The Tarn is a gold and copper mine located in Alaska.
About the MRDS Data:
All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.
Mine Info
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Tarn MRDS details
Site Name
Primary: Tarn
Commodity
Primary: Gold
Primary: Copper
Secondary: Antimony
Secondary: Arsenic
Location
State: Alaska
District: McGrath
Land Status
Not available
Holdings
Not available
Workings
Not available
Ownership
Not available
Production
Not available
Deposit
Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:
Physiography
Not available
Mineral Deposit Model
Model Name: Porphyry Cu-Au
Orebody
Not available
Structure
Not available
Alterations
Alteration Type: L
Alteration Text: Biotite in hornfels; ankerite in intrusions.
Rocks
Not available
Analytical Data
Not available
Materials
Ore: Chalcopyrite
Ore: Arsenopyrite
Gangue: Tourmaline
Gangue: Quartz
Comments
Comment (Exploration): Status = Inactive
Comment (Workings): Workings / Exploration = Regional exploration work conducted by WGM Inc. in the late 1970s discovered the Tarn and related prospects in the Mystery Mountains (Andrews, 1978). From 1988 to 1990, American Copper and Nickel Company conducted regional exploration, which included a detailed airborne geophysical survey. ASA Inc. continued detailed exploration work from 1991 to 1997 (DiMarchi and others, 1997). No drilling has taken place on the property, and no assay data was found for this summary.
Comment (Deposit): Model Name = Porphyry Cu-Au (Cox and Singer, 1986; model no. 20c)
Comment (Deposit): Other Comments = See Copenhagen Hill (MD030), Frozen Creek (MD032), Pork Chop (MD031), and Mystery Mountains West (MD029) prospects.
Comment (Geology): Age = the Tarn prospect is inferred to be Late Cretaceous, based on isotopic ages of plutonic rocks in Mystery Mountains (Moll and others, 1981).
Comment (Reference): Primary Reference = DiMarchi and others, 1997
Comment (Geology): Geologic Description = The Tarn prospect is within the eastern part of a northeast trending belt of porphyry-like copper-gold prospects that strike for 7 miles (11 km) in the central Mystery Mountains. The Tarn prospect consists of hydrothermal breccias in monzonitic dikes and small stocks that contain chalcopyrite, pyrite, tourmaline, and minor to trace arsenopyrite. Malichite occurs in hairline fractures in intrusive rocks; alteration and mineralization is not well developed in country-rock hornfels. The Tarn prospect is inferred to be Late Cretaceous, based on isotopic ages of plutonic rocks in Mystery Mountains (Moll and others, 1981). No assay data was found for this summary.
References
Reference (Deposit): DiMarchi, J.J., and Frantz, P.S., 1997, Annual Report for 1997-Doyon Option Lands, Block 10: ASA Inc.-Montague Gold Joint Venture Report, Volume II: Unpublished report, 189 p. (Report held by Doyon, Limited, Fairbanks, Alaska.)
Reference (Deposit): Moll, E.J., Silberman, M.L., and Patton, W.W. Jr., 1981, Chemistry, mineralogy, and K-Ar ages of igneous and metamorphic rocks of the Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811C, 15 p., 2 sheets, scale 1:250,000.
Reference (Deposit): Andrews, Tom, 1978, Summary of Progress, Doyon Project, Mystery Mountains, (Block 10): Anchorage, Alaska, WGM Inc., 24 pages (Held by Doyon Ltd., as proprietary report 78-42).
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