Black Hawk Mining District

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

Information leading to the delineation of this focus area

Basis for focus area Productive vein traces; Black Hawk district boundary (McLemore, 2017).
Identified resources Historical production of copper, fluorite, gold, silver, and tungsten.
Production Silver, Au, Cu, Pb, F (615 tons); W produced from 1881-1893; W production: 10,542 lbs of 2.7-7.7% WO3. Recurrent exploration work in 1917 and some exploration focused on U, Ni, and Co from 1949-1952; additional exploration 2010 to present (production data from
Status Past mining. Past producers purchased by Sante Fe Gold Corp. on April 3, 2019; current exploration.
Estimated resources Possibly 1,000 short tons ore remains in the faces as Black Hawk, Alhambra, and Rose mines closed in 1893 (production data in McLemore, 2017).
Geologic maps Gillerman and Whitebread (1956, plate 14), scale 1:8,100; Hedlund (1978b), scale 1:24,000; Drewes and others (1985), scale 1:250,000.
Geophysical data Adequate but unpublished aeromagnetic and radiometric coverage. The area is entirely covered by aeromagnetic and aeroradiometric coverage collected on a 1000-foot grid, so Rank 1, but the coverage is unpublished. USGS can study it, but can't publish the coverage, only a map derived from it, and cannot give coverage to the states. Other than that, inadequate coverage.
Favorable rocks and structures Fissure veins that pinch and swell along strike with steep dip, and northerly to easterly strike. Precambrian quartz diorite gneiss is a preferred host rock.
Deposits Black Hawk mine (MRDS dep_id: 10067835; USMIN Site_ID: NM00041), Alhambra mine (MRDS dep_id: 10101798), Rose mine (MRDS dep_id: 10013296), Silver King (Hobson) mine (MRDS dep_id: 10097907), Good Hope mine (MRDS dep_id: 10014643).
Evidence from mineral occurrences MRDS; USMIN; McLemore (2017).
Geochemical evidence Very limited dump-, select-, grab-sampling from Gillerman and Whitebread (1956, p. 301) gave mean values from 5 ore samples (only 3 analyzed for U3O8) of 0.153% U3O8, 1.28% Ni, 0.23% Co, and 13.06 oz/st Ag.
Geophysical evidence All of the focus area is covered by aeromagnetics and aeroradiometric data collected on a 1,000-foot grid, so Rank-1, but the data are unpublished. Also available are NURE data with 3-mile line spacing.
Evidence from other sources New Mexico Mining and Minerals Division mine permits.
Comments Fluid inclusion studies of Gerwe (1986) and Gerwe and Norman (1984) yielded results consistent with other Five-element Vein-type systems. Temperatures (homogenization) were relatively high from 189 to 404 degrees Celsius with scattered high salinities among dominant more dilute results.
Cover thickness and description Veins were discovered in outcrop.
Authors Timothy S. Hayes, Lukas Zurcher, Virginia T. McLemore.
New data needs Ground EM surveying on a tight grid (100-m, perhaps) would directly target ore shoots within 16 additional mapped "silver, nickel, or cobalt-bearing veins" from Gillerman and Whitebread (1956, Plate 14). Geochemical studies are needed of the ore and host rock.
Geologic mapping and modeling needs Hedlund maps excellent, but need digitizing.
Geophysical survey and modeling needs Geophysics needed to make better assessment and to help industry.
Digital elevation data needs Probably needs lidar coverage.