Northern Copper Company

The Northern Copper Company is a copper and zinc 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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Site Name

Primary: Northern Copper Company
Secondary: Tower Arm Copper
Secondary: Portage Bay Copper Company

Commodity

Primary: Copper
Primary: Zinc

Location

State: Alaska
District: Kupreanof

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

Not available

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Unclear.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Pyrrhotite
Ore: Magnetite
Ore: Chalcopyrite
Ore: Sphalerite

Comments

Comment (Production): Production Notes = None

Comment (Geology): Age = Unknown.

Comment (Reserve-Resource): Reserves = None

Comment (Workings): Workings / Exploration = Prospect active from 1900 to 1921 with several hundred feet of underground workings, and considerable trenching; a road was built part way to the prospect from the head of Duncan Canal. The prospect was restaked in 1978 and was drilled in 1978 and 1979; the results of this work have not been made public but the drill results were not encouraging (oral communication, AMOCO Minerals, 1980). There has apparently been no further surface work on the property through the summer of 1996.

Comment (Deposit): Model Name = An enigma, possibly a skarn (but probably not a volcanogenic massive sulfide deposit).

Comment (Exploration): Status = Probably inactive

Comment (Geology): Geologic Description = Mineralization occurs as pods and irregular masses of magnetite, sphalerite, pyrrhotite, and chalcopyrite in a locally garnet-bearing, equigranular, pyroxene-rich porphyritic greenstone associated with minor coarse-grained marble. The older literature identifies the host rock as 'pyroxene granulite', but the lithology of the host rock and the origin of the deposit are enigmatic; the mineralized greenstone appears skarn-like locally. The sulfides are either interstitial to pyroxene in the greenstone or replace massive fine-grained greenstone. Drilling in the late 1970's by AMOCO Minerals (oral communication, 1981) indicate that the greenstone is underlain at shallow depth by green siliceous phyllite, which is in turn underlain by black carbonaceous argillite. Sulfides frequently occur in bands parallel to the compositional layering of the greenstone. Analyses of selected sulfide-bearing samples show major Cu and Zn commensurate with the visible mineralogy, less than 0.05 ppm Au and up to 5 ppm Ag. (Description synthesized from Wright and Wright, 1908, p. 41-142, Buddington, 1923, p. 70-72; Roehm, 1945 [DGGS IR 195-37]; Twenhofel and others, 1949, p. 37-38; personal communications from AMOCO Minerals who drilled the property in the late 1970's; and field work by the reporters that was summarized in Grybeck, Karl, and Berg, 1984.) ? Brew and others (1984) mapped the country rocks in the vicinity as part of a regionally extensive, undifferentiated Mesozoic volcanic unit.

References

Reference (Deposit): Buddington, A.F., 1923, Mineral deposits of the Wrangell district; U.S. Geological Survey Bulletin 739, p. 51-75.

Reference (Deposit): Wright, F.E., and Wright, C.W., 1908, The Ketchikan and Wrangell mining districts, Alaska: U.S. Geological Survey Bulletin 347, 210 p.

Reference (Deposit): Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Petersburg quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-870, 53 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Petersburg quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-415, 1 sheet, scale 1:250,000.

Reference (Deposit): Brew, D. A., Ovenshine, A. T., Karl, S. M., and Hunt, S. J., 1984, Preliminary reconnaissance geologic map of the Petersburg and parts of the Port Alexander and Sumdum 1:250,000 quadrangles, southeastern Alaska: U.S. Geological Survey Open-File Report 84-405, 43 p., 2 sheets, scale 1:250,000.

Reference (Deposit): Twenhofel, W.S., Reed, J. C., and Gates, G.O., 1949, Some mineral investigations in southeastern Alaska: U.S. Geological Survey Bulletin 963-A, p. 1-45.

Reference (Deposit): Roehm, J.C., 1945, Preliminary report of investigations in the Juneau and Petersburg precincts and itinerary of J. C. Roehm: Alaska Territorial Department of Mines Itinerary Report 195-38, 10 p.

Reference (Deposit): Roehm, J.C., 1945, Preliminary report of investigations and itinerary of J. C. Roehm in the Wrangell and Petersburg precincts, Alaska: Teritory of Alaska, Department of Mines Itinerary Report 195-37, 13 p.

Reference (Deposit): Grybeck, D.J., Berg, H.C., and Karl, S.M., 1984, Map and description of the mineral deposits in the Petersburg and eastern Port Alexander quadrangles: U.S. Geological Survey Open-File Report 84-837, 86 p., 1 sheet, scale 1:250,000.

Reference (Deposit): Cobb, E. H., 1972, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Petersburg Quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-870, 53 p.

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