American

Prospect in Alaska, United States with commodities Iron, Gold, Manganese, Zinc

Geologic information

Identification information

Deposit ID 10001943
MRDS ID A012777
Record type Site
Current site name American
Related records 10257526

Geographic coordinates

Geographic coordinates: -165.8733, 64.77622 (WGS84)
Relative position The American prospect is on a north-sloping face of a hill about 1 mile south of American Creek at an elevation of 600 feet. The prospect is about 2 miles west of a south-flowing part of Sinuk River and 2.3 miles northeast of a low divide near hill 660 on the Nome-Teller road. The location shown is taken from Herreid (1970) and is accurate within about 500 feet. This is locality 1 of Cobb (1972 [MF 463], 1978 [OFR 78-93]).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Iron Primary
Gold Secondary
Manganese Secondary
Zinc Secondary

Materials information

Materials Type of material
Goethite Ore
Limonite Ore
Pyrite Ore
Dolomite Gangue
Quartz Gangue

Alteration

  • (Local) Dolomitization, silicification, and oxidation.

Host and associated rocks

  • Host or associated Host
    Rock type Metamorphic Rock > Metasedimentary Rock > Marble

Nearby scientific data

(1) -165.8733, 64.77622

Comments on the geologic information

  • Geologic Description = Extensive amounts of limonite occur near a contact between marble and schist, probably along a high-angle fault that strikes west and is nearly coincident with the lithologic contact (Herreid, 197, figure 8). Surface rubble locally contains more than 30 percent goethite. The goethite-bearing rocks are associated with crackled dolomite and bleached, very light colored calcitic marble. The largest goethite-rich mass is about 600 feet long and as much as 150 feet across. The general iron-rich zone is about 1,800 feet long. The American lode is probably the second largest iron occurrence in the area, second only to the Monarch prospect (NM017). According to Shallit (1942), there are about 40,000 long tons of rock here that contain between 20 and 40 percent iron. Some of the deposit is anomalous in zinc. Herreid (1970, Appendix II) found as much as 800 ppm in zinc in soil samples collected north of the iron accumulation. One sample of silicified schist from this locality contained 0.06 ppm gold (Herried, 1970). The host rock to the iron accumulation is primarily marble and some intercalated metasedimentary schist.? 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 contolled 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 [B 662-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 that are transitional to some of the lead-zinc-barite deposits (as at the Quarry prospect, NM135) at the same stratigraphic horizon.? 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 control on them. 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). (Fluorite is abundant at the Quarry prospect.) 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 5,000mt 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 30 wt-pct Iron Major 1942

Comments on the reserve resource information

  • Reserves = Shallit (1942) estimated that 40,000 long tons of rock are present that contain 20 to 40 percent iron with minor manganese (also see Mulligan and Hess, 1965, p. 18).

Comments on the workings information

  • Workings / Exploration = A few surface prospecting pits to 6 or 8 feet deep are present here.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A012777
USGS Alaska Resource Data File ARDF NM014

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 = Iron deposit localized by marble-schist contact and intersecting fault.

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