Hall Mountain Group

Location: Idaho, United States (48.992, -116.422 approx.)

Commodities: rare earth elements; thorium

Deposit model: REE-Th bearing veins · Th-REE veins

Geology

“The U.S. Geological Survey (Staatz and others, 1979) determined that the possible reserves in this district are limited to thorium resources in only a few large veins. They estimate that the thorium reserves are 104,300 metric tons (115,000 tons) of vein material averaging 4.0 percent thorium oxide. They suggest that the rare earth elements are probably not economical in this district because of their low overall concentrations (average about 0.05 percent rare earth elements oxides).” (Long and others (2010)) “Mineralogically these veins differ considerably from most thorium veins. A comparison of the veins of Hall Mountain with those at Lemhi Pass on the Idaho-Montana border indicates the following differences: (1) at Hall Mountain veins contain only sparse limonite or hematite, but at Lemhi Pass these minerals are both widespread and abundant; (2) at Hall Mountain plagioclase was the only feldspar identified and it is rather sparse, whereas at Lemhi Pass microcline is one of the common gangue minerals, and plagioclase was not noted; (3) at Hall Mountain allanite is the second most common thorium and rare-earth mineral, and monazite and cenosite were found in one sample each, whereas at Lemhi Pass monazite is the second most common thorium and rare-earth mineral, brockite is common, and allanite is rare; (4) at Hall Mountains sphene, zircon, and ilmenite are present, but are absent from Lemhi Pass; and (5) barite is absent from Hall Mountain but common at Lemhi Pass.” (Staatz (1972)) “The first prospecting in this area was for gold and the base metals, and although considerable development has been done on some properties, no production is recorded. In the area studied the northern part has (Fig. 1) two veins at the Golden Scepter mine developed by two adits with about 3,100 feet of workings (Kiilsgaard, 1949, p. 29) and the southern part has a vein and a sulfide segregation in the base of a diorites still at the Montgomery mine explored by seven adits with about 3,200 feet of total workings (Kiilsgaard, 1949, p. 23). Radioactivity was first noted on a dump at the Golden Scepter mine in March 1955 (LeMoine, 1960, p. 19) by prospectors of the Northwest Prospecting and Development Company who originally thought it was caused by uranium (Clarence Sheldon, oral commun., 1970). This company subsequently found several other thorium veins in this area. The Northwest Prospecting and Development Company, which has since changed its name to the Atomic Fuels Corporation, had by 1970 either located or leased 20 claims in Hall Mountain (Clarence Sheldon, oral commun., 1970). South of this block of claims Irwin Scheller has found several veins (nos. 12, 13 and 14, Fig. 2) on his claims, and uphill to the northeast (no. 3, Fig. 2) Bruce Berringer has found thorium on T.M.U. no. 1.” (Staatz (1972)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010)) The veins of Hall Mountain cut Precambrian quartzite and quartz diorite. They range in exposed length from 1.8 to 213 m (6 to 700 ft) and vary in width from 0.18 to 4 m (0.6 to 13 ft). (Long and others (2010))

Published resource estimates

As compiled by USGS USMIN from the cited studies. Resource classes follow the source; "approximate" flags values USMIN reports as approximations. These are not current company reserve statements.

Record imported from USGS USMIN ver. 4.0 (June 2019). Developments after that date appear on facility records, not here; see the methodology.