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Alaska Chief

Prospect in Alaska, United States with commodities Silver, Gold, Copper, Bismuth, Cobalt, Nickel, Zinc
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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. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

Geologic information

Identification information

Deposit ID 10002287
MRDS ID A013191
Record type Site
Current site name Alaska Chief

Geographic coordinates

Geographic coordinates: -136.10318, 58.44472 (WGS84)
Relative position The Alaska Chief prospect is on a steep northeast-facing sidehill at about 1150 ft elevation. The prospect is about 0.7 mile southwest of Ripple Cove and about 0.85 mile slightly north of east from Hill 2146. Its general location is 5 miles north of the mouth of Glacier Bay into Icy Straits on the west side of the bay. The prospect is accurately located by elevation, but its location could range within about 0.15 mile along the contour. It was formerly accessible by trail from Ripple Cove, but the trail is badly overgrown.

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 B-1(quadrangle 1:63,360 scale)

Juneau SW(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
Silver Primary
Gold Primary
Copper Primary
Bismuth Critical Secondary
Cobalt Critical Secondary
Nickel Critical Secondary
Zinc Critical Secondary

Materials information

Materials Type of material
Azurite Ore
Bornite Ore
Chalcopyrite Ore
Limonite Ore
Malachite Ore
Pyrite Ore
Pyrrhotite Ore
Sphalerite Ore
Calcite Gangue
Quartz Gangue

Alteration

  • (Local) Formation of contact-metasomatic calc-silicate minerals in limestone and contact zone of granitic intrusion; local oxidation of copper and iron minerals.

Mineral occurrence model information

Model code 59
USGS model code 18b
Deposit model name Skarn Cu
Mark3 model number 8

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Stratigraphic age (youngest) Pliocene
  • Host or associated Host
    Rock type Metamorphic Rock > Metasedimentary Rock > Marble

Nearby scientific data

(1) -136.10318, 58.44472
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Rocks exposed in the vicinity of the deposit are limestone and marble of Paleozoic age, and foliated granodiorite of probable Cretaceous age. About 0.1 mile west of the deposit, a lighter colored granitic rock of probable Tertiary age intrudes the granodiorite (MacKevett and others, 1971). Massive sulfides and tactite replace marble and hornfels in the contact zone of the granodiorite pluton. The major components of the tactite are grossularite-rich garnet, epidote and zoisite. The contact and relict bedding at the deposit strike about N 30 W and dip steeply to the southwest. Although the deposit is physically associated with the contact of foliated granodiorite of Cretaceous age, it is possible that the mineral deposit is genetically related to the younger intrusion and only physically controlled by the favorable older contact zone.? the deposit consists of a massive-sulfide body grading out into a disseminated deposit in contact altered country rock (Reed, 1938). The massive sulfide replacement body occurs under a 150- by 55-foot stripped area. At the surface, the massive sulfide body was oxidized to a limonitic gossan, possibly manganiferous. Azurite and malachite are locally abundant in the oxidized part of the deposit. The underlying sulfide-rich deposit contains bornite, chalcopyrite, pyrite, pyrrhotite and sphalerite.? Grab samples of ore stockpiled near old workings contained more than 10 percent copper. MacKevett and others (1971) reported as much as 0.232 ounce per ton gold, 4.4 ounces per ton silver, and 1.5 percent copper when they resampled the deposit in 1966.
  • Age = Late Cretaceous or younger.

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 reserve resource information

  • Reserves = Based on a surface dimension of 150 x 30 feet projected to a depth of 50 feet, and a tonnage factor of 8 cubic-feet / ton, MacKevett and others (1971, p. 48) propose an indicated reserve of about 28000 tons that would contain more than 1 percent copper, 2 ounces per ton silver, and 0.10 ounce per ton gold. This estimate, however, is probably too high because the adit driven below the deposit is in lower-grade ore. Kimball and others (1978, p. C353) concurred with the USGS's reserve estimate but it seems more realistic to call it inferred because the subsurface data are so scant.

Comments on the workings information

  • Workings / Exploration = The prospect was discovered before 1906 and was patented in 1924. It was explored by clearing vegetation off the outcrop and by an adit driven about 60 feet below the outcrop. Wright and Wright (1937, p. 221-222) reported the adit as 130 feet in length. Reed (1938, p. 37), and MacKevett and Cornwall (in MacKevett and others, 1971, p. 45-48, fig. 9) found an adit less than 40 feet long. It thus appears likely that the Wrights' footage measurement is in error or that the workings found by the Wrights are covered by surface debris.? MacKevett and others (1971) reported as much as 1.5 percent copper, 700 ppm zinc, 0.232 ounce per ton gold and 4.4 ounce per ton silver and geochemically anomalous sample values molybdenum, bismuth, nickel and cobalt. A grab sample from an old ore pile contained more than 10 percent copper. A soil sample collected below the stripped area contained 50 ppm each of silver and gold, 15,000 ppm copper, 300 ppm each of bismuth and cobalt, 500 ppm nickel and 1500 ppm zinc. The deposit has not been drilled.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = MacKevett and others, 1971

General comments

Subject category Comment text
Deposit Model Name = Copper skarn (Cox and Singer, 1986; model 18b). Contact metasomatic copper-gold deposit, massive sulfide and skarn replacement.
Deposit Other Comments = the deposit justifies further study and exploration because of its grade and possible size. It is in Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 22-JAN-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.