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A Columbium-Bearing Regolith on Upper Idaho Gulch, Near Tofty, Alaska.

Authors
Warner-JD; Mardock-CL; Dahlin-DC
Source
MISSING :29 pages
Link
NIOSHTIC No.
10005473
Abstract
In 1984, as part of a project to evaluate Alaskan occurrences of certain critical and strategic minerals, the Bureau of Mines investigated a columbium-bearing regolith on Upper Idaho Gulch, near Tofty, Alaska. The regolith is derived from weathering of a dolomitic marble and consists mostly of iron oxide minerals with accessory apatite, zircon, xenotime, rutile, monazite, and the columbium minerals aeschynite, columbite, and ilmenorutile. Two regolith lenses contain 340,000 lb of columbium resources at an average grade of 0.07 pct. Calculated composite concentrates from two regolith samples (approximately 200 lb each) contained 53 and 57 pct of the columbium at grades of 0.97 and 0.86 pct, respectively. In each case the grade could be improved to 1.1 pct cb with a sacrifice of 9- pct recovery. The regolith's mineralogy, trace-element geochemistry, and similarity to descriptions of other columbium- enriched regoliths suggest that the underlying marble may be a carbonatite. The lack of associated alkalic igneous rocks and the stratiform nature of the regolith, however, may be interpreted as evidence for sedimentary origin of the marble. The marble and regolith are a lode source for some of the minerals in the Idaho gulch placer deposit.
Publication Date
19860101
Document Type
IH; Information Circular;
Fiscal Year
1986
NTIS Accession No.
NTIS Price
Identifying No.
IC 9105
NIOSH Division
AFOC;
Source Name
MISSING
State
AK; ID;
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