Lost River

Site Name

Primary: Lost River
Secondary: Grothe-Pearson
Secondary: Tozer

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Commodity

Primary: Lead
Primary: Tin
Primary: Zinc
Primary: Silver
Primary: Beryllium
Primary: Copper
Primary: Fluorine-Fluorite

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Location

State: Alaska
District: Port Clarence

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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 Text: The veining and related replacement in this area can be thought of as distal alteration to more intense, tin metallization at depth. Mass balance calculations show significant SiO2, Al2O3, alkali, and fluorine enrichment with this type of alteration (Sainsbury, 1968, p. 1567).

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Cassiterite
Ore: Stannite
Ore: Sphalerite
Ore: Galena
Ore: Fluorite
Ore: Chrysoberyl
Gangue: Arsenopyrite
Gangue: Diaspore
Gangue: Pyrite
Gangue: Tourmaline

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Comments

Comment (Reference): Primary Reference = Sainsbury, 1969; Hudson, 1983

Comment (Commodity): Gangue = white mica

Comment (Geology): Age = The age of the mineralization is assumed to be related to the development of tin systems in the Lost River area and therefore Late Cretaceous, the age of the tin-mineralizing granites there (Hudson and Arth, 1983).

Comment (Exploration): Status = Active

Comment (Deposit): Model Name = Fluorite-, beryllium-, and sulfide-bearing veins and replacements in limestone (Sainsbury, 1968)

Comment (Production): Production Notes = None

Comment (Reserve-Resource): Reserves = Not defined

Comment (Geology): Geologic Description = Sainsbury (1969; 1972) maps the Rapid River fault as a 12-mile long east-west trending thrust fault in the southern part of the York Mountains although stratigraphic relations across the fault suggest normal displacement. Sainsbury (1969) indicates that the Rapid River fault is continuous for another 1.5 miles east of this prospect but earlier mapping (Sainsbury, 1964) suggests the possiblity that the Rapid River fault is offset by the north-south trending Lost River normal fault in the area of this prospect. Bedrock in the prospect area is Ordovician limestone locally cut by thin felsic dikes. Mineralization is probably at least locally present over about 5,000 feet of strike of the Rapid River fault including the Lost River valley and Bessie-Maple prospect (TE038) to the west. Soil samples across this prospect on the east side of Lost River are highly anomalous in base metals, tin, and beryllium (Sainsbury, 1969, plate 5). Mineralization exposed in dozer trenches is of several types; (1) fluorite and chyrsoberyl veins with diaspore, tourmaline , and white mica, (2) fluorite veins with or without fine-grained silica, (3) sulfide-bearing veins with stannite and related gossanous zones, and (4) quartz-muscovite- tourmaline-pyrite veinlets with up to 1.1% tin. Samples of the fluorite-beryllium mineralization contain 0.4 to almost 2% BeO and 50 to 59% fluorite (Sainsbury, 1963, p. 8). The complex, polymetallic character of the sulfide mineralization is well developed here as it is in the Bessie-Maple prospect to the west. Gossanous samples from trenches contain up to several percent lead, almost 1% copper, 4% zinc, 0.9% tin, 8 opt silver, and greater than 1,000 ppm arsenic (Hudson, 1983).

Comment (Workings): Workings / Exploration = Several surface dozer trenches and reconnaissance geochemical surveys have been completed on the bench east of Lost River.

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References

Reference (Deposit): Sainsbury, C.L., 1969, Geology and ore deposits of the central York Mountains, western Seward Peninsula, Alaska: U.S. Geological Survey Bulletin 1287, 101 p.

Reference (Deposit): Hudson, T.L., 1983, Interim report on the Lost River district, Seward Peninsula, Alaska: Anchorage, Alaska, Anaconda Minerals Company internal report (Report held by Cook Inlet Region, Inc., Anchorage, Alaska).

Reference (Deposit): Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Teller quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-587, 130 p.

Reference (Deposit): Sainsbury, C.L., 1964, Geology of the Lost River mine area, Alaska: U.S. Geological Survey Bulletin 1129, 80 p.

Reference (Deposit): Cobb, E.H., and Sainsbury, C.L., 1972, Metallic mineral resource map of the Teller quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-426, 1 sheet, scale 1:250,000.

Reference (Deposit): Sainsbury, C.L., 1972, Geologic map of the Teller quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Map I-685, 4 p., 1 sheet, scale 1:250,000.

Reference (Deposit): Sainsbury, C.L., 1963, Beryllium deposits of the western Seward Peninsula, Alaska: U.S. Geological Survey Circular 479, 18 p.

Reference (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.

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