Troy

Site Name

Primary: Troy
Secondary: Troy Project
Secondary: Spar Lake
Secondary: Old Troy Mine

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Commodity

Primary: Silver
Primary: Copper
Tertiary: Lead

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Location

State: Montana
County: Lincoln
District: Troy

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Land Status

Land ownership: National Forest
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.
Administrative Organization: Kootanai National Forest

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Holdings

Type: Patented

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Workings

Type: Underground

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Ownership

Owner Name: Revett Silver
Percent: 100.0
Home Office: Montana
Info Year: 2009
Years: 1999 -

Owner Name: Kennecott Minerals Corp.
Company ID: 2401467
Percent: 25.00
Home Office: New York
Info Year: 2005
Years: 1963 - 1999

Owner Name: Asarco (American Smelting And Refining Co.)
Company ID: 2401467
Percent: 75.00
Home Office: New York
Info Year: 2005
Years: 1973 - 1999

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Production

Year: 1993
Time Period: 1981-1993
Material type: 44.4 million ounces of silver and 180,000 tons of copper
Year: 1984
Description: 17200000 Kilograms Of Copper
Year: 1984
Description: 4269000 Ounces Of Silver
Year: 1983
Description: 14736000 Kilograms Of Copper
Year: 1983
Description: 3963700 Ounces Of Silver
Year: 1982
Description: 16314000 Kilograms Of Copper
Year: 1982
Description: 4210699 Ounces Of Silver
Year: 1981
Description: Produced After Refining Kilograms Of Cu 2906299 Kilograms Of Copper
Year: 1981
Description: Produced After Refining.Ounces Of Silver 764500 Ounces Of Silver
Year: 1993
Description: Ag 812000 Oz

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Deposit

Record Type: Deposit
Operation Category: Producer
Deposit Type: Sediment-hosted Cu, Revett
Plant Type: Beneficiation (Mill)
Plant Subtype: Flotation
Operation Type: Underground
Mining Method: Open Stope - Room and Pillar
Milling Method: Flotation
Year First Production: 1981
Discovery Year: 1963
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

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Mineral Deposit Model

Model Name: Sediment-hosted Cu, Revett

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Orebody

Form: Three zones up to 60 ft thick, disseminated and stratabound.

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Structure

Type: L
Structure: East Fault

Type: L
Structure: BULL LAKE FAULT

Type: R
Structure: SPAR LAKE SYNCLINE

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Alterations

Alteration Type: L
Alteration: calcite

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Galena
Ore: Covellite
Ore: Silver
Ore: Chalcopyrite
Ore: Chalcocite
Ore: Bornite
Gangue: Barite
Gangue: Quartz
Gangue: Calcite

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Comments

Comment (Production): 1981-1993 production from Asarco Inc. 1981-93 SEC Form 10K.

Comment (Exploration): From Boleneus and other (2005): C. Weatherell (Bear Creek Mining Co.) recognized stratabound mineralization in 1963. This led to regional exploration program in 1964 and discovery of many other Cu-Ag occurrences. In 1964-1972, 112 diamond drill holes and 6200 ft of underground workings and geologic studies were completed. In 1973, the property was leased to Asarco Inc. The core claim block was patented in 1977. In 1979, mining and environmental plans were approved and access tunnel and plant construction began. In 1981, production began. In 1982, the mine reached full production level of 8,500 tons/day using trackless room-and-pillar mining method.

Comment (Production): From Revett Minerals (2009) Production Rate: 4,400 tons per day ore (avg. at planned production) 1.5 million oz. Silver per annum 15.5 million pounds Copper per annum

Comment (Reserve-Resource): See page vii in Reipas and Couture (2005) for Cu and Ag tonnage and grade for each type of resource category. Proven - 1.47 opt Ag, 0.69 % Cu Probable - 1.69 opt Ag, 0.61% Cu Measured - 1.51 opt Ag, 0.76% Cu Indicated - 1.69 opt Ag, 0.64% Cu Inferred - 1.67 opt, 0.36% Cu

Comment (Reserve-Resource): REC 2-RESERVES & GRANDES FROM ASARCO INC. 1984 AR P. 12.

Comment (Production): From Reipas and Couture (2005, p. v.): "ASARCO leased the Troy Project from Kennecott in 1973 with plans to build a mine. Underground production began in 1981 and lasted for a period of 12 years ending in 1993. The mine produced at a nominal rate of 8,500 tons per day which yielded a total of 44.4 million ounces of silver and 180,000 tons of copper upon closure in 1993."

Comment (Reserve-Resource): Portergeo.com.au lists the "pre-mining geological reserve" as: 58 Mt @ 0.76% Cu, 54 g/t Ag, to 64 Mt @ 0.74% Cu, 54 g/t Ag.

Comment (Economic Factors): THE TROY MINE PUMPS ABOUT $22 M INTO THE LOCAL ECONOMY ASARCO ANNOUNCED THAT THE TROY MINE CONTRIBUTES $8M TO ASARCOS PRETAX EARNING ASSUMING A COPPER PRICE OF $.72 /LB $10/OZ SILVER AND A DEDUCTION OF 25 PCT. ROYALTY AFTER DEDUCTING EXPENSES DUE KENNECOTT MINERALS

Comment (Deposit): ORE MINERALS OCCUR AS DISSEMINATIONS, CLOTS, BEDDING AND SHEAR PLANE CONCENTRATIONS, AND FRACTURE FILLINGS (BURNSIDE AND THOMPSON, 1985).

Comment (Geology): BULL LAKE FAULT. THE EAST FAULT AT TROY FORMS THE EAST BOUNDARY OF THE ORE DEPOSIT IN MOST PLACES (BURNSIDE AND THOMPSON, 1985). THE MINERAL ZONATION BOUNDARIES SUBPARALLEL THE FAULT (BALLA, HAYES ET AL., 1983); THE CU/PB AND ZN RATIO DECREASES AWAY FROM THE FAULT (LANGE, 1983). THE INFERRED MAJOR DIRECTION OF ORE SOLUTION MOVEMENT WAS TO THE NORTHWEST, PARALLEL TO THE FAULT. THE EAST FAULT ALSO CONTAINS QUARTZ VEINS, VEINLETS, AND STOCKWORKS OF BORNITE, CHALCOPYRITE, AND OTHER SULFIDES THAT ARE VERY HIGH-GRADE, BUT RETAIN THE RELATIVE AG/CU PROPORTIONS OF THE DISSEMINATED ZONES THEY CUT (BALLA, HAYES, ET AL., 1983)

Comment (Geology): DIMENSIONS PERTAIN TO M1C3 (MINE PLAN RESOURCE). DEPOSIT IS STRATABOUND AND PROBABLY FORMED BY EPIGENETIC PROCESSES.

Comment (Deposit): ACCORDING TO ASARCO, THE SPAR LAKE DEPOSIT IS ABOUT 7,400 FEET LONG, 1800 FEET WIDE, AND AVERAGES ABOUT 60 FEET IN THICKNESS- AVERAGE GRADEIS 0.74% Cu AND 1.54 TOZ Ag/ ST

Comment (Reserve-Resource): ASARCO 1978 10K. EXPECTED POTENTIAL 4.2 MILLION OZ SILVER PER YEAR FOR ABOUT 16 YEARS. DEPOSIT REPORT AUTHOR: SCHUMACHER. MINE SHUT DOWN IN APRIL 1993. RESERVES FROM PAY DIRT FEBRUARY 1993, P. 8A.

Comment (Reserve-Resource): M1C3=MINE PLAN RESOURCE RESOURCES ARE NONCUMULATIVE

Comment (Geology): BORNITE CHALCOCITE AND CHALCOPYRITE OCCUR IN A RATIO OF 7:3:1

Comment (Economic Factors): JACK BINGHAM STATED THAT THE AVERAGE MILL FEED IS AVERAGING ABOUT 6 PCT HIGHER THAN EXPECTED. CURRENTLY THE CONCENTRATE IS SHIPPED TO ASARCOS TACOMA WA SMELTER AND ON TO THEIR AMARILLO TX REFINERY.

Comment (Workings): NO MAJOR ENVIRONMENTAL PROBLEMS ENCOUNTERED.

Comment (Economic Factors): INCLINE ADIT SLOPES UPWARD FROM MILLSITE TO OREBODY.

Comment (Reserve-Resource): ASARCO, INC., 1988 AR, P15.

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References

Reference (Deposit): EARHART, R.L., M.D. KLEINKOPF, D.M. WILSON, D.J. GRIMES, AND N.T. ZILKA. MINERAL RESOURCES OF SCOTCHMAN PEAK WILDERNESS STUDY AREA. U.S. GEOL. SURV. OFR 76-706, 1976, 136 PP.

Reference (Deposit): MINING JOURNAL. ASARCO'S TROY MINE. OCT. 1981, PP. 2-4.

Reference (Deposit): WESTERN MINE ENGINEERING MING COST SERVICE. SPOKANE, WA 1983

Reference (Deposit): TROY PROJECT OPERATING PLAN. SUBMITTED TO U.S. FOREST SERVICE, MAY 14, 1976.

Reference (Deposit): STRAAM ENGINEERS, INC. CAPITAL AND OPERATING COSTS ESTIMATING SYSTEM HANDBOOK. BUMINES CONTRACT NO. J0255026, 1979, 374 PP.

Reference (Deposit): STEARNS-ROGER, INC. ENVIRONMENTAL BASELINE INFORMATION OF THE MOUNT VERNON REGION--MONTANA. PREPARED FOR ASARCO, JAN. 31, 1975, UNPUBL.

Reference (Deposit): ASARCO'S NEW TROY MINE. PAPER PRESENTED AT THE 89TH ANNU.NORTHWEST MINING CONVENTION, SPOKANE, WA, DEC.1-3, 1983.

Reference (Deposit): BINGHAM, J. P., MANAGER OF ASARCO'S TROY MINE. PERSONAL COMMUNICATION, 1984.

Reference (Deposit): BEAR CREEK MINING COMPANY. PRIVATE COMPANY REPORTS. UNPUBL.

Reference (Deposit): BALLA , J. C. ASARCO MANAGER NORTHWESTERN EXPLORATION DIVISION. PERSONAL COMMUNICATION, 1984.

Reference (Deposit): PAY DIRT MAGAZINE. ASARCO WORKING TO CLEAN UP TAILING TAILINGS PROBLEM AT TROY OPERATION. BIG SKY EDITION, JUNE, 1983, P. 23A.

Reference (Deposit): MONTANA DEPARTMENT OF REVENUE. REVENUE RECORDS. 1982, 1983.

Reference (Deposit): SKILLINGS' MINING REVIEW. ASARCO'S INCORPORATED NEW TROY SILVER-COPPER MINE. NOV. 20, 1982.

Reference (Deposit): DILLARD, G. TROY OPERATION MAKES ASARCO NATION'S LEADING SILVER PRODUCER, PAY DIRT BIG SKY EDITION, DEC. 1982. PP 5-7.

Reference (Deposit): DAYTON, S. H. ASARCO'S TROY MINE. ENG. AND MIN. J., FEB 1983, V. 184, NO. 9, PP. 40-46.

Reference (Deposit): COST REFERENCE GUIDE FOR CONSTRUCTION EQUIPMENT. EQUIPMENT GUIDE BOOK COMPANY, PALO ALTO, CA, 1983.

Reference (Deposit): 1995 ASARCO'S 1995 10K, P. A21.

Reference (Deposit): ASARCO INC. 1995 ANNUAL REPORT, P.11.

Reference (Deposit): ASARCO INC., 1994 10K, P.A18, A21.

Reference (Deposit): MONT. BUREAU OF MINES AND GEOL. BULLETIN 129, 1991,

Reference (Deposit): WHITE, T. ASARCO'S TACOMA SMELTER. PERSONAL COMMUNICATION, 1984.

Reference (Reserve-Resource): Revett Minerals Inc., 2009, Troy Mine: http://www.revettminerals.com/documents/Revett_Fact_Sheet_3.26.09.pdf, accessed July 23, 2009.
URL: http://www.revettminerals.com/documents/Revett_Fact_Sheet_3.26.09.pdf

Reference (General): Reipas, Ken, and Couture, Jean-Francois, 2005, Independent Technical Report on the Troy Cu-Ag Project, Montana, U.S.A. for Revett Silver Company: SRK Consulting (CANADA) INC., Toronto, Ontario, SRK project Number: 3UR006.02, 223 p. [accessed January 5, 2010, at http://www.revettminerals.com/revOpTroyReports.php].
URL: http://www.revettminerals.com/revOpTroyReports.php

Reference (Reserve-Resource): Boleneus, D.E., Appelgate, L.M., Stewart, J.H., and Zientek, M.L., 2005, Stratabound Copper-Silver Deposits of the Mesoproterozoic Revett Formation, Montana and Idaho: U.S. Geological Survey Scientific Investigations Report 2005?5231, 66 p.

Reference (Deposit): GIBSON, R. GEOLOGY AND ORE DEPOSITS OF THE LIBBY QUADRANGLE, MONTANA. U.S. GEOL. SURV. BULL. 956, 1948, 131 PP.

Reference (Geology): Hayes T S, Einaudi M T 1986 - Genesis of the Spar Lake strata-bound Copper-Silver deposit, Montana: Part I. Controls inherited from sedimentation and preore diagenesis: in Econ. Geol. v81 pp 1899-1931

Reference (Deposit): JAYNE, D. A NORTHWEST METALS CONFERENCE-SPONSORED TOUR OF THE TROY MINE. PERSONAL NOTES, APR. 28, 1982.

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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.