Prospect in Alaska, United States with commodities Cobalt, Copper, Nickel, Silver, Gold, Iron

Geologic information

Identification information

Deposit ID 10002603
MRDS ID A015040
Record type Site
Current site name Chip-Loy
Related records 10185825

Geographic coordinates

Geographic coordinates: -154.38283, 62.16557 (WGS84)
Relative position The Chip-Loy deposit is located on a steep valley wall of Straight Creek at an elevation ranging from 2,900 feet (884 m) to 4,000 feet (1,220 m) in the SW1/4 sec. 15, T. 24 N., R. 28 W., of the Seward Meridian. Location is precisely known and visited by the reporter in 1983 and 1998. Caution: the precipitous, steep slopes that contain the Chip-Loy deposit are considered dangerous and are unsafe for traversing.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Cobalt Primary
Copper Primary
Nickel Primary
Silver Secondary
Gold Secondary
Iron Secondary

Comments on the commodity information

  • Ore Material = undetermined Co-Ni-Fe arsenide
  • Ore Material = nickelian pyrrhotite
  • Ore Material = violarite

Materials information

Materials Type of material
Bravoite Ore
Chalcopyrite Ore
Cubanite Ore
Galena Ore
Pentlandite Ore
Sphalerite Ore
Tetradymite Ore
Violarite Ore
Ilmenite Gangue


  • (Local) Slight oxidation of massive sulfides.

Mineral occurrence model information

Model code 13
USGS model code 7a
Deposit model name Synorogenic-synvolcanic Ni-Cu
Mark3 model number 19

Host and associated rocks

  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite > Diabase
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone

Nearby scientific data

(1) -154.38283, 62.16557

Comments on the geologic information

  • Geologic Description = According to Herreid (1968), Foley (1987), Nokleberg and others (1987), and Foley and others (1997), the Chip-Loy deposit consists of an irregular, steeply dipping layer of massive to disseminated, nickelian pyrrhotite accompanied by other sulfides in an elongate, composite, diabase intrusion. Herreid (1968) describes the diabase, which ranges from gabbro to diorite, as a pipe in plane view, but Smith and Albanese (1985) describe the same intrusion as a dike. The diabase trends in a northeast direction and varies from 40 meters to 260 meters wide; cliff walls prevent accurate investigations of the intrusion's true dimensions. The composite diabase intrusion cuts mid-Silurian Terra Cotta Mountains Sandstone, a formation of the Dillinger subterrane, a continental margin assemblage of Lower Paleozoic age. (Bundtzen, Harris, and Gilbert, 1997). Although undated, Gilbert and others (1988) assign the mineralized diabase intrusion an early Tertiary age.? the Chip-Loy deposit contains disseminated-to-massive sulfides, mainly pyrrhotite and chalcopyrite, and minor cubanite, and sphalerite, and trace galena, bravoite, violarite, tetradymite (Bi2Te2S), and undetermined Co-Ni-Fe arsenides (Bart Cannon, written communication, 1998). The sulfides are interwoven with ilmenite and other rock-forming minerals such as plagioclase and olivine. The northeast trending, sulfide-bearing zone occurs within the diabase about 10 to 30 meters away from the contact with sandstone and shale. The zone is about 335 meters long and 10 to 15 meters wide, but is quite irregular along strike. Herreid (1968) estimated that the Chip-Loy deposit contained an inferred reserve of about 150,000 tonnes of disseminated and massive sulfide mineralization. Smith and Albanese (1985) suggested a larger reserve than Herreid; they estimate from 0.15 to 1.25 million tonnes of sulfide mineralization exist at the Chip-Loy deposit. ? Chip-channel samples from the Chip-Loy deposit contain up to 3.30 percent nickel, 0.25 percent cobalt, 2.10 percent copper, 12.1 grams/tonne silver, and 43.2 percent iron (Smith and Albanese, 1985; Bundtzen, Roberts, and others, 1982). A single sample of massive sulfide mineralization contained 3.0 grams/tonne gold (Foley, 1987; Gilbert and others, 1988). Tetradymite was found in solid solution with rock-forming silicates--a typical PGE association--although no PGE has ever been detected in analyses of mineralized rock from the Chip-Loy deposit. A 12-meter-long chip-channel sample taken midway across the strike of the deposit contained 0.28 percent copper, 2.6 grams/tonne silver, 444 ppm cobalt, 0.70 percent nickel, and 17.82 percent iron (Smith and Albanese, 1985; Gilbert and others, 1988). Pyrrhotite from selected samples averages 0.4 percent cobalt and 1.5 percent nickel (Bart Cannon, written communication, 1998).
  • Age = Unknown; thought to be early Tertiary by Gilbert and others (1988).

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the reserve resource information

  • Reserves = Herreid (1968), who provides the only detailed geologic map of the Chip-Loy deposit, estimated that approximately 150,000 tonnes of disseminated-to- massive sulfide mineralization exists on site. Smith and Albanese (1985) estimate that between 0.15 and 1.25 million tonnes of disseminated to massive mineralization exist at the Chip-Loy deposit.

Comments on the workings information

  • Workings / Exploration = The Chip-Loy deposit was discovered and staked by prospectors Ed Chipp and Robert Loy in the early 1960s. Surface samples have been collected and analyzed by Herreid (1968), Bundtzen, Roberts, and others (1982), Smith and Albanese (1985), Roberts (1985), Gilbert and others (1988), Foley (1987), and T.K. Bundtzen and G.M. Laird (written communication, 1998). Chip-channel sample intervals from the Chip-Loy deposit run up to 3.30 percent nickel, 0.25 percent cobalt, 2.10 percent copper, 12.1 grams/tonne silver, and 43.2 percent iron. A 12 meter-long, chip-channel sample taken across the strike of the mineralized zone contained 0.70 percent nickel, 444 ppm cobalt, 0.25 percent copper, 2.6 grams/tonne silver, and 17.82 percent iron (Smith and Albanese, 1985; Gilbert and others, 1988).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A015040
USGS Alaska Resource Data File ARDF MG032

Bibliographic references

  • Deposit

    Smith, T.E., and Albanese, M.D., 1985, Preliminary prospect examinations in the McGrath B-2, A-3, and A-4 quadrangles, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 85-54, 19 pages.

  • Deposit

    Gilbert, W.G., Solie, D.N., and Kline, J.T., 1988, Geologic map of the McGrath A-3 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 92, 2 sheets, 1:63,360 scale.

  • Deposit

    Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p.

  • Deposit

    Foley, J.Y., 1987, Reconnaissance strategic and critical mineral investigations in the McGrath A-3 and B-2 quadrangles, southwest Alaska: U.S. Bureau of Mines Field Report, 26 pages.

  • Deposit

    Foley, J.Y., Light, T.D., Nelson, S.W., and Harris, R.A., 1997, Mineral occurrences associated with mafic-ultramafic and related alkaline complexes in Alaska: Economic Geology, Monograph 9, p. 396-449.

  • Deposit

    Herreid, G.H., 1968, Geological and geochemical investigations southwest of Farewell, Alaska: Alaska Division of Mines and Geology Geologic Report 26, 24 p., 1 sheet, scale 1:75,000.

  • 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 p., 1 sheet, scale 1:125,000.

  • Deposit

    Bundtzen, T.K., Kline, J.T., and Clough, J.G., 1982, Preliminary geologiy of the McGrath B-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File report 149, 22 p., 1 sheet, scale 1:40,000.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the McGrath quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-379, 1 sheet, 1:250,000 scale.

  • Deposit

    Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p.

Comments on the references

  • Primary Reference = Herreid, 1968

General comments

Subject category Comment text
Deposit Model Name = Gabbroic Ni-Cu (Cox and Singer, 1986; model 7a).
Deposit Other Comments = About 50 percent of the nickel and cobalt is believed to exist in pyrrhotite; the remainder is in pentlandite and other nickleiferous and cobaltiferous minerals.

Reporter information

Type Date Name Affiliation Comment
Reporter 30-OCT-1998 T.K. Bundtzen Pacific Rim Geological Consulting