Cub Bear

The Cub Bear is a iron and manganese mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Cub Bear

Commodity

Primary: Iron
Primary: Manganese
Secondary: Zinc
Secondary: Silver
Secondary: Lead

Location

State: Alaska
District: Nome

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Not available

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Dolomitization peripheral to iron oxide mineralization.

Rocks

Role: Host
Age Type: Host Rock
Age Young: Campanian
Age Old: Barremian

Analytical Data

Not available

Materials

Ore: Galena
Ore: Goethite
Ore: Hematite
Ore: Pyrite
Ore: Pyrolusite
Ore: Sphalerite
Gangue: Dolomite
Gangue: Quartz

Comments

Comment (Commodity): Gangue = sericite (white mica)

Comment (Deposit): Model Name = Iron oxide veins and replacement of marble and schist.

Comment (Reference): Primary Reference = Herreid, 1970

Comment (Geology): Age = Post mid-Cretaceous, the age of metamorphism of the host schist and marble.

Comment (Geology): Age = Host rock is Pre Campanian - Post Barremian.

Comment (Exploration): Status = Inactive

Comment (Geology): Geologic Description = The Cub Bear prospect is a ferruginous zone about 3,000 feet long and as much as 200 feet across that strikes north-northwest (Herreid, 1970, figure 6). The prospect contains a mineralized zone near Herreid's samples 1, 2, and 3 that contains anomalous zinc. The main concentration of iron is near Herreid's samples 4, 5, and 6, approximately 1,500 feet north of the zinc-bearing samples. Bedrock exposure is poor at the prospect. According to Herreid (1970, p. 28), the rubble overlying the deposit consists of goethite, dark yellow-brown ferruginous marble, crackled dolomite, medium-grained marble, and fine-grained ferruginous material. Crackled dolomite locally has goethite veinlets, with goethite psuedomorphic after pyrite. Dolomite breccia appears to form a discontinuous envelope around the iron-rich deposit.? the mineralized zone is essentially in marble of the massive marble unit of Bundtzen and others (1994); it occurs along a high-angle fault that separates the massive marble unit to the west from the graphitic schist unit to the east. The mineralized unit is most likely the lowermost massive marble, a unit that Herreid (1970) mapped in thrust contact with underlying mica schist.? the prospect has a small iron resource estimated by Shallit (1942; Mulligan and Hess, 1965, table 3) to be 10,000 long tons with 10 to 20 percent iron and a small tonnage of material containing 30 to 45 percent iron. A sample of goethite collected by Herreid contained 16 percent iron. The prospect also is locally anomalous in zinc. Samples from the south part of the prospect (Herreid's localities 1 to 3) contained as much as 2.4 percent zinc in a 10-foot chip sample. A 100-foot-long sample, collected near Herried's samples 3 to 6, contained 1,650 ppm zinc. The lead content of these samples did not exceed 67 ppm, and silver content did not exceed 1.3 ppm; no gold was detected.? the iron deposits of the Sinuk River area have generally been interpreted as gossan developed on oxidized sulfide deposits. At the Cub Bear prospect, there is some iron oxide (goethite) psuedomorphic after pyrite, consistent with this mode of origin. Alternatively, the deposits are primarily hypogene iron oxide deposits that are transitional into the carbonate-hosted base metal-fluorite-barite deposits of the area, such as at the Quarry prospect nearby (NM135). The relatively high zinc content of the Cub Bear prospect is consistent with the latter possibility. The age of the deposit is almost certainly post mid-Cretaceous, the age of metamorphism of the host marble. A Late Cretaceous origin was argued for the Quarry prospect by Brobst and others (1971).

Comment (Workings): Workings / Exploration = The Cub Bear prospect was developed by a series of pits and trenches before 1915 (Eakin, 1915 [B 622-I, p. 361-365]). Mertie (1918 [B 662-I, p.446]) reported that no recent work was evident in 1916. Cathcart (1922, p. 261), however, reported exploration by 12 trenches, 20 to 30 feet long and about 3 feet deep. The prospect was visited by Shallit (1942) and Mulligan (Mulligan and Hess, 1965) who estimated resources of iron at the prospect. Herreid (1970, figure 6) prepared a map of the prospect at 1:6000 scale. Herreid also assayed samples for gold, silver, copper, lead, and zinc.

Comment (Reserve-Resource): Reserves = the prospect has been estimated to contain 100 tons of material with 30 to 45 percent iron and 10,000 tons with 10 to 20 percent iron (Shallit, 1942). There is some manganese oxide.

References

Reference (Deposit): Shallit, A.B., 1942, Report on Sinuk River iron-ore deposits, Seward Peninsula, Alaska: Alaska Territorial Department of Mines Minerals Investigation, 46 p., 2 maps, scales 1:31,250, 1:4,800.

Reference (Deposit): Brobst, D.A., Pinckney, D.M., and Sainsbury, C.L., 1971, Geology and geochemistry of the Sinuk River barite deposits: U.S. Geological Survey Professional Paper 750-D, p. D1-D8.

Reference (Deposit): Bundtzen, T.K., Reger, R.D., Laird, G.M., Pinney, D.S., Clautice, K.H., Liss, S.A., and Cruse, G.R., 1994, Progress report on the geology and mineral resources of the Nome mining district: Alaska Division of Geological and Geophysical Surveys, Public Data-File 94-39, 21 p., 2 sheets, scale 1:63,360.

Reference (Deposit): Mulligan, J.J., and Hess, H.D., 1965, Examination of the Sinuk iron deposits, Seward Peninsula, Alaska: U.S. Bureau of Mines Open-File Report 8-65, 34 p.

Reference (Deposit): Herreid, G.H., 1970, Geology and geochemistry of the Sinuk area, Seward Peninsula, Alaska: Alaska Division of Mines and Minerals Geologic Report 36, 61 p., 3 sheets, scale 1:42,000.

Reference (Deposit): Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Nome quadrangle, Alaska: U.S. Geological Survey Open-File report 78-93, 213 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Nome quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-463, 2 sheets, scale 1:250,000.

Reference (Deposit): Cathcart, S.H., 1922, Metalliferous lodes in southern Seward Peninsula: U.S. Geological Survey Bulletin 722, p. 163-261.

Reference (Deposit): Eakin, H.M., 1915, Placer mining in Seward Peninsula: U.S. Geological Survey Bulletin 622-I, p. 366-373.

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