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Black Jack

Prospect in Alaska, United States with commodity Uranium
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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 10094042
MRDS ID A012369
Record type Site
Current site name Black Jack
Alternate or previous names Black Jack No. 7, Black Jacks
Related records 10112908

Geographic coordinates

Geographic coordinates: -131.74482, 55.15085 (WGS84)
Relative position The Black Jack prospect is at an elevation of less than 100 feet, near the base of the peninsula that forms the east side of Dall Bay The prospect is in section 32, T. 77 S., R. 91 E., of the Copper River Meridian, about 0.1 mile northeast of the southeast head of the bay, and about 500 feet from tidewater. The site corresponds to loc. 126 in Elliott and others (1978), and to loc. 315 in Maas and others (1995). The location is accurate within 0.1 mile. ? Also see Additional comments.

Site location context

Political divisions (FIPS codes)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan A-6 NE(quadrangle 1:24,000 scale)

Ketchikan SW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Federal lands

Tongass National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Uranium Primary

Materials information

Materials Type of material
Pitchblende Ore

Alteration

  • (Local) Probable local hydrothermal alteration (disseminated hematite) of trondhjemite or other country rock. Reported serpentinization of basalt or gabbro dike hostrock.

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Mafic Intrusive Rock > Gabbro

Nearby scientific data

(1) -131.74482, 55.15085
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The country rocks in the area of this prospect consist of an assemblage of undivided Silurian or Ordovician metamorphosed bedded and intrusive rocks that are intruded by stocks and dikes of Silurian trondhjemite (Berg, 1973; Berg and others, 1988), the rocks are cut by a complex system of high-angle faults that mainly strike NE and NW. Locally, they also are permeated by finely disseminated hydrothermal hematite, giving them (especially the trondhjemite) a pink or red hue commonly mistaken for potassium feldspar. ? the deposit consists of a thin, discontinuous seam, or seams, of a black, radioactive mineral, possibly pitchblende, in a dike of 'serpentinized' basalt or gabbro that may be in fault contact with metamorphic country rocks (Elliott and others, p. 13). The radioactive mineral apparently occurs on the surfaces of small faults. A 2.5-foot-thick layer (dike?) of 'pink feldspar' that may be hydrothermally altered trondhjemite, forms the hanging wall of the fault plane(s) on which the radioactive material occurs. A site examination and tests with a Geiger counter in 1956 showed only traces of radioactive material (J.A. Williams, unpublished site examination report, Alaska Territorial Department of Mines, 1956). Several samples collected at that time contained up to 0.07% U, and one sample contained several percent equivalent uranium. Workings in 1956 consisted of several small pits. ? According to Maas and others (1995, p. 227, 229), a 1970 reconnnaissance of the prospect indicates that the radioactive material occurs in albite pods adjacent to small, serpentinized zones in basalt or gabbro. The highest radioactivity in the pods is associated with thin, black coatings on fractures in the feldspar.

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Mining district

District name Ketchikan

Comments on the workings information

  • Workings / Exploration = A site examination and tests with a Geiger counter in 1956 showed only traces of radioactive material (J.A. Williams, unpublished site examination report, Alaska Territorial Department of Mines, 1956). Several samples collected at that time contained up to 0.07% U, and one sample contained several percent equivalent uranium. Workings in 1956 consisted of several small pits.

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Elliott and others, 1978; Maas and others, 1995

General comments

Subject category Comment text
Deposit Model Name = Radioactive veins or coatings of undetermined origin, in basalt or gabbro.
Deposit Other Comments = At various times, this property has also been referred to as Black Jack No. 7, and Black Jacks (Cobb and Elliott, 1980, p. 17).

Reporter information

Type Date Name Affiliation Comment
Reporter 05-JUL-1999 H.C. Berg U.S. Geological Survey

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.