Unnamed (northeast side of Willoughby Island)

The Unnamed (northeast side of Willoughby Island) is a 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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Site Name

Primary: Unnamed (northeast side of Willoughby Island)

Commodity

Primary: Copper
Secondary: Cobalt
Secondary: Arsenic

Location

State: Alaska
District: Juneau

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

Not available

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Ore: Pyrite
Ore: Lollingite
Gangue: Calcite

Comments

Comment (Exploration): Status = Inactive

Comment (Geology): Age = Late Cretaceous or younger.

Comment (Deposit): Other Comments = the deposit is in marble of Devonian and Silurian age; mineralization followed emplacement of mafic dikes of probable Late Cretaceous or Tertiary age. ? the site is in Glacier Bay National Park and Preserve.

Comment (Reference): Primary Reference = Reed, 1938

Comment (Workings): Workings / Exploration = The deposit has not been found since Reed's visit in the 1930s (Reed, 1938). Workings are unknown, but there probably were shallow pits and trenches on the eight claims staked on the deposit before 1902.

Comment (Deposit): Model Name = Massive sulfide replacement in marble. Distal deposit related to subjacent intrusive; deposits formed after late emplacement of mafic dikes.

Comment (Geology): Geologic Description = The northeastern part of Willoughby Island is underlain by massive and bedded limestone of Devonian and Silurian age, part of a major reefoid mass (Brew and others, 1978). Locally the marble is cut by mafic dikes of Late Cretaceous or Tertiary age. At this prospect, pyrite, loellingite (?) and chalcopyrite form massive replacement layers or lenses in marble. One such massive sulfide deposit was described as 5-feet-thick and traceable on strike for 15 feet (Reed, 1938). At least three other similar occurrences were reported nearby by Reed.

References

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Mount Fairweather quadrangle, AK: U.S. Geological Survey Miscellaneous Field Study Map MF-436, 1 sheet, scale 1:250,000.

Reference (Deposit): Reed, J.C., 1938, Some mineral deposits of Glacier Bay and vicinity, Alaska: Economic Geology, v. 33, p. 52-80.

Reference (Deposit): Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p.

Reference (Deposit): Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources, in Brew, D. A., and others, Mineral resources of the Glacier Bay National Monument wilderness study area, Alaska: U.S. Geological Survey Open-File Report 78-494, p. C1-C375.

Reference (Deposit): MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.

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