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  3. Mineral Resource Data System (MRDS)

Unnamed (Johns Hopkins Inlet)

Occurrence in Alaska, United States with commodities Copper, Silver, Gold, Molybdenum, Tin, Tungsten
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Host and associated rocks
  9. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10002242
MRDS ID A013144
Record type Site
Current site name Unnamed (Johns Hopkins Inlet)
Related records 10136917

Geographic coordinates

Geographic coordinates: -137.01351, 58.89555 (WGS84)
Relative position The occurrence is at an elevation of about 850 feet on the east side of Johns Hopkins Inlet on a north-facing point where the inlet turns to the southwest. The location is approximately 0.25 mile south of the common corner of sections 23, 24, 25, and 26, T. 34 S., R. 50 E., of the Copper River Meridian. The location is accurate within 250 feet. It is approximately location number 30 of Kimball and others (1978, fig. C38, p. C172); it is near number 74 of MacKevett and others (1971).

Site location context

Political divisions (FIPS codes)

Hoonah-Angoon(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Mount Fairweather D-4(quadrangle 1:63,360 scale)

Mount Fairweather NE(quadrangle 1:100,000 scale)

Mount Fairweather(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Glacier Bay(hydrologic unit)

Northern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Glacier Bay National Park(National Park)

National Park NPS(Type of land area)

NPS(Federal land areas administered by NPS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Silver Secondary
Gold Secondary
Molybdenum Secondary
Tin Critical Secondary
Tungsten Critical Secondary

Materials information

Materials Type of material
Cassiterite Ore
Chalcopyrite Ore
Molybdenite Ore
Pyrrhotite Ore

Alteration

  • (Local) Widespread sulfidation of intrusive and volcanic rocks, now reflected in iron-stained rocks.

Host and associated rocks

  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic)
    Stratigraphic age (youngest) Late Cretaceous
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic)

Nearby scientific data

(1) -137.01351, 58.89555
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Interlayered volcanic and sedimentary rocks of Permian age occur west of an approximately concordant granitic intrusion of Cretaceous age that extends northerly across Johns Hopkins Inlet (Brew and others, 1978, plate 1A). Kimball and others (1978) note intermixed diorite and mixed sedimentary and volcanic rocks in the area, and, at this occurrence, there is a conspicuous iron-stained zone about 0.25 mile wide. Grab samples (rock in place) contained from 10 to more than 30 ppm molybdenum (Kimball and others, 1978, fig. C38, p. C147-149). A selected sample (7S044) from a thin (0.2 foot) lens of pyrrhotite in sulfidized volcanics contained 1300 ppm copper, 30 ppm molybdenum, 1.5 ppm silver, and >0.05 ppm gold. A float sample of hornfels (Kimball and others, 1978, location 30, p. C172) from the same area contained 4100 ppm copper, 7 ppm silver, 0.15 ppm gold, 700 ppm tin and 793 ppm tungsten. The sample contained visible chalcopyrite and pyrrhotite.
  • Age = Possibly Cretaceous, based on age of granitic plutons in the area.

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 = Surface occurrence only. A Bureau of Mines select sample (7SO44) of a pyrrhotite lens contained 1,300 ppm copper. 30 ppm molybdenite, 1.5 ppm silver and greater than 0.05 ppm gold; also reported from the same area is a float sample of hornfels that contained 0.41 percent copper, 250 ppm zinc, 7 ppm silver, 700 ppm tin and 793 ppm tungsten (Kimball and others, 1978, p. C147, C172). MacKevett and others (1971, table 9, no. 74) found 150 ppm copper and 30 ppm molybdenum in a grab sample of an iron-stained granitic intrusion in the area.

Reference information

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.

Comments on the references

  • Primary Reference = Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Skarn, massive sulfide type.
Deposit Other Comments = Moderately large occurrence of iron-stained granitic pluton and hornfelsed volcanic and sedimentary rocks, not adequately prospected. The area is Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 09-APR-99 Hawley, C.C. Hawley Resource Group

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.