THORIUM MINERALIZATION IN THE LEMHI PASS AREA, LEMHI COUNTY, IDAHO
The thorium mineralization in the Lemhi Pass area of southeastern Lemhi County, Idaho, is directed along simple to complex shear and fracture zones, and reopened copper and gold-quantz veins and lodes, in impure quartzitic and phyllitic rocks of the Precambrian Belt series. Some of the shear and fracture zones are more than 40 ft across and comprise broad zones of irregularly mineralized rock reaching distances to 2000 ft in length. These zones contain notable concentrations of thorium and rareearth elements along with considerable amounts of Ba, alkali metals, Ca, Fe, P, S, and Si and meager amounts of Nb, U, and perhaps other related elements. Minerals identified so far include thorite, allanite, monazite, xenotime (?), euxenite(?), apatite, specularite, barite, alkali feldspar, calcite, biotite, phlogopite, sericite, chalcedony, and quartz. The most characteristic minerals are thorite, specularite, barite, and quartz. The specularite and thorium-bearing minerals are intimately associated and were introduced into the deposits after the Micas and in advance of the barite, feldspar, calcite, and quartz. Except for the specularite and quartz and in part the barite, feldspar, calcite, and thorite, the minerals are not distinguishable without the microscope. Some of the deposits contain several per cent thoria and comparable amounts of rareearth oxides, but the average is generally under 1%. The area has an appreciable reserve of lode thorium. Some of the deposits are in or are being brought into production. (auth)
- Research Organization:
- Cornell Univ., Ithaca, N.Y.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-15-013174
- OSTI ID:
- 4077226
- Journal Information:
- Economic Geology and the Bulletin of the Society of Economic Geologists (U.S.), Vol. Vol: 56; Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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