Deposit

Rocky Boy

Rocky Boy is a rare earth occurrence in Montana, 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: Montana, United States (48.170, -109.713 approx.)

Commodities: rare earth elements

Deposit model: carbonatite · carbonatite deposits

Geology

Rare earth minerals are associated with the carbonatite-alkaline rock complex at the head of the Big Sandy Creek. Two rare earth carbonate minerals, burbankite and calkinsite, have been obtained from test pits about 1000 feet southwest of the entrance in the Number One adit. Many veinlets and disseminations rich in burbankite were intersected in a drill hole at depths between 283 and 375 feet. The drill hole collar is about 200 feet east of the entrance to the Number One adit. (Lindsey and others (1977))

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