Snowbird-Dry Creek

Region West, Northwest
Mineral systems
Deposit types
Critical minerals
Other minerals

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.