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Rock Glacier

Occurrence in Alaska, United States with commodities Copper, Iron
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Geologic information

Identification information

Deposit ID 10307849
Record type Site
Current site name Rock Glacier

Geographic coordinates

Geographic coordinates: -154.13085, 62.35347 (WGS84)
Relative position The Rock Glacier occurrence is located in the headwall of an unnamed stream valley above an active rock glacier at an elevation of approximately 4,600 feet (1,402 m) in the SE1/4 sec. 8, T. 26 N., R. 26 W., of the Seward Meridian. The location is based on descriptions provided in Gilbert and others (1990). The reporter visited the site in 1984.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Iron Secondary

Comments on the commodity information

  • Gangue = Carbonate

Materials information

Materials Type of material
Malachite Ore
Pyrite Ore
Pyrrhotite Ore
Chlorite Gangue
Epidote Gangue
Quartz Gangue

Alteration

  • (Local) Propylitization.

Mineral occurrence model information

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

Nearby scientific data

(1) -154.13085, 62.35347
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Comments on the geologic information

  • Geologic Description = Pyrite-rich gossan zones were noted by Gilbert and others (1990) in a composite dike swarm, andesitic flows, and lappilli tuffs within the Windy Fork volcanic complex (Bundtzen, Harris, and Gilbert, 1997). Pyrite and pyrrhotite, which locally comprise up to 50 percent of the gossan-rich zones, are accompanied by carbonates, chlorite, epidote, and quartz. Individual gossan bodies are irregular in dimension, and reach maximum lengths of 40 meters Gangue mineralogy suggests formation by introduction of metasomatic fluids; i.e., skarns. Malachite staining was observed in some of the fractured hornfels in the gossan zones. No assay data is available for the Rock Glacier occurrence.
  • Age = K-Ar age of 37.9 Ma published by Gilbert and others (1990).

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 = No assay data is available for the Rock Glacier occurrence.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MG038

Bibliographic references

  • Deposit

    Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 pages, one sheet, scale 1:125,000.

  • Deposit

    Gilbert, W.G., Solie, D.N., Kline, J.T., and Dickey, D.B., 1990, Geologic map of the McGrath B-3 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 102, 2 sheets, scale 1:63,360.

Comments on the references

  • Primary Reference = Gilbert and others, 1990

General comments

Subject category Comment text
Deposit Model Name = Copper skarn(?) (Cox and Singer, 1986; model 18b).
Deposit Other Comments = Similar to Rat Fork-Headwall and Rat Fork-Base prospects (MG058; MG059) in McGrath B-2 quadrangle.

Reporter information

Type Date Name Affiliation Comment
Reporter 04-DEC-98 T.K. Bundtzen Pacific Rim Geological Consulting