Unnamed (Johns Hopkins Inlet)

Occurrence in Alaska, United States with commodities Copper, Silver, Gold, Cobalt, Molybdenum

Geologic information

Identification information

Deposit ID 10002240
MRDS ID A013142
Record type Site
Current site name Unnamed (Johns Hopkins Inlet)
Related records 10258053

Geographic coordinates

Geographic coordinates: -136.99518, 58.89972 (WGS84)
Relative position The occurrence is on a north-facing point into Johns Hopkins Inlet, almost due south of Orange Point; it is in section 24, T. 34 S., R. 50 E., of the Copper River Meridian. The location is accurate to within 0.25 mile. The location is approximately the same as number 65 of MacKevett and others (1971), number 15 of Cobb (1972) and number 29 of Kimball and others (1978).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Silver Secondary
Gold Secondary
Cobalt Secondary
Molybdenum Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Chrysocolla Ore
Limonite Ore
Malachite Ore
Molybdenite Ore

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Hornfels

Nearby scientific data

(1) -136.99518, 58.89972

Comments on the geologic information

  • Geologic Description = Argillite, phyllite, and slate of Permian and Permian (?) age are cut by a small foliated granite pluton of Cretaceous age (Brew and others, 1978, plate IA). Kimball and others (1978, p.C149, fig. C38 ) reported volcanic rock, chert, and sulfides. MacKevett and others (1971, table 9, p. 52) reported a 100- to 200-foot wide altered zone in granitic rocks which extended several hundred feet on strike: fracture surfaces were stained with malachite, chrysocolla, and limonite. ? A grab sample collected by the U.S. Geological Survey contained 1500 ppm copper and 30 ppm molybdenum. Float samples collected by the U.S. Bureau of Mines (Kimball and others, 1978) contained as much as 4,600 ppm copper, 7 ppm silver, and 0.05 ppm gold. A rock sample collected by the Bureau contained more than 2000 ppm molybdenum and 610 ppm copper.
  • Age = Cretaceous .

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau

Comments on the workings information

  • Workings / Exploration = There are no mine workings. A grab sample representative of a shear zone in granitic rock contained 1500 ppm copper and 30 ppm molybdenum (MacKevett and others, 1978, sample 65, table 9). The U.S. Bureau of Mines (Kimball and others, 1978) collected float samples at about 150 feet elevation, in an area underlain by hornfels, that contained 4600 ppm copper, 300 ppm cobalt, 7 ppm silver, and 0.05 gold (p. C-172). A selected sample of a veinlet in hornfels at about 300 feet elevation contained greater then 2000 ppm molybdenum and 610 ppm copper.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013142
USGS Alaska Resource Data File ARDF MF039

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

    Cobb, E. H., 1981, Summaries of data and lists of references to metallic and selected non-metallic mineral occurrences in the Mt. Fairweather quadrangle, Alaska, Supplement to Open-file Report 78-316: U. S. Geological Survey Open-File Report 81-249B, 15 p.

  • Deposit

    Cobb, E.H., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Mt. Fairweather quadrangle, Alaska; Supplement to Open-file Report 78-316; Part A, Summaries of data to January 1, 1980: U.S. Geological Survey Open-File Report 81-249-A, 20 p.

  • 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 = Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Mineralized shear zone; possible volcanogenic mineralization.
Deposit Other Comments = the area has numerous iron-stained areas, contact zones, and has widespread weak geochemical anomalies in copper and molybdenum. Favorable area for contact or intrusive-related shear zone-type deposits. The area is in Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-APR-99 Hawley, C.C. Hawley Resource Group