Bear Mountain

Occurrence in Alaska, United States with commodities Molybdenum, Tungsten, Lead

Geologic information

Identification information

Deposit ID 10001758
MRDS ID A012545
Record type Site
Current site name Bear Mountain
Related records 10257765

Geographic coordinates

Geographic coordinates: -142.15319, 68.36988 (WGS84)
Relative position Location is approximate center of area 1.25 mi (2 km) (east-west) by 0.35 mi (0.55 km )(north-south) of anomalous samples 517-521 and 608-13 of Barker (1981, pl. A-3); about 4 mi (6.4 km) southwest of Bear Mountain summit; known to within 2000 ft (610 m).???
(click for info)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Molybdenum Primary
Tungsten Primary
Lead Primary

Comments on the commodity information

  • Gangue = K-feldspar
  • Ore Material = Unidentified secondary ferromolybdate mineral
  • Ore Material = Unidentified secondary ferromolybdate mineral

Materials information

Materials Type of material
Galena Ore
Molybdenite Ore
Wolframite Ore
Goethite Gangue
Hematite Gangue
Jarosite Gangue
Kaolinite Gangue
Limonite Gangue
Magnetite Gangue
Muscovite Gangue
Quartz Gangue
Rutile Gangue
Topaz Gangue

Alteration

  • (Local) Core of sericitic and argillic alteration with outer zone of silicification; local peripheral areas of pyritic and propylitic alteration.

Host and associated rocks

  • Host or associated Associated
    Rock type Metamorphic Rock > Metasedimentary Rock
    Stratigraphic age (youngest) Mississippian
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite

Nearby scientific data

(1) -142.15319, 68.36988

Comments on the geologic information

  • Geologic Description = Tungsten-rich porphyry molybdenum occurrence. Area of about 1 sq km underlain by altered complex of rhyolite porphyry, quartz porphyry, and a pipe-shaped core of intrusive breccia about 300 m in diameter; complex is cut by dikes of rhyolite porphyry and aplite. Mineralized area defined by Mo-rich gossan zone trending NW for 1.5 km over 40 ha area characterized by soil samples containing 600 ppm Mo or greater; nearly coincident with 30 ha area of soil samples containing 500 ppm W or greater. Total area of Mo + W mineralization about 50 ha; vertical and horizontal zonation evident. Central Mo-rich gossan zone, outer zone of wolframite-topaz mineralization in a Fe-enriched upper-level phase of the complex below a silicified cap, and peripheral zone of Pb-enrichment. Sulfides have largely been oxidized to limonite, hematite, goethite, jarosite, and secondary ferromolybdates; wolframite occurs as disseminated grains in porphyritic rock, quartz veins, and silicified gossan. Molybdenite and galena have each been noted in only one locality. Tertiary rhyolite porphyry stock intrudes Mississippian and older metasedimentary rocks (Barker, 1981, p. 33-40, 106-137).

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Sheenjek

Comments on the workings information

  • Workings / Exploration = Rock samples taken in 1983 contain 0.1-0.8% M, 0.06-0.6% W, 2.2% F, 60-120 PPM Nb as reported in Barker and Swainbank (1985); soil sample 2521 on p. 141 of Barker (1981) from area of intrusive breccia contains 4900 ppm Mo, 860 ppm W, 400 ppm Pb and 9.7 ppm U (Barker, 1981, p. 140-150).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012545
USGS Alaska Resource Data File ARDF TB004

Bibliographic references

  • Deposit

    Barker, J.C., and Swainbank, R.C., 1986, A tungsten-rich porphyry molybdenum occurrence at Bear Mountain, northeast Alaska: Economic Geology vol. 81, p. 1753-9

  • Deposit

    Barker, J.C., 1978, Mineral Investigations of certain lands in the eastern Brooks Range: a summary report: US Bureau of Mines Open-File No. 63-78

  • Deposit

    Grybeck, D.J., 1977, Known mineral deposits of the Brooks Range, Alaska: US Geological Survey Open-File Report 77-166C, 41 p., 1 sheet, scale 1:1,000,000.

  • Deposit

    Brosge', W.P., and Reiser, H.N., 1976, Preliminary geologic and mineral resource maps (excluding petroleum), Arctic National Wildlife Range, Alaska: U.S. Geological Survey Open-File Report 76-539, 4 sheets, scale 1:500,000.

  • Deposit

    Cobb, E.H., 1973, Placer deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 p.

  • Deposit

    Brosgi, W.R., and Reiser, H.N., 1968, Geochemical maps of granitic rocks, Coleen and Table Mountain quadrangles, Alaska: U.S. Geological Survey Open-File Report 323, scale 1:250,000.

  • Deposit

    Cobb, E.H., Mayfield, C.F., and Brosge, W.P., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in eleven quadrangles in northern Alaska (Arctic, Baird Mountains, Chandler Lake, DeLong Mountains, Demarcation Point, Howard Pass, Misheguk Mountain, Mount Michelson, Noatak, Point Lay, and Table Mountain); Supplement to Open-File Report 75-628; Part A, Summaries of data to January 1, 1981: U.S. Geological Survey Open-File Report 81-767-A, 25 p.

Comments on the references

  • Primary Reference = Barker (1981)

General comments

Subject category Comment text
Deposit Model Name = Lode; Mo-W porphyry breccia
Deposit Other Comments = Part of regional E-W trend of small domes, intrusions and doubly-plunging anticlines.

Reporter information

Type Date Name Affiliation Comment
Reporter 20-SEP-1996 K.R. Leonard U.S. Geological Survey
Reporter 20-SEP-1996 D.F. Huber U.S. Geological Survey
Reporter 20-SEP-1996 J.M. Schmidt U.S. Geological Survey
Reporter 20-SEP-1996 J.H. Dover U.S. Geological Survey