Diamond Creek District

Location: Idaho, United States (45.291, -113.952 approx.)

Commodities: rare earth elements; thorium; gold

Geology

“Total rare-earth oxide content of eight samples from this district varied from 0.59 to 5.51 percent. The light cerium group of rare earths (lanthanum, cerium, praseodymium, neodymium, samarium, and europium) made up most of the rare earths in most of these samples although one sample had almost as much yttrium group of rare earths (gadolinium, terbium, dysprosium, holmium, erbium, thulium, lutetium, ytterbium, and yttrium) as light.” (Staatz and others (1979)) ”The veins of the Diamond Creek district are fine grained, limonitic, and similar in general appearance to many of those in the Lemhi Pass district. Quartz and limonite (generally goethite) make up a large part of these veins. Monazite is the principal thorium and rare-earth mineral. Thorium also occurs in minor amounts in some veins in brockite and thorite. In addition to these minerals, rare earths are found in minor amounts in some places in xenotime and bastnaesite. Fluorite, potassium feldspar, hematite, and biotite are locally abundant in some veins. In addition, small amounts of rutile, muscovite, montmorillonite, calcite, magnetite, plagioclase, malachite, pyrite, and gold were identified in one or more veins (Staatz, 1974, p. 498).” (Staatz and others (1979)) “The Diamond Creek district is approximately 8 mi north-northwest of the town of Salmon on the steep eastward-dipping slope of the Salmon River Mountains. The area is about 2,000 ft above the Salmon River, which flows along the eastern edge of the mountains. Diamond Creek crosses the district, and the principal veins occur on its drainage. Known veins in this small district, however, are found in an area that is approximately 2 1/2 mi long by 0.5 mi wide. Thorium veins were emplaced in to quartzite and siltite of Precambrian Y age and into granodiorite of the Idaho batholith of Cretaceous age. Most of the veins occur in the sedimentary rocks, which are approximately the same age as and, in part, lithologically similar to the rocks of the Belt Supergroup that are found farther north. The two groups of rocks were deposited in separate basins. The sedimentary rocks appear to be more favorable hosts than the igneous batholithic rocks as veins as much as 25 ft thick have been found in the former, but they rarely exceed 2 ft in the latter.” (Staatz and others (1979)) “The veins for which resources were calculated in the Diamond Creek district range in average thickness from 0.5 to 10 ft. Their average grade is from 0.07 to 0.30 percent ThO2 and from 0.59 to 4.92 total rare-earth oxides. Total reserves are 250 short tons of ThO2 and 2,870 tons of total rare-earth oxides. Total probable potential resources are 13,000 tons of ThO2 and 75,500 tons of total rare-earth oxides. The total of both categories amounts to 13,250 tons of ThO2 and 78,370 tons of total rare-earth oxides. In the calculations of the probable potential resources, two veins having similar strike and dip and lying along the same shear zone were connected across a small valley. The overall average grade of the reserves and resources is 0.21 percent Th02 and 1.22 percent total rare-earth oxides.” (Staatz and others (1979)) “Most of the prospecting consists of scattered bulldozer trenches and hand-dug pits. One of the larger veins was explored by a 25-ft adit, and a vein also is exposed in the road bed of the Diamond Creek road. As most of the Diamond Creek area is soil covered, veins are only exposed in workings. The lack of development has limited the tracing of veins, and only eight veins have been identified in this region. The vein that is exposed in the Diamond Creek road between two forks of Diamond Creek is interpreted as being the southern extension of the larger vein exposed on the ridge on the north side of Diamond Creek. All the veins have similar attitudes, ranging in strike from about N. 10 degrees E. to N. 60 degrees E.; all have steep dips. They follow irregular fractures in the country rock, and variations in strike of as much as 20 degrees have been noted on the same vein.” (Staatz and others (1979))

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.