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Unnamed (on Threesome Mountain)

Prospect in Alaska, United States with commodities Molybdenum, Tungsten, Silver, Copper
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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 10002278
MRDS ID A013182
Record type Site
Current site name Unnamed (on Threesome Mountain)
Related records 10112440

Geographic coordinates

Geographic coordinates: -136.56792, 58.53166 (WGS84)
Relative position The deposit is on the east flank of Threesome Mountain, about 1.5 miles northeast of the head of Abyss Lake. Elevation of the deposit ranges from about 2000 to 2800 feet. The deposit is about one-half mile long, elongated east-west. The coordinate location is the approximate mid-point of the deposit, and is accurate to about 0.1 mile.

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 C-2(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
Molybdenum Primary
Tungsten Critical Primary
Silver Secondary
Copper Secondary

Comments on the commodity information

  • Ore Material = silver mineral

Materials information

Materials Type of material
Chalcopyrite Ore
Molybdenite Ore
Scheelite Ore
Quartz Gangue

Alteration

  • (Local) Local iron staining.

Mineral occurrence model information

Model code 42
USGS model code 14a
Deposit model name W skarn
Model code 80
USGS model code 21b
Deposit model name Porphyry Mo, low-F

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 Plutonic Rock > Mafic Intrusive Rock > Diorite

Nearby scientific data

(1) g
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = This molybdenum-tungsten prospect is in a terrane composed mainly of Paleozic sedimentary rocks. The prospect is east of a major fault that separates the Paleozoic strata from granitic rock of Mesozoic age. The fault is concealed by Brady Glacier and is inferred to control the course of Taylor Bay to the south (Brew and others, 1978). The deposit is of porphyry-type. Molybdenite and scheelite, with minor chalcopyrite, occur in the roof-zone of a Tertiary granodiorite stock that intrudes volcanic and sedimentary rocks (limestone) of Devonian age. The molybdenite and scheelite occur in quartz veins and as fracture coatings on joints in the intrusion. Molybdenum-bearing vein density measured by the U.S. Bureau of Mines (Kimball and others, 1978, p. C-253-C256) was about eight veins per 100 feet. The maximum observed vein thickness was 0.2 foot, with an average of about 0.08 foot. Mineralized veins and fractures strike east-northeast and dip from 25 to 76 degrees northwest. Selected vein samples contained as much as 2000 ppm molybdenum, 4917 ppm tungsten, 7 ppm silver, and 330 ppm copper. Iron-stained hornfels near the granitic stock contains as much as 200 ppm copper and 50 ppm tungsten. The deposit has been drilled, and is a resource on the order of 0.0X percent equivalent molybdenum.? Richer tactite deposits could occur in nearby contact zones between the stock and the limestone.
  • Age = Tertiary.

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 workings information

  • Workings / Exploration = The deposit was discovered by Alvenco, Inc. in 1968, who staked 24 claims to cover it. Alvenco drilled three diamond drill holes to evaluate the deposit. The grades were in the low 0.0X range molybdenum equivalent . Selected samples collected by the Bureau of Mines contained as much as 2000 ppm molybdenum and more than 4000 ppm tungsten (Kimball and others, 1968).

Reference information

Bibliographic references

  • 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 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., 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.

Comments on the references

  • Primary Reference = Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Porphyry molybdenum-tungsten deposit, similar to W skarn and porphyry Mo of Cox and Singer (1986; model 14a and 21b). Associated tactite. Porphyry deposit is mainly mineralized fracture surface type.
Deposit Model Number = 14a, 21b
Deposit Other Comments = the deposit is in Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 14-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.