Boriana Mines (Tungsten Mine), Boriana Canyon, Boriana Mining District, Hualapai Mountains, Mohave County, Arizona, USAi

Regional Level Types
Boriana Mines (Tungsten Mine)	Group of Mines
Boriana Canyon	Canyon
Boriana Mining District	Mining District
Hualapai Mountains	Mountain Range
Mohave County	County
Arizona	State
USA	Country

A W-Cu-Ag-Au occurrence/mine located in secs. 7, 9, 18, T18N, R15N, & sec. 12, T18N, R16W, G&SRM, in Boriana Canyon and Bull Canyon, 3 miles SE of Wabayuma Peak and 21 km ENE of Yucca at about 5,000 feet of altitude. Discovered prior to 1908. Comprised of 40 unpatented claims. The first year of production was 1915 and the last was 1980. Production years included a period prior to 1918 to 1943, 1951-1957, and 1979-1980. Owned and operated by the Molybdenum Corporation of America (1937-1943). Owned by the Boriana Mining Company (1982-).

Mineralization is a W deposit hosted in schist. The ore body is a pinch & swell body that strikes N35E and dips 80SE at a width of 4.57 meters and a length of 518.16 meters and with a depth-to-top of 0 meters and a depth-to-bottom of 323.09 meters. Wolframite-scheelite bearing quartz veins cut by sericite veinlets occur in fine-grained muscovite schist, mainly in 2 composite lodes of quartz veins 90 to 135 feet apart (East lode and West lode). Each vein is comprised of 2 to 10, or even 20, parallel quartz veins and stringers, separated by schist, within widths of a few feet to 20 feet or more. At least 4 of the composite lodes have been encountered within a width of 200 feet. The vein system strikes N30 to 40E, conforming to foliation of the schist, and dips vertically to 75SE. Ore is in the fractures. Country rock is a belt of schist, locally ¼ to ½ mile wide, that strikes N30 to 40E, and dips as the veins, and extends for several miles across the range. In the vicinity of the mine, the schist is a thinly laminated to blocky gray slate with some sandy phases; abundant fine-grained sericite and chlorite mark its parting planes. The schist belt is intruded on both sides by coarse-grained biotite granite which grades into gneiss near its contacts. Dikes of aplite and pegmatite cut both the gneiss and the schist. Local alteration includes silicification & sericitization. The ore-bearing veins appear to have originated in the granite intrusive at the north end of the vein zone. The richer veins occur in areas where the phyllite is softer, while the veins are more narrow and lean in areas with hard and blocky phyllite. Ore control is attributed to foliation in the phyllite and certain joint planes in granite; fracturing; and lithology. Minor faulting offsets the veins.

The deposit was known prior to 1908 and produced comparatively little until 1915, thereafter production increased until it was Arizona's leading tungsten producer in 1918 and again, during 1933-1937 it was the leading producer in Arizona and probably the second largest producer in the USA. Also operated 1951-1957 and 1979-1980.

Workings include surface and underground openings with a length of 4,724.4 meters and an overall depth of 323.09 meters. They were 1,100 feet deep and included 9 levels plus 3 sub-levels and more than 15,500 feet of drifts. The 5th level was the main haulage adit. There is 1 inside winze sunk vertically to 450 feet with 3 levels in this winze with about 5,000 feet of workings. The cut and fill mining method was most commonly employed. The principal ore shoot on the West lode had been mined from surface to the 7th. level by June 15, 1941, with a stope length of 8,700 feet; similarly, on the East lode, an ore shoot with a stope length of 1,000 to 1,100 feet had been mined from above the 3rd. level to the 7th. level.

The maximum annual output of 26,299 units was made in 1936. After 1930, small amounts of Cu concentrates were also recovered. In 1918, Boriana was the largest W producer in Arizona. The mine produced 98% of 120,413 short ton units of WO3, which equals 2,400,000 pounds of WO3. The Boriana Mine had yielded to the end of 1956 far more W minerals than the combined output from the rest of the state and also had much larger inferred reserves.

Reserve-resource data: Type: In-situ (estimate year = 1943): indicated reserves: 4,399,000 metric tons @ 1 weight percent.

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