Yankee Fork fluorspar

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

Information leading to the delineation of this focus area

Basis for focus area Belt of fluorspar prospects and occurrences (about 90 km long).
Identified resources Historical production of fluorite.
Production The Giant Spar property produced a few truckloads of fluorite during WWII (Shawe, 1976).
Status Past mining.
Estimated resources Unknown.
Geologic maps Fisher and others (1992), scale 1:250,000.
Geophysical data Mostly inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Fluorite occurrences follow a NE-trending lineament that cuts the Idaho batholith and Challis volcanic rocks. Fluorite veins occur in faults and breccia zones in quartz monzonite/granodiorite of the Idaho batholith, in epithermal Au-Ag veins, and associated with Challis volcanics.
Deposits Bright Star mine (MRDS dep_id: 10089181), Giant Spar mine (MRDS dep_id: 10089180), Homestake mine (MRDS dep_id: 10070998), Gold Chance mine (MRDS dep_id: 10105687), Hide Out prospect (MRDS dep_id: 10070995), Lamb prospect (MRDS dep_id: 10070972).
Evidence from mineral occurrences MRDS.
Geochemical evidence A sample from the Lamb prospect across a 4 foot (1.2 m) vein width contained 39.4% CaF2 and showed fluorite, calcite, chalcedony, quartz, and breccia.
Geophysical evidence Unknown.
Evidence from other sources Unknown.
Cover thickness and description Exposed at surface and reaches to some depth along veins.
Authors Virginia S. Gillerman, Reed S. Lewis, Christopher A. Tate, Jane M. Hammarstrom, Joshua M. Rosera.
New data needs High resolution geophysics, lidar.
Geologic mapping and modeling needs None requested at this time.
Geophysical survey and modeling needs High resolution, Rank 1 aeromagnetic and aeroradiometric coverage.
Digital elevation data needs Lidar inadequate; only small portion in progress.