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

Information leading to the delineation of this focus area

Basis for focus area Lithocap alunite, Polymetallic Replacement, Porphyry Molybdenum, Volcanogenic U based on outlines of Krahulec (2018b). This area includes the Alunite Ridge vein deposits and Deer Trail polymetallic replacement deposit to the south, and the Marysvale alunite area to the north. Possibly byproduct W, Sn, Nb, REE, from Mo resources and Ga from alunite resources.
Identified resources Identified resources of aluminum (alunite), manganese, and uranium. Historical production of aluminum (alunite) fluorite, manganese, and uranium.
Production Several hundred" tons of manganese ore produced (Dry Creek Mn) and small production from Blue Miami Moon no.1 (Crittenden, 1951). A few hundred tons of ore with approximately 40% Mn produced from Georgia mine.
Status Past mining (1952-1966); reserves development; alunite was mined for potassium sulfate during WWI, and possibly mined for aluminum during WWII. Current carbonate replacement exploration at Deer Trail.
Estimated resources Total resources as of 2006: 3,750,000 metric tons at 0.039% U3O8; Hall (1978) Estimated resources of 2.12 Mt of ore @ >80% alunite in veins and 40.62 Mt of ore @ >23% alunite in replacement deposits. Approximately 1,000 metric tons at 5% Mn (Blackbird). Potential for a few thousand tons at 25 to 35% Mn associated with Dry Canyon Claims (Crittenden, 1951).
Geologic maps Rowley and others (2005), scale 1:100,000; Hintze and others (2008), scale 1:100,000; Rowley and others (1988), scale 1:24,000; Steven and Cunningham (1979), scale 1:24,000; Cunningham and Steven (1979), scale 1:24,000.
Geophysical data Inadequate aeromagnetic coverage and adequate aeroradiometric coverage.
Favorable rocks and structures Hydrothermally altered porphyritic flows and tuffs (argillic alteration). Siliceous sinter knobs associated with hot spring centers. Vein and fissure-filling fluorite. Manganese associated with veins, often in volcanic rocks, along the Sevier fault.
Deposits Marysvale Peak (MRDS dep_id: 10088078, alunite), Fluorite mine (MRDS dep_id: 10108867, fluorite), Dry Creek Manganese, Blackbird, Georgia mine (MRDS dep_ids: 10010342, 10015215, 10103846, manganese).
Evidence from mineral occurrences MRDS; UMOS (Utah Geological Survey, 2021).
Geochemical evidence Sample across veins in Blackbird mine: 14 to 17% Mn. Estimated 35 tons with 20% Mn stockpiled in front of pit at Blackbird (Crittenden, 1951). Numerous fluorite (associated with uranium) and manganese veins (post-volcanic) throughout study area. Potential for byproduct antimony (tertiary commodity in at least one base metal mine).
Geophysical evidence Aeromagnetics and gravity surveys in Campbell and others (1999).
Evidence from other sources See Krahulec (2018b).
Comments Potentially many overlapping deposit types related to Climax-type mineral system. Enrichment of many critical commodities has been inferred from the mineral system/deposit type table (Hofstra and Kreiner, 2020), but requires further verification. These include: As, Be, Bi, Ge, In, K2SO4 (potash), Li, Re (in molybdenite?), Sc, Sn, W, and Zn.
Cover thickness and description Uranium-fluorine mineralization occurred during late stages of protracted period of magmatism and in close association to rhyolite dikes (Cunningham and others, 2007). Potential magmatic connection suggests more potential exists beneath current exposure level.
Authors Albert H. Hofstra, Andrew Rupke, Joshua M. Rosera.
New data needs High-precision geochronology to tie magma processes to other mineralized volcanic systems in the region.
Geologic mapping and modeling needs Geologic map digitization.
Geophysical survey and modeling needs None requested at this time.
Digital elevation data needs Lidar complete for much of area; in progress over small western portion.