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Unnamed (northeast side of Willoughby Island)

Prospect in Alaska, United States with commodities Copper, Arsenic, Cobalt
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Geologic information

Identification information

Deposit ID 10002277
MRDS ID A013181
Record type Site
Current site name Unnamed (northeast side of Willoughby Island)
Related records 10233543

Geographic coordinates

Geographic coordinates: -136.13208, 58.59973 (WGS84)
Relative position The deposit is reported to be on the northeast side of Willoughby Island at an elevation of 450 feet. It is assumed to be about 0.5 mile southwest of Johnson Cove. Accuracy is uncertain. The site is about the same as locality 49 in Cobb (1972) and locality 95 in Kimball and others (1978). The deposit was not found by the U.S. Geological Survey in 1966 (MacKevett and others, 1971).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Arsenic Secondary
Cobalt Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrite Ore
Lollingite Ore
Calcite Gangue

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone

Nearby scientific data

(1) -136.13208, 58.59973
ListMap

Comments on the geologic information

  • 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.
  • Age = Late Cretaceous or younger.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau

Comments on the workings information

  • 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.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013181
USGS Alaska Resource Data File ARDF MF069

Bibliographic references

  • 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.

  • 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.

  • 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.

  • Deposit

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

  • 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.

Comments on the references

  • Primary Reference = Reed, 1938

General comments

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

Reporter information

Type Date Name Affiliation Comment
Reporter 14-APR-99 Hawley, C.C. Hawley Resource Group