Snowbird-Dry Creek: record NW5119

Region	West, Northwest
States	Montana
Mineral systems	Magmatic REE
Deposit types	Carbonatite Fluorspar
Commodities	copper magnetite phosphorus thorium uranium vermiculite yttrium
Critical minerals	fluorspar
Other minerals	barite beryllium fluorite niobium REE scandium strontium titanium zirconium

Information leading to the delineation of this focus area

Basis for focus area	Snowbird-Dry Creek: Lenticular quartz-calcite-fluorite-ankerite pegmatite bodies (Metz, 1971; Metz and others, 1985; Samson and others, 2004). Collapse and crackle breccias containing clasts of the host Wallace Formation in a matrix of quartz, calcite, and fluorite. Previously described as a pegmatitic carbonatite (Clabaugh and Sewell, 1964) and as a hydrothermal deposit (Sahinen, 1962). Polygon drawn to include related USMIN and MRDS localities of similar type and geologic setting. Includes Dry Creek site to the north, a 2 km buffer around the Snowbird deposit, and granitic rocks to the south near Lolo Pass.
Identified resources	Identified resources of fluorite and REE at Snowbird-Dry Creek. Past fluorite production.
Production	Approximately 6,500 short tons of metallurgical-grade fluorite were extracted from Snowbird from 1956 to 1957 (Metz, 1971; Samson and others, 2004).
Status	Past mining. Past exploration, trenching, and minor underground workings at Snowbird-Dry Creek.
Estimated resources	Unknown.
Geologic maps	Snowbird-Dry Creek: Lewis (1998b), scale 1:100,000; Lewis and Stanford (2002), scale 1:100,000.
Geophysical data	A high-resolution Earth MRI airborne magnetic and radiometric survey was funded by Earth MRI in 2021 and is in progress.
Favorable rocks and structures	Snowbird-Dry Creek: Mineralized quartz-calcite-fluorite-ankerite pegmatite bodies cutting Mesoproterozoic Wallace Formation.
Deposits	Snowbird-Dry Creek: Snowbird (MRDS dep_id: 10071392; USMIN Site_ID: MT00025).
Evidence from mineral occurrences	MRDS; USMIN.
Geochemical evidence	At Snowbird, a quartz zone surrounds a core containing ferroan calcite, ankerite, fluorite, and quartz with minor parisite, fluocerite, xenotime, pyrite, gersdorffite, and millerite (Metz, 1971; Metz and others, 1985; Samson and others, 2004). Parisite, a Ca-REE fluorocarbonate mineral typically associated with ankerite in the deposit, occurs as exceptionally large (up to 24 cm in length) and abundant crystals (Samson and others, 2004).
Geophysical evidence	Unknown.
Evidence from other sources	None.
Comments	Snowbird was a fluorite mine. The deposit is now a mineral collecting locality, primarily for crystals of quartz (up to 6 m in length) and parisite. No REE resource has been defined. Might also fit the Hybrid magmatic REE/Basin Brine setting mineral system table Hofstra and Kreiner (2020).
Cover thickness and description	The region is densely forested and soil cover may conceal other fluorite- and REE-bearing pegmatites. Snowbird itself is well-exposed from past exploration, trenching and minor underground workings.
Authors	Kaleb C. Scarberry, Stanley L. Korzeb, Jay A. Gunderson, Virginia S. Gillerman, Reed S. Lewis, Christopher A. Tate, Joshua M. Rosera, Allen K. Andersen.
New data needs	High resolution aeromagnetics, lidar, geochemistry, geologic mapping and trace element analysis of intrusions may reveal other exploration targets for REE.
Geologic mapping and modeling needs	Targeted 1:24,000 mapping and mine-site mapping would be beneficial.
Geophysical survey and modeling needs	Inadequate Rank 5 airborne magnetic and radiometric coverage.
Digital elevation data needs	Lidar inadequate. Lidar acquisition covering approximately 42,304 miles in Idaho beginning in 2019 does not cover areas this far north along the Idaho-Montana border.