Evening Star Mine (Maynard Mine; Bernice group; Bernice Mine; Rex Tin Mine; Standard District; Blue Grass), Kessler Peak, Ivanpah Mountains, Ivanpah Mining District, San Bernardino County, California, USAi

Regional Level Types
Evening Star Mine (Maynard Mine; Bernice group; Bernice Mine; Rex Tin Mine; Standard District; Blue Grass)	Mine
Kessler Peak	Peak
Ivanpah Mountains	Mountain Range
Ivanpah Mining District	Mining District
San Bernardino County	County
California	State
USA	Country

A former Cu-Au-Sn-W-Zn occurrence/mine located in secs. 24 & 25, T15N, R13E, SBM, about 5.3 km NNW of Kessler Peak, on the western margin of the Ivanpah Mountains, 4 km E of Cima Road and about 12 km S of Interstate 40 (8 miles N of Cima; 7½ miles S of Mountain Pass), on private land. This area is now in the Mojave National Preserve (wilderness area). Discovered about 1940. Produced during the periods 1939 to 1940 and 1942 to 1944. MRDS database stated accuracy for this location is 10 meters. Though previously prospected, tin ore was not discovered at the Evening Star Mine until 1940.

Mineralization is hosted in the Goodsprings dolomite close to the thrust contact with the Teutonia quartz monzonite. The ore body strikes N80W and dips 30S at a thickness of 28 meters, a width of 3 meters and a length of 28 meters. Ore body No. 1 is a pipe-like fissure vein and ore body No. 2 is an irregular replacement body. The primary mode of origin was hydrothermal activity and the secondary mode of origin was contact metasomatism. Primary ore control was fracturing. Wallrock alteration is slight (pyritization). The area of principal tungsten mineralization is along a sinuous granite-limestone contact exposed a quarter mile SE of the tin workings. Cu is from a Cu-bearing siliceous vein. Minerals reported from the mine are calcite, cassiterite, chalcopyrite, epidote, forsterite, magnetite, serpentine, scheelite, and tremolite. Most of these minerals are not well crystallized but well formed cassiterite crystals in excess of 1 cm have been recovered. Associated rocks include Late Cretaceous-Pennsylvanian granite. Local rocks include Carboniferous marine rocks, unit 2 (SE California Carbonate Assemblage) and/or Mesozoic granitic rocks, unit 3 (Sierra Nevada, Death Valley area, Northern Mojave Desert and Transverse Ranges).

Workings include surface and underground openings comprised of several shallow shafts and many surface cuts (1951). From 1940 through 1943 the mine was explored by two shafts and underground workings, plus a trench between the two shafts. An old, 340 foot adit was being extended but no contact had been reached by February, 1952.

Some tin ore was treated during the period 1942 to 1944 but no figures are available. In 1949, 50 tons of Cu-bearing, siliceous vein material stockpiled. At least one shipment of low-grade ore was made from the mine.

Analytical data results: Ore grade at 6.27% Sn.

Other Databases

Link to USGS MRDS:	10035358

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References