Unnamed (west of the Middle Fork Chandalar River)

Occurrence in Alaska, United States with commodities Lead, Zinc, Silver, Copper

Geologic information

Identification information

Deposit ID 10001727
MRDS ID A012511
Record type Site
Current site name Unnamed (west of the Middle Fork Chandalar River)
Related records 10112117

Geographic coordinates

Geographic coordinates: -147.82335, 68.03976 (WGS84)
Relative position Site is at an elevation of about 3,750 ft. in a small drainage approximately 2 miles west of the Middle Fork Chandalar River and about 7 miles south of the confluence of Beaucoup Creek and Middle Fork Chandalar River (south-center sec. 19, T. 16 S., R. 19 E., of the Umiat Meridian). It is described as Area B on fig. 1 in Detra (1977). Location accurate within 1/4-mile radius.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Lead Primary
Zinc Primary
Silver Secondary
Copper Secondary

Comments on the commodity information

  • Ore Material = iron sulfides
  • Ore Material = iron sulfides

Materials information

Materials Type of material
Chalcopyrite Ore
Galena Ore
Sphalerite Ore
Tetrahedrite Ore
Quartz Gangue

Mineral occurrence model information

Model code 224
USGS model code 32a
BC deposit profile E12
Deposit model name Mississippi Valley, S.E. Missouri Pb-Zn
Mark3 model number 42

Host and associated rocks

  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Pyroclastic Rock > Volcanic Breccia (Agglomerate)
    Rock unit name Skajit Limestone;Beaucoup Formation; Brown Shale Member
    Rock description Skajit Limestone;Beaucoup Formation; Brown Shale Member

Nearby scientific data

(1) -147.82335, 68.03976

Comments on the geologic information

  • Geologic Description = One of two mineralized areas with small outcrops within which lead-zinc-silver-(copper) mineralization is found (Detra, 1977). The mineralization is described as occurring in quartz veins in a chert breccia cap on limestone. Samples from the veins are reported to contain galena, sphalerite and chalcopyrite as well as iron sulfides. Exposures of mineralization are less than 3 meters in length and not much wider than the streams (approximately 1 to 2 meters) in which they are exposed. Two samples taken from the mineralized area returned analyses as high as 25% Zn, [more than] 2% Pb and 150 ppm Ag (Detra, 1977). The chert breccia cap which hosts the mineralization occurs locally at the top of the Skajit Limestone at an unconformity that has been interpreted as a paleokarst surface. The chert cap is overlain by yellow-weathering phyllitic siltstones, shales and sandstones, which in turn are overlain by black shales of the Hunt Fork Shale. The surrounding area is mapped as Devonian shale, sandstone and conglomerate with scattered bodies of mafic rocks of uncertain age (Detra, 1977).

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Chandalar

Comments on the workings information

  • Workings / Exploration = 57 claims in two claim blocks located by Noranda and RAA in 1977.?Semi-quantitative spectrographic data (Detra, 1977) from rock samples from the area include: sample number 232RA - Ag (150 ppm), Ba (200 ppm), Cu (700 ppm), greater than 20,000 ppm Pb and Zn. Zn by wet chemical analysis - 250,000 ppm; sample number 232RB - Ag (30 ppm), Ba (300 ppm), Cu (150 ppm), Pb (15,000 ppm), greater than 20,000 ppm Zn. Zn by wet chemical analysis - 75,000 ppm (Detra, 1977, table 1).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012511
USGS Alaska Resource Data File ARDF PS007

Bibliographic references

  • Deposit

    Cathrall, J.B., Cooley, E.F., Detra, D.E., and O'Leary, R.M., 1977, A listing and statistical summary of spectrographic and chemical analysis of stream-sediment and rock samples from the Philip Smith Mountains quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-244, 79 p.

  • Deposit

    Detra, D.E., 1977, Delineation of an anomalous lead-zinc area in the Philip Smith Mountains A-2 quadrangle, Alaska: U.S. Geological Survey Open-File Report 77-223, 11 p.

  • 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

    Dutro, J.T., Jr., 1978, Potential stratabound lead-zinc mineralization, Philip Smith Mountains quadrangle, Alaska, in Johnson, K. M., ed., The United States Geological Survey in Alaska, Accomplishments during 1977: U.S. Geological Survey Circular 772-B, p. B9-B11.

  • Deposit

    Menzie, W.D., Reiser, H.N., Brosgi, W.P., and Detterman, R.L., 1985, Map showing distribution of mineral resources (excepting oil and gas) in the Philip Smith Mountains quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Investigations Map MF-879-C, 2 sheets, scale 1:250,000.

  • Deposit

    Schmidt, J.M., 1997, Shale-hosted Zn-Pb-Ag and barite deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska, 1997: Economic Geology Monograph 9, p. 35-65.

  • Deposit

    Maas, K.M., 1987, Availability of land for Mineral exploration and development in northern Alaska, 1986: U.S. Bureau of Mines Special Publication, 34 p., 33 sheets.

Comments on the references

  • Primary Reference = Detra, 1977

General comments

Subject category Comment text
Deposit Model Name = Mississippi Valley Zn-Pb (?) (Cox and Singer, 1986; model 32a).
Deposit Other Comments = See also locations PS006 and PS008. Site is in an area thought to have potential for carbonate-hosted lead-zinc deposits (Menzie and others, 1985). The pH of the stream that cuts the mineralization is less than 4.5.

Reporter information

Type Date Name Affiliation Comment
Reporter 17-NOV-1999 J.M. Britton U.S. Geological Survey