Tub Mountain

Prospect in Alaska, United States with commodities Iron, Manganese

Geologic information

Identification information

Deposit ID 10001944
MRDS ID A012778
Record type Site
Current site name Tub Mountain
Related records 10160152

Geographic coordinates

Geographic coordinates: -165.75247, 64.78206 (WGS84)
Relative position The Tub Mountain prospect is on hill 956 in the SW1/4NW1/4 section 22, T. 8 S., R 35 W., Kateel River Meridian. It is 1.25 miles southwest of the confluence of Stewart and Sinuk Rivers and about 0.8 mile south of Sinuk River. The prospect is locality 6 of Hummel (1975) and locality 2 of Cobb (1972 [MF 463], 1978 [OFR 78-93]).
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Geographic areas

Country State
United States Alaska


Commodity Importance
Iron Primary
Manganese Secondary

Materials information

Materials Type of material
Goethite Ore
Hematite Ore
Pyrite Ore
Calcite Gangue
Dolomite Gangue
Quartz Gangue


  • (Local) Dolomitization and oxidation.

Nearby scientific data

(1) -165.75247, 64.78206

Comments on the geologic information

  • Geologic Description = The Tub Mountain prospect is a limonite-rich deposit about 300 by 600 feet that appears to be localized along high-angle faults in marble (Herried, 1970). It is one of several similar deposits in the area (see NM014, NM014, NM017, NM019, and NM020). The limonite can be massive to granular, botryoidal, mamillary, or fibrous. The iron content ranges to as much as 59 percent in analyzed samples (Eakin, 1915). Hematite, pyrolusite, and calcite are present locally. Shallit (1942; Mulligan and Hess, 1965, table 3) estimated that 8,000 long tons of rock containing 10 to 20 percent iron is present at Tub Mountain.? This prospect and other iron deposits of the Sinuk River area are at or near the base of massive marble whose protolith age is probably lower Paleozoic (Sainsbury, Hummel, and Hudson, 1972; Bundtzen and others, 1994). The deposits are locally controlled by high-angle faults or folds, but they are in general crudely stratabound within the basal massive marble or underlying calc-schist (Mulligan and Hess, 1965; Herreid, 1970). This stratigraphic interval also hosts base metal sulfide-fluorite-barite deposits at the Galena (NM130) and Quarry prospects (NM135).? the origin and age of the iron deposits of the Sinuk River area are uncertain. The deposits may be, in part, gossan developed on oxidized sulfide deposits (Eakin, 1915 [B 622-I, p. 361-365];Mertie, 1918 [B662-I, p. 425-449]; Cathcart, 1922; Mulligan and Hess, 1965; Herreid, 1970). Several of the iron deposits, including American (NM014) and Monarch (NM017), are locally highly anomalous in zinc and lead. Arguing against a simple gossan origin is the paucity of diagnostic textures and structures in boxworks that would suggest derivation from specific sulfide minerals. Alternatively, these deposits could be hypogene iron oxide and carbonate deposits probably transitional to lead-zinc-barite deposits, such as Quarry (NM135), that are at about the same stratigraphic position.? the age of the iron deposits of the Sinuk River area is most likely post-mid-Cretaceous because faults that crosscut mid-Cretaceous metamorphic rocks are an important ore control. A Late Cretaceous age for the iron deposits was suggested by Brobst and others (1971) as this is the age of fluorine-rich tin granites of northwestern Seward Peninsula (Hudson and Arth, 1983). The youngest possible age appears to be Early Tertiary, when deep weathering, sandstone-type uranium mineralization, and possibly karst formation occurred to the east in the Solomon quadrangle (Hudson, 1999).
  • Age = Late Cretaceous or Early Tertiary; post mid-Cretaceous metamorphism.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Nome

Reserves and resources

  • Type In-situ
    Estimate year 1942
    Total resources 3,000mt ore
    Remarks Entry carried over from Old MRDS or added later (i.e. it did not originate in ARDF)
    Commodity Subtype Grade units Group Importance Year
    Iron Fe 15 wt-pct Iron Major 1942

Comments on the reserve resource information

  • Reserves = Shallit (1942; table 3, Mulligan and Hess, 1965) estimated that the Tub Mountain prospect includes 8,000 long tons of rock containing 10 to 20 percent iron.

Comments on the workings information

  • Workings / Exploration = Surface prospecting pits, dating to before WWI, are present.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012778
USGS Alaska Resource Data File ARDF NM018

Bibliographic references

  • Deposit

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

  • Deposit

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

  • 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.

  • 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.

  • 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.

  • 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.

  • Deposit

    Sainsbury, C.L., Hummel, C.L., and Hudson, Travis, 1972, Reconnaissance geologic map of the Nome quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 72-326, 28 p., 1 sheet, scale 1:250,000.

  • 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.

  • 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.

  • Deposit

    Hudson, T.L., and Arth, J. G., 1983, Tin-granites of Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 94, p. 768-790.

  • Deposit

    Hudson, T.L., 1999, Alaska Resource Data File, Solomon quadrangle: U.S. Geological Survey Open-File Report 99-573, 360 p.

  • 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.

Comments on the references

  • Primary Reference = Herreid, 1970

General comments

Subject category Comment text
Deposit Model Name = Carbonate-hosted, iron oxide deposit.

Reporter information

Type Date Name Affiliation Comment
Reporter 22-OCT-99 Hawley, C.C. Hawley Resource Group
Reporter 22-OCT-99 Travis L. Hudson Hawley Resource Group