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  3. Mineral Resource Data System (MRDS)

Tongass

Prospect in Alaska, United States with commodity Gold
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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. Mineral occurrence model information
  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 10001574
MRDS ID A012325
Record type Site
Current site name Tongass

Geographic coordinates

Geographic coordinates: -131.81067, 55.40863 (WGS84)
Relative position The Tongass prospect is at tidewater on northeast Gravina Island, about 0.3 mile southwest of Rock Point. The site is in section 36, T. 74 S., R. 89 E., of the Copper River Meridian. It corresponds to loc. 56 in Elliott and others (1978). The location is accurate within 0.1 mile.

Site location context

Political divisions (FIPS codes)

Ketchikan Gateway(Borough)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Ketchikan B-6(quadrangle 1:63,360 scale)

Ketchikan SW(quadrangle 1:100,000 scale)

Ketchikan(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Ketchikan(hydrologic unit)

Southern Southeast Alaska(hydrologic accounting unit)

Southeast Alaska(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary

Materials information

Materials Type of material
Gold Ore
Pyrite Ore
Quartz Gangue

Mineral occurrence model information

Model code 273
USGS model code 36a
Deposit model name Low-sulfide Au-quartz vein
Mark3 model number 27

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Metasedimentary Rock > Slate

Nearby scientific data

(1) -131.81067, 55.40863
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = The country rocks on northern Gravina Island are chiefly Upper Jurassic to mid-Cretaceous andesitic and basaltic volcanic rocks that gradationally intertongue with flyschlike sedimentary rocks. The rocks are intruded by at least one pluglike body of Tertiary gabbro (Berg, 1973; Berg and others, 1988). The bedded rocks were regionally metamorphosed to low-greenschist grade in Late Cretaceous time, and subsequently contact metamorphosed to hornblende hornfels near the contact of the Tertiary gabbro. The country rocks are cut by a high-angle fault along Tongass Narrows that displays about 4 miles of right-lateral offset.? the deposit is in Jurassic or Cretaceous slate and phyllite and consists of a reportedly auriferous, pyrite-bearing quartz fissure vein about one foot thick (Brooks, 1902, p. 61). The vein strikes NE and dips steeply NW, at an acute angle to the layering in the slate and phyllite.
  • Age = Late Cretaceous or younger.

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Mining district

District name Ketchikan

Reference information

Bibliographic references

Comments on the references

  • Primary Reference = Brooks, 1902; Berg, 1973

General comments

Subject category Comment text
Deposit Model Name = Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)

Reporter information

Type Date Name Affiliation Comment
Reporter 01-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.