Structure: Abundant Normal Faults Vein Offset By Rhyolite Dike

Alteration: Silicification

Deposit: Vein is parallel to delamar vein. Vein is offset by a late rhyolite dike. Ore is silicified quartzite breccia and veinlets of comb quartz. This conspicuous silicified rib outcrops boldly along ridgecrest adjacent to workings. Raise above adit explores the vein and exposes a 2-3 ft wide zone which is iron stained and shows subparallel sets of quartz veins which cut a highly siliceous quartzite breccia. On close examination, the vein outcrop consists of an iron-stained quartzite breccia cemented with jaspery silica or more massive vitreous cockade or comb quartz. Some wider, massive, late-stage quartz veins crosscut breccia parallel to vein outcrop. Upper workings are a fairly continuous line of shafts and stopes often inclined to the west along dip of the vein. The vein outcrops boldly adjacent to and west of workings and continues upslope for several hundred feet. The sampled stope trends n10-20e and dips 75 n W along vein. At S end of stope, the vein outcrop consists of pink angular quartzite fragments cemented by comb and drusy quartz. Prismatic quartz encrusts vugs As do fine crystals of late-stage jarosite. Dark bands in the quartz are very fine-grained sulfides of which the only recognizable mineral is pyrite. Fe and Mn oxides are common. Part of the vein consists of fractured quartzite, and malachite is deposited along fine fracture surfaces in the quartzite and also in the vein material. Several samples of quartz vein in outcrop and on dump contain coarse clots of tetrahedrite (mostly oxidized to cu oxides) and abundant oxidized and unoxidized pyrite.

Development: Captain delamar purchased a part interest in the mine in 1893. In 1897 it was equipped with a 10-stamp mill. In 1932-1933, the mcguffie and gentry lease on the april fool produced considerable shipping ore. The horn brothers of delamar were doing a little mining and development work and shipping some ore in 1931. The mine employed 35 men in 1899, at which time there was extensive mine exploration ongoing. The april fool was among the mines consolidated under bamberger-delamar mines co in 1902. 1983 examination indicated backhoe trenching of dumps and sorting of material near workings done 1-2 years ago.

Geology: Ore body is a fissure vein. Main ore shoots are narrow veins less than 10 feet wide, divided into lenses by intersecting gouge seams, continuing for a length of 1500 feet. The vein contains masses of breccia with cherty quartz cement, and veinlets of crustified and banded "comb" quartz. The april fool vein is mineralized to a variable extent for length of 3,000 feet, at depth of 700 feet. It is roughly parallel to and 500 to 700 feet east of the delamar vein

Rock formation(s): Prospect Mountain Quartzite


Ore(s): Quartzite Breccia In Fissure Zone

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Link to USGS MRDS:	10037386

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References