Cochetopa

Region West, Rocky Mountains
States
Mineral systems
Deposit types
Commodities
Other minerals

Information leading to the delineation of this focus area

Basis for focus area The focus area includes uranium occurrences in the Cochetopa mining district (Chenoweth, 1980; Nelson-Moore and others, 1978).
Identified resources Historical production of uranium.
Production The Los Ochos mine produced about 1.25 million lbs U3O8 between 1976 and 1981 (Pool, 2017). Prior to 1971, the Los Ochos Group produced 448,685 tons of ore at 0.14% U3O8 producing 1,253,513 lbs U3O8 (Nelson-Moore and others, 1978).
Status Past mining.
Estimated resources No data.
Geologic maps Lipman (2012), scale 1:50,000; Olson (1976a, b), scale 1:24,000; Olson and Steven (1976), scale 1:24,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Jurassic Junction Creek Sandstone and Morrison Formation; faults where the Morrison Formation has been faulted against Precambrian granite and schists, altered Precambrian rocks along a fault, fault breccia. As reported in Nelson-Moore and others (1978), deposits in this area are nearly vertical tabular bodies in brecciated and silicified Morrison sandstone and siltstone along the east-west-trending Los Ochos high-angle normal fault.
Deposits Los Ochos Group, Los Ochos mine (MRDS dep_id: 10190987), Thornburg mine (MRDS dep_id: 10013146), La Rue Claims, T-2 mine.
Evidence from mineral occurrences MRDS; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006).
Geochemical evidence Pitchblende is primary U mineral, occurring in veinlets and as coatings on marcasite grains. Autonite and uranophane are secondary minerals. Uranopilite, zippeite, and johannite formed as encrustations after exposure in Thornburg mine workings.
Geophysical evidence No data.
Evidence from other sources No data.
Comments Orebodies at the Los Ochos mine are in brecciated and silicified sandstones and mudstones of the Junction Creek and Morrison Formations and in Precambrian schist. The genesis of the deposits is unclear, but based on work by Olson (1988) who identified Oligocene volcanic rocks as the possible source of uranium a tentative assignment of Volcanic-related Structure-bound model is assigned to this area. Beryllium and Li inferred from the mineral system/deposit type table (Hofstra and Kreiner, 2020).
Cover thickness and description Unknown.
Authors Susan Hall, Michael K. O'Keeffe.
New data needs Geophysics, complete lidar.
Geologic mapping and modeling needs Mapping at 1:24,000 scale complete.
Geophysical survey and modeling needs High resolution Rank 1 aeromagnetic and aeroradiometric surveys needed.
Digital elevation data needs Lidar in progress over much of the focus area; complete in very northern portion.