Post Lake

Prospect in Alaska, United States with commodities Arsenic, Cobalt, Copper, Nickel, Iron, Lead

Geologic information

Identification information

Deposit ID 10307867
Record type Site
Current site name Post Lake

Geographic coordinates

Geographic coordinates: -153.52781, 62.12048 (WGS84)
Relative position The Post Lake prospect is located about 1 mile (1.5 km) east of Post River and 1.8 miles (2.9 km) south of Post Lake on a low, glaciated bench level in sec. 32, T. 24 N., R. 23 W., of the Seward Meridian. Location is precisely known; the reporter investigated the mineralization in 1983.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Arsenic Primary
Cobalt Primary
Copper Primary
Nickel Primary
Iron Secondary
Lead Secondary

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Pyrrhotite Ore
Quartz Gangue

Alteration

  • (Local) Ferricrete oxidation of massive pyrrhotite zones is extensive and ubiquitous.

Mineral occurrence model information

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

Nearby scientific data

(1) -153.52781, 62.12048

Comments on the geologic information

  • Geologic Description = The Post Lake prospect consists of massive, sulfide veins and replacement zones that cut Ordovician to Lower Silurian shale of the Post River Formation, a unit of the Dillinger subterrane (Bundtzen and others, 1988; Bundtzen, Harris, and Gilbert, 1997). The mineralized area is about 122 meters south of the contact between the Post River Formation and a small quartz monzonite stock. A prospect map has been published by Bundtzen and others (1988). Most of the sulfide mineralization consists of massive pyrrhotite, and minor to sparse chalcopyrite and arsenopyrite. Sulfide masses vary from 0.5 to 2 meters in thickness and strike lengths of 20 to 80 meters. Most of the mineralization trends about N25W, parallel to the nearby Bowser Creek fault. . Bundtzen and others (1988) reported values as high as 570 ppm copper, 302 ppm zinc, 378 ppm arsenic, 139 ppm cobalt, and 637 ppm nickel. Five chip samples taken across the massive sulfides averaged about 33.5 percent iron. Elevated cobalt and nickel values occur in the massive pyrrhotite zones.
  • Age = Inferred to be Tertiary based on ages of plutonic suite in area (Solie and others, 1991).

Economic information

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Only surface sampling has been conducted. Bundtzen and others (1988) reported values as high as 570 ppm copper, 302 ppm zinc, 378 ppm arsenic, 139 ppm cobalt, and 637 ppm nickel. Five chip samples taken across the massive sulfide zones averaged about 33.5 percent iron. Elevated cobalt and nickel values occur in the massive pyrrhotite zones.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MG069

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

    Bundtzen, T.K., Kline, J.T., Smith, T.E., and Albanese, M.D., 1988, Geology of the McGrath A-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 91, 18 p., 1sheet, scale 1:63,360.

Comments on the references

  • Primary Reference = Bundtzen and others, 1988

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins (Cox and Singer, 1986; model 22c).
Deposit Other Comments = Geological features are similar to Chip-Loy prospect (MG032) in McGrath A-3 quadrangle.

Reporter information

Type Date Name Affiliation Comment
Reporter 13-OCT-98 T.K. Bundtzen Pacific Rim Geological Consulting