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Roosevelt Hills

Prospect in Alaska, United States with commodities Silver, Tin, Arsenic, Bismuth, Copper, Manganese, Molybdenum, Lead, Uranium, Tungsten, Zinc
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Geologic information

Identification information

Deposit ID 10307707
Record type Site
Current site name Roosevelt Hills

Geographic coordinates

Geographic coordinates: -151.50495, 64.02157 (WGS84)
Relative position The Roosevelt Hills prospects cover about 10 square miles and are situated on the southeast flank of a rounded hill, locally termed hill 1910. The approximate center of the prospect area is in SW1/4SE1/4 section 29, T. 10 S., R. 20 W., of the Fairbanks Meridian. The Kantishna River flows within 11 miles, and there is an airstrip at Lake Minchumina approximately 30 miles southwest of the prospects. The Roosevelt Hills are situated on land selected by or conveyed to Doyon, Limited and in the Denali National Preserve.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Tin Primary
Arsenic Secondary
Bismuth Secondary
Copper Secondary
Manganese Secondary
Molybdenum Secondary
Lead Secondary
Uranium Secondary
Tungsten Secondary
Zinc Secondary

Materials information

Materials Type of material
Pyrite Ore
Coronadite Gangue
Fluorite Gangue
Quartz Gangue
Sericite Gangue
Tourmaline Gangue

Alteration

  • (Local) Numerous shear zones in granite are silicified and sericitized and contain a black coating in vugs and on joint surfaces. According to x-ray fluorescence analysis, this coating is coronodite: (Mn, Pb)Mn3O7. Burleigh (1989 [DLR 90-24]) inferred that the coating could be from downward-percolating supergene fluids.

Mineral occurrence model information

Model code 49
USGS model code 15c
Deposit model name Sn greisen

Nearby scientific data

(1) -151.50495, 64.02157
ListMap

Comments on the geologic information

  • Geologic Description = The Roosevelt Hills are composed of an elliptical, east-trending, muscovite-biotite granite stock and hornfelsed, pelitic schists (Burleigh, 1989 [DLR 90-24]). The age of the schist is unknown; the granite is Tertiary in age (Bond, 1985). The granite underlies several rounded hills and an adjacent eroded basin, covering approximately 10 square miles (Burleigh, 1989 [DLR 90-24]). Bond (1985) reported that the stock comprises early to late intrusive phases of granite, semi-porphyritic granite, equigranular granite, aplite, and quartz-tourmaline veins. The Roosevelt Hills stock is interpreted to be a deeply weathered, calc-alkaline, peraluminous granite (Burleigh, 1989 [DLR 90-24]). Regionally, the area contains a system of northeast-trending strike-slip and related conjugate faults associated with Cretaceous to Tertiary plutonic rocks and coeval or younger volcanic rocks (Clautice and others, 1993). The prospects consist of silicified-sericitized shear zones in the granite. One such zone, about 70 feet long and 30 feet wide, contains a black coating in vugs and on joint surfaces. According to x-ray fluorescence analysis, this coating is coronodite: (Mn, Pb)Mn3O7. (Burleigh, 1989 [DLR 90-24]) inferred that the coating could be from downward-percolating supergene fluids. Assays from the coronodite-bearing shears contained as much as 5,000 ppm Sn, 39.7 ppm Ag, 20,013 ppm Mn, and 2,688 ppm Pb (Burleigh, 1989 [DLR 90-24]). Bond (1985) reports that assays from the same zone contain 61percent Pb, 1,600 ppm Cu, 6,500 ppm Zn, 300 ppm Mo, 300 ppm As, 785 ppm Sn, and 60 ppm W. Adjacent areas with no coronodite coating contain as much as 3,100 ppm Pb, 500 ppm Zn, 16 ppm Mo, 7 ppm Ag, 1,400 ppm As, 6,800 ppm Sn, and 105 ppm W (Bond, 1985). In the northern half of the granite, widely spaced sets of coarse drusy quartz veins, 0.1 to 3 feet wide, trend 15 to 150 degrees and dip 70 degrees. According to x-ray fluorescence, these veins contain as much as 110 ppm Sn, with minor pyrite. Late-stage veins contain purple fluorite (Burleigh, 1989 [DLR 90-24]). Bond (1985) reported a rock chip that contained 12,600 ppm Sn. Pan concentrates from streams draining the granite contain as much as 4,200 ppm Sn, 9 ppm Pb, 66 ppm Zn, 9.8 ppm As, and 6 ppm U (Burleigh, 1989 [DLR 90-24]). Burleigh (1989 [DLR 90-24]) reported that the upper portions of the granite, which commonly contain large amounts of Sn, have been eroded. There are numerous alluvial deposits in the area with potential for Sn placers. Regional stream sediment sampling with airborne radiometrics in 1975-76 identified geochemical anomalies (Bond, 1985). In 1977, exploration efforts consisted of a scintillometer survey, mapping, and a stream sediment, rock chip, and soil sampling grid. Additional stream-sediment, rock chip, and water sampling was completed in 1980 (Bond, 1985). In 1981, an airborne radiometric program was conducted. Further rock chip sampling occurred in 1984. In 1985, two days of rubble and outcrop sampling identified hill 1910 as a Sn-rich zone in the granite (Bond, 1985). (Burleigh, 1989 [DLR 90-24]) conducted mapping activities and collected 18 rock chip and 10 pan concentrate samples. There are no indications of production.
  • Age = Veins cut Tertiary intrusion.

Economic information

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Inactive

Mining district

District name Kantishna

Comments on the production information

  • Production Notes = There are no indications of production.

Comments on the workings information

  • Workings / Exploration = Regional stream sediment sampling with airborne radiometrics in 1975-76 identified geochemical anomalies (Bond, 1985). In 1977, exploration efforts consisted of a scintillometer survey, mapping, and a stream sediment, rock chip, and soil sampling grid. Additional stream-sediment, rock chip, and water sampling was completed in 1980 (Bond, 1985). In 1981, an airborne radiometric program was conducted. Further rock chip sampling occurred in 1984. In 1985, two days of rubble and outcrop sampling identified hill 1910 as a Sn-rich zone in the granite (Bond, 1985). Burleigh (1989 [DLR 90-24]) conducted mapping activities and collected 18 rock chip and 10 pan concentrate samples.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF KH005

Bibliographic references

  • Deposit

    Cobb, E.H., 1977, Placer deposit map of central Alaska: U.S. Geological Survey Open-File Report 77-168B, 64 p., 1 map, scale 1:1,000,000.

  • Deposit

    Chapman, R.M., and Yeend, W., 1981, Geologic reconnaissance of the east half of the Kantishna River quadrangle and adjacent areas, in Albert, N.R.D., and Hudson, T., eds, The United States Geological Survey in Alaska, Accomplishments during 1979: U.S. Geological Survey Circular 823-B, 149 p.

  • Deposit

    Cobb, E.H., and Chapman, R.M., 1981, Mineral occurrences (other than mineral fuels and construction materials) in the Kantishna River and Ruby quadrangles, Alaska: U.S. Geological Survey Open-File Report 81-170, 94 p.

  • Deposit

    Bond, James, 1985, Geologic field examinations in Doyon Limited, regional selection block 9: Doyon Limited Report 85-19, 179 p. (Report held by Doyon, Ltd., Fairbanks, Alaska).

  • Deposit

    Clautice, K.H., Bowman, N.D., Clough, J.G., Gilbert, W.G., Kline, J.T., Smith, T.E., and Blodgett, R.B., 1993, Land selection Unit 8 (Kantishna River, Ruby, and Medfra quadrangles): References, lead isotope, geochemical and major oxide data: Alaska Division of Geological and Geophysical Surveys, 42 p., 1 sheet, scale 1:250,000.

  • Deposit

    Burleigh, Roger, 1989, Field report on mineral investigation of tin-granites of the Roosevelt Hills, Alaska: U.S. Bureau of Mines Field Report, 29 p.

  • Deposit

    Eakin, H.M., 1918, The Cosna-Nowitna region, Alaska: U.S. Geological Survey Bulletin 667, 54 p.

Comments on the references

  • Primary Reference = Burleigh, 1989 (DLR 90-24)

General comments

Subject category Comment text
Deposit Model Name = Shear-hosted veining, lower portion of Sn greisen deposits(?) (Cox and Singer, 1986; model 15c).
Deposit Other Comments = the Roosevelt Hills are situated on land selected by or conveyed to Doyon, Limited. For more information, contact Doyon, Limited. The site is also in Denali National Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 08-NOV-99 Cameron S. Rombach Alaska Division of Geological and Geophysical Surveys