Deposit

Monumental Summit

Monumental Summit is a deposit with published resource estimates in Idaho, recorded in the USGS USMIN rare earth element occurrence database (ver. 4.0, June 2019).

Facts on this page last re-verified Aug 12, 2026 — the oldest verification date among its current claims. How we verify.

Location: Idaho, United States (44.904, -115.267 approx.)

Commodities: rare earth elements

Deposit model: REE-Th bearing veins in shear zones · Th-REE veins

Geology

The rare-earth zone occurs within an apparent down dropped fault block of Precambrian metasedimentary Yellowjacket Formation consisting of quartzite; schist, and calcareous rock. "Rare-earth mineralization was apparently confined to tactite of the calcareous unit.." (Cater and others (1973))

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.

Material	Class	Amount	Grade	Contained	As of	Reference
rare-earth elements (REE)	Unclassified	86,200 t	3.6111 kilograms per metric ton	310.1 metric tons REE	Jan 1, 1973	Cater and others (1973), Page 98, Table 4 — Cater, F.W., Pinckney, D.M., Hamilton, W.B., Parker, R.L., Weldin, R.D., Close, T.J., and Zilka, N.T., 1973, Mineral resources of the Idaho Primitive Area and vicinity, Idaho: U.S. Geological Survey Bulletin 1304, p. 92–98.

Exploration and site history

Discovery — Discovered in 1966 by the USGS are a result of routine sampling with Idaho Primitive Area investigation, 1966 (Cater and others (1973))

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

Sources

U.S. Geological Survey · published Jun 1, 2019 · retrieved Aug 12, 2026 · archive unavailable: Wayback snapshot 20260427015518 of the ScienceBase item exists but the archive service returned 503 on verification 2026-08-12; recheck on a weekly pass