Sischu Mountain

Site Name

Primary: Sischu Mountain

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Commodity

Primary: Tin
Secondary: Antimony
Secondary: Nickel
Secondary: Zirconium
Secondary: Gold
Secondary: Bismuth
Secondary: Arsenic
Secondary: Zinc
Secondary: Manganese
Secondary: Copper
Secondary: Molybdenum

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Location

State: Alaska
District: Ruby

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

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

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Physiography

Not available

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Mineral Deposit Model

Not available

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: On Sischu Mountain, float samples exhibit silicification and chlorite-kaolinite alteration and vein brecciation with tourmaline. An area identified by a color anomaly consists of hydrothermally brecciated sandstone fragments in a goethite matrix.

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Pyrite
Ore: Magnetite
Ore: Chalcopyrite
Gangue: Tourmaline
Gangue: Quartz
Gangue: Kaolinite
Gangue: Goethite
Gangue: Chlorite

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Comments

Comment (Exploration): Status = Inactive

Comment (Production): Production Notes = There are no indications of production.

Comment (Deposit): Model Name = Plutonic-related mesothermal veining.

Comment (Deposit): Other Comments = the Sischu Mountain prospects are located on land selected by or conveyed to Doyon, Limited. For more information, contact Doyon, Limited.

Comment (Geology): Age = Probably related to Cretaceous to Tertiary plutonism.

Comment (Reference): Primary Reference = Bond, 1985

Comment (Workings): Workings / Exploration = A regional stream sediment sampling, airborne radiometrics, and mapping program in 1975-76 and 1980 identified several anomalies. In 1984, one sample was collected. In 1985, exploration efforts consisted of mapping and collecting 12 rock chip, 7 stream sediments, and 8 pan concentrate samples (Bond, 1985). There are no indications of production.

Comment (Geology): Geologic Description = Sischu Mountain is composed of multiple igneous phases intruding phyllite, limestone, and siltstone to the north and various volcanic rocks, including rhyolite, dacite, andesite, and basalt, to the south and east (Chapman and Yeend, 1981). The phyllite, limestone, and siltstone are of Devonian age, and the intrusive rocks are Cretaceous to Tertiary (Chapman and Yeend, 1981). Float mapping has found aplite, coarse biotite granite, porphyry granite, hornblende-biotite monzodiorite, and porphyry dikes (Bond, 1985). 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). On Sischu Mountain, float samples exhibit silicification and chlorite-kaolinite alteration and vein brecciation with tourmaline. Disseminated pyrite and chalcopyrite occur in altered intrusive rock. Some aplite dikes contain as much as 1 percent magnetite. An area identified by a color anomaly consists of hydrothermally brecciated sandstone fragments in a goethite matrix. A rock chip of altered granite contained as much as 1,450 ppm As, 25 ppm Bi, 100 ppm Sn, and 15 ppm Mo (Bond, 1985). Clautice and others (1993) reported analyses of several samples: (1) a rhyolite dike cutting limestone contained as much as 1,200 ppm Zr, 86 ppm Cu, 542 ppm Zn, 265 ppm Ni, 136 ppm As, 35 ppm Sb, 799 ppm Mn, and 10 ppm Sn; (2) limestone near a granitic contact contained as much as 114 ppm As; (3) equigranular, biotite monzonite contained 767 ppm Zn, 47 ppm As, 23 ppm Pb, and 6 ppm Sn; (4) a rhyolite dike in limestone contained 132 ppm As, 590 ppm Mn, and 38 ppm Pb; and (5) limonitic rhyolite contained 105 ppm As and 463 ppm Mn. A regional stream sediment sampling, airborne radiometrics, and mapping program in 1975-76 and 1980 identified several anomalies. In 1984, one sample was collected. In 1985, exploration efforts consisted of mapping and collecting 12 rock chip, 7 stream sediments, and 8 pan concentrate samples (Bond, 1985). There are no indications of production.

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References

Reference (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.

Reference (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.

Reference (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.

Reference (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.

Reference (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).

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

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