE IS BASED ON STOPED AREA/TONNAGE RATIO FOR UPPER PORTIONS OF MINE. ASSUMED GRADE IS ABOUT 20% LESS THAN GRADE OF MOST DEEP PRODUCTION, AS METAL CONTENT IS ASSUMED TO DIMINISH WITH DEPTH.

Comment (Exploration): 1879 - BARKER CLAIM LOCATED. 1880 - WRIGHT AND EDWARDS CLAIMS LOCATED. 1881- GREY EAGLE CLAIM LOCATED AND ALL FOUR CLAIMS PATENTED. UNTIL 1883 - SOME ORE SHIPPED TO SMELTERS BUT MUCH SMELTED LOCALLY. MINING DECLINED UNTIL 1891. 1891 - RAILROAD BRANCH COMPLETED TO BARKER. 1898-1902 - MOST CLAIMS LEASED TO UNITED SMELTING AND REFINING COMPANY. 1902 - T.C. POWER (BLOCK P MINING COMPANY) ACQUIRES BLOCK P. 1911 - 75-TON GRAVITY MILL BUILT. 1920 - MILL CAPACITY INCREASED TO 100 TON/DAY. 1927 - ST. JOSEPH LEAD COMPANY PURCHASES BLOCK P. EXTENSIVE DEVELOPMENT FOLLOWS, WITH RAILROAD REBUILT, 400-TON SELECTIVE FLOTATION MILL BUILT, AND A NEW STEEL HEADFRAME AND TRAMWAY. 1930 - SEPTEMBER, MINING CEASED BECAUSE OF UNECONOMIC CONDITIONS. 1941 - OPERATIONS RESUME. 1943 - OCTOBER, OPERATIONS CEASE. 1944 - MINE AND EQUIPMENT SOLD TO THORSON BROTHERS AND BRAZEE. SELL OFF EQUIPMENT. 1945 - AMERICAN SMELTING AND REFINING COMPANY (ASARCO) BUY MOST HOLDINGS BUT THORSON BROS. AND BRAZEE RETAIN RIGHTS TO MINE ORE FROM THE ADITS ABOVE THE COLLAR OF THE SHAFTS.

Comment (Production): 1915-1948 405,852 TONS OF ORE PRODUCING 3,332.13 OZ. AU, 2,578,224 OZ AG, 775,112 LBS. CU, 42,750,417 LBS. PB, AND 17,848,398 LBS. ZN. (ROBERTSON AND ROBY, 1951).

Comment (Deposit): FISSURES WERE THE MOST IMPORTANT PRODUCERS

Comment (Production): PRODUCTION RECORDS PRIOR TO 1915 MEAGER, BUT PRODUCTION APPEARS TO HAVE BEEN AT LEAST 150,000 TOZ AG AND 3,000,000 LB PB.

Comment (Deposit): ?ORE MINERALS AT THE BLOCK P OCCUR IN VEINS LOCALIZED ALONG TENSION FRACTURES IN A PORPHYRITIC SYENITE PLUG.? (YOUNG AND OTHERS, 1962). ?SHEAR AND TENSIONAL FRACTURES ARE FOUND WITHIN THE MINE. THESE FRACTURES HAVE BEEN MINERALIZED AND WERE FOLLOWED BY DIKES.? (SPIROFF, 1938). ?THE BLOCK P VEIN FORMS A CRUDE SEMI-CIRCLE, ABOUT TWO-THIRDS OF A MILE IN DIAMETER, ENTIRELY WITHIN THE HUGHESVILLE QUARTZ MONZONITE STOCK. SPIROFF (1938) DESCRIBED THE ARCUATE VEIN AS FOLLOWING PORTIONS OF FIVE PLANAR FEATURES. TWO ARE ADJACENT TO THE MAFIC DIKES AND ONE IS PARALLEL TO A NEARBY FELSIC DIKE. WALKER SUGGESTS THAT THE VEIN WAS A CONE SHEET ABOVE A CONCEALED GRANITE PLUTON.? (BAKER AND OTHERS, 1991).

Comment (Location): UTM LOCATION OF BARKER SHAFT

Comment (Workings): VEIN DEVELOPED BY 1484 FT. TWO-COMPARTMENT BARKER SHAFT NEAR GALENA CREEK AT EASTERN END OF VEIN, WRIGHT EDWARDS 320 FT SHAFT ON HILL NEAR WEST END OF VEIN, A 2800 FT ADIT DRIVEN FROM NEAR THE COLLAR OF THE BARKER SHAFT TO THE WRIGHT-EDWARDS SHAFT, AND SEVERAL MINOR ADITS. A TOTAL OF MORE THAN 20,000 FEET OF DRIFTS AND CROSSCUTS MADE BY 1943 (ROBERTSON AND ROBY, 1951). DEVELOPED 1,400+ FEET VERTICALLY AND 4,000 FEET ALONG THE VEIN (SPIROFF, 1938).

Comment (Deposit): Merged Data from Deposit ID's: 10245440 (Grey Eagle) 10196660 (Barker Crosscut of Block P Mine) 10124398 (Equator Tunnel of Block P Mine) 10196718 (Thorson Tunnel of Block P Mine) 10270681 (200-Ft. Level, Wright & Edwards) 10270332 (Wright and Edwards Shaft- Block P) 10245650 (A Tunnel of Block P Mine) 10173138 (B Tunnel of Block P Mine) 10148735 (Maytee Tunnel of Block P Mine) 10221364 (Barker Shaft of Block P Mine)

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References

Reference (Deposit): WITKIND, I. J., 1973; IGNEOUS ROCKS AND RELATED MINERAL DEPOSITS OF THE BARKER QUADRANGLE, LITTLE BELT MOUNTAINS, MONTANA: U.S. GEOLOGICAL SURVEY PROF. PAPER 752, 58 P.

Reference (Production): USGS PROF. PAPER 752, P. 51

Reference (Deposit): ROBERTSON, A. F., AND ROBY, R. N., 1951, MINES AND MINERAL DEPOSITS (EXCEPT FUELS), JUDITH BASIN COUNTY, MONT.: U.S. BUREAU OF MINES INF. CIRC. 7602, 48 P.

Reference (Geology): SPIROFF, KIRIL, 1938, GEOLOGICAL OBSERVATIONS OF THE BLOCK P MINE, HUGHESVILLE, MONTANA: ECONOMIC GEOLOGY, V. 33, NO. 5 P. 554-567.

Reference (Geology): WALKER, G.E., 1991, GEOLOGY OF THE BARKER MINING DISTRICT, JUDITH BASIN AND CASCADE COUNTIES, MONTANA, IN GUIDEBOOK OF THE CENTRAL MONTANA ALKALIC PROVINCE: MONTANA BUREAU OF MINES AND GEOLOGY SPECIAL PUBLICATION 100, P. 29-37.

Reference (Geology): BAKER, D.W., MCBRIDE, GWEN, AND DAHY, JAMES, 1991, FIELD GUIDE LITTLE BELT MOUNTAINS, IN GUIDEBOOK OF THE CENTRAL MONTANA ALKALIC PROVINCE: MONTANA BUREAU OF MINES AND GEOLOGY SPECIAL PUBLICATION 100, P. 145-162.

Reference (Geology): WEED, W.H., 1900, GEOLOGY OF THE LITTLE BELT MOUNTAINS, MONTANA, WITH NOTES ON THE MINERAL DEPOSITS OF THE NEIHART, BARKER, YOGO, AND OTHER DISTRICTS; ACCOMPANIED BY A REPORT ON THE PETROGRAPHY OF THE IGNEOUS ROCKS OF THE DISTRICT, L.V. PIRSSON: U.S. GEOLOGICAL SURVEY 20TH ANNUAL REPORT (1898-1899), PART 3, P. 257-581.

Reference (Economic Factors): YOUNG, F.M., CROWLEY, F.A., AND SAHINEN, U.M., 1962, MARKETING PROBLEMS OF SMALL BUSINESS ENTERPRISES ENGAGED IN LEAD AND ZINC MINING: MONTANA BUREAU OF MINES AND GEOLOGY BULLETIN 30, P. 27.

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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.