Fish Springs

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

Information leading to the delineation of this focus area

Basis for focus area Outline of the Fish Springs mining district from Krahulec (2018b).
Identified resources Identified resources of copper, indium, and zinc. Historical production of lead and silver.
Production Unknown.
Status Past mining; current exploration.
Estimated resources Indicated and Inferred sulfide plus oxide resource totaling over 66 million tonnes including 1.3 million tonnes Zn, 140,000 tonnes Cu, 1.6 million kg In, and 19.5 million tonnes Fe (Dyer and others, 2014).
Geologic maps Hintze (1980), scale 1:500,000.
Geophysical data Inadequate Rank 4 aeromagnetic coverage.
Favorable rocks and structures The main ore hosts are the Ordovician Ely Springs Dolomite and Pogonip Group and deeper mineralization in the Cambrian Orr Formation. Two ore zones are separated by the Juab fault, a west-northwest-trending, north-dipping normal fault. The fault is significant enough to have caused a conspicuous left-lateral offset of the Fish Springs Range and is thought to have on the order of 500-600 m of net vertical displacement (Dyer and others, 2014).
Deposits Utah mine (MRDS dep_id: 10020409), Galena mine (MRDS dep_id: 10020408), West Desert (Crypto) Zn-In-Cu skarn.
Evidence from mineral occurrences MRDS; UMOS (Utah Geological Survey, 2021).
Geochemical evidence Lead-Ag vein and replacement ores in the Silurian Laketown Dolomite are strongly anomalous in As, B, Cd, Mn, Mo, V, and Zn (Krahulec, 2018b). Mineralization at West Desert consists of sphalerite with lesser chalcopyrite occurring commonly with massive magnetite in skarn and replacement bodies. Indium occurs predominantly as lattice substitution in sphalerite.
Geophysical evidence A very strong magnetic high in the pediment led to drill testing and the discovery of a pair of unexposed stocks and a deep magnetite-sphalerite skarn (Krahulec, 2018b).
Evidence from other sources Krahulec (2018b).
Comments Airborne data collection unlikely to be possible given airspace restrictions. Indium is present in unusually high levels within sphalerite at West Desert, measuring up to 9% in sphalerite. The 2014 Indicated and Inferred resource is one of the largest undeveloped In resources in the world. Less than 35% of drill hole samples for the historical resource were assayed for In, indicating potential to significantly increase the In resource at West Desert with further sampling, exploration and studies. Likewise, In is also known to substitute into magnetite, so further In potential may be present in the magnetite portions of the orebody. There has also been little research on other critical mineral potential, such as Ga and Ge.
Cover thickness and description 15 to 200 m pediment alluvium for the Main Zone, 500 m under Notch Peak Dolomite in the Deep Zone.
Authors Stephanie Mills.
New data needs Digitization of current maps.
Geologic mapping and modeling needs Digitization.
Geophysical survey and modeling needs None requested at this time (area constrained by No-Fly zone).
Digital elevation data needs Lidar inadequate.