Nunatak (south of Snowcap Mountain)

Occurrence in Alaska, United States with commodities Silver, Gold, Copper, Cobalt, Nickel, Lead, Zinc

Geologic information

Identification information

Deposit ID 10307759
Record type Site
Current site name Nunatak (south of Snowcap Mountain)

Geographic coordinates

Geographic coordinates: -153.62525, 61.40626 (WGS84)
Relative position This occurrence is at an elevation of 5,500 feet on the south end of a small nunatak, 3.25 miles south of Snowcap Mountain. It is in the NW1/4 section 8, T 15 N, R 24 W, of the Seward Meridian. This location is accurate; other vein occurrences are within a quarter of a mile of this location (Gamble and others, 1989).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Gold Primary
Copper Primary
Cobalt Secondary
Nickel Secondary
Lead Secondary
Zinc Secondary

Materials information

Materials Type of material
Alloclasite Ore
Arsenopyrite Ore
Chalcopyrite Ore
Erythrite Ore
Galena Ore
Glaucodot Ore
Magnetite Ore
Pyrite Ore
Pyrrhotite Ore
Sphalerite Ore
Amphibole Gangue
Apatite Gangue
Chlorite Gangue
Epidote Gangue
Plagioclase Gangue
Quartz Gangue
Clinopyroxene Gangue

Alteration

  • (Local) The sulfide-bearing veins may be variably altered and replaced mafic dikes.

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Nearby scientific data

(1) -153.62525, 61.40626

Comments on the geologic information

  • Geologic Description = Barren quartz veins, quartz-amphibole veins, and sulfide-bearing veins occupy east-west trending, sub-vertical fractures in biotite-hornblende monzodiorite to quartz monzodiorite in this area (Gamble and others, 1989). Two sulfide-bearing veins at an elevation of 5,500 feet on the south end of a small nunatak are about 1 to 2 feet wide and contain 5 to 70 percent chalcopyrite, arsenopyrite, and magnetite, and lesser amounts of galena, sphalerite, pyrite, and pyrrhotite. Erythite (cobalt bloom) is locally present and gangue minerals in the sulfide-bearing veins include amphibole, apatite, clinopyroxene, chlorite, epidote, quartz, and plagioclase. Composite chip samples of these veins contain as much as 1.5 ppm gold, 150 ppm silver, and greater than 20,000 ppm copper, 2,000 ppm arsenic, and 2,000 ppm copper. Apatite is locally abundant in the veins, and some samples contain as much as 1 percent phosphorus. Other sulfide-rich samples from the area contain up to 12 ppm gold, 700 ppm silver, and 640 ppm bismuth, and greater than 20,000 ppm copper, 2,000 ppm arsenic, and 2,000 ppm cobalt. A sample that contains greater than 20,000 ppm arsenic, 5,000 ppm cobalt, and 10,000 ppm nickel and only 7 percent iron may be glaucodot- or alloclasite-bearing (Gamble and others, 1989). The gangue mineralogy of the sulfide-bearing veins may indicate that they are in part mineralized mafic dikes.
  • Age = Cretaceous or Tertiary the veins crosscut granitic rocks that may be Late Cretaceous or Tertiary parts of the Alaska-Aleutian Range batholith.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Reconnaissance sampling has been done in this area (Gamble and others, 1989).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF LH025

Bibliographic references

  • Deposit

    Gamble, B.M., Bailey, E. A., and Reed, B. L., 1989, Gold occurrences near Snowcap Mountain, Lime Hills B-2 quadrangle, Alaska: U.S. Geological Survey Open-File Report 89-0646, 8 p.

Comments on the references

  • Primary Reference = Gamble and others, 1989

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins? (Cox and Singer, 1986, model 22c)

Reporter information

Type Date Name Affiliation Comment
Reporter 10-JUN-01 Travis L. Hudson Applied Geology
Reporter 10-JUN-01 Madelyn A. Millholland Millholland & Associates