Unnamed (southwest of Monsoon Lake)

Occurrence in Alaska, United States with commodities Silver, Copper

Geologic information

Identification information

Deposit ID 10307473
Record type Site
Current site name Unnamed (southwest of Monsoon Lake)

Geographic coordinates

Geographic coordinates: -146.6907, 62.77863 (WGS84)
Relative position The occurrence is near the east end of a six-mile-long, east-trending ridge about 7 to 9 miles south of the Maclaren River. The occurrence is about 4 miles south-southwest of the center of Monsoon Lake. It is in the SE1/4NE1/4, section 34, T. 12 N., R. 8 W., Copper River Meridian, and is located accurately within 1000 feet.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Silver Primary
Copper Primary

Materials information

Materials Type of material
Bornite Ore
Chalcocite Ore
Chalcopyrite Ore
Malachite Ore

Mineral occurrence model information

Model code 90
USGS model code 24a
Deposit model name Massive sulfide, Cyprus
Mark3 model number 11

Host and associated rocks

  • Host or associated Host
    Stratigraphic age (youngest) Permian
    Stratigraphic age (oldest) Pennsylvanian

Nearby scientific data

(1) -146.6907, 62.77863

Comments on the geologic information

  • Geologic Description = This occurrence is near the east end of the so-called 'KFC anomalous zone', an elongated east-west zone about 10 miles long which includes the KFC prospect (GU001). This occurrence consists of rubble crop and is coincident with highly anomalous stream sediment values for copper (101-570 ppm ) reported by Castle and Degenhart (1978, figure 6) near the east end of the KFC anomalous zone. Bedrock is mainly composed of schistose basalt and andesite of the Pennsylvanian to Permian, Tetelna Formation. Work to the east of the area (Arehart, 1982) found numerous occurrences of: 1) veinlets and disseminations of bornite, chalcocite, and chalcopyrite; 2) local copper staining in epidotized volcanics; and 3) the Platypus Mountain prospect (GU003), which occurs in a felsic horizon in the volcanics.
  • Age = Diagenetic or epigenetic remobilization of copper and associated metals in volcanic host rocks of Pennsylvanian to Permian age. Remobilization of copper may have occurred during green-schist metamorphism in the Jurassic.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name Chistochina

Comments on the workings information

  • Workings / Exploration = The area was prospected on behalf of the Ahtna Native Regional Corporation in 1977 (Castle and Degenhart, 1978). An area immediately to the east was prospected by Noranda Inc. (Arehart, 1982). The exploration was only in reconnaissance.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF GU002

Bibliographic references

  • Deposit

    Castle, B., and Degenhart, C., 1978, Lichen Greenstone Belt, v. 9, 1977 Annual Progress Report, Ahtna Project: Anchorage, Alaska, WGM, Inc., 22 p., maps and appendices. (Report held by Ahtna Minerals Co., Anchorage, Alaska).

  • Deposit

    Arehart, G.B., 1982, Reconnaissance geology/geochemistry of the Alphabet Hills, Gulkana Quadrangle, Alaska: Noranda Exploration, 4 p., maps and appendices. (Report held by Ahtna Minerals Co., Anchorage, Alaska).

Comments on the references

  • Primary Reference = Castle and Degenhart, 1978

General comments

Subject category Comment text
Deposit Model Name = Cyprus massive sulfide (Cox and Singer, 1986, model 24a)
Deposit Other Comments = It is likely that detailed prospecting will find numerous, additional small occurrence of copper sulfide minerals in metamorphosed andesite and basalt in the area. Additional information can be obtained from Ahtna Minerals in Anchorage, Alaska.

Reporter information

Type Date Name Affiliation Comment
Reporter 20-DEC-00 W.T. Ellis Alaska Earth Sciences
Reporter 20-DEC-00 Hawley, C.C. Hawley Resource Group
Reporter 20-DEC-00 W.J. Nokleberg U.S. Geological Survey