Description:
Detailed Geologic map and cross sections of the Ramsay Mine Area, southeastern Plomosa Mountains, West-central Arizona. Report and two map sheets, scale 1:12,000, with cross-sections.
Locations of altered or mineralized rocks, mines and prospects are indicated on the geologic map, two examples below.
1. Black Mesa mine of Keith [1978] (same location as site # 11 of Richard [1992]). Tunnels and
shaft in brecciated fault zone between Redwall and Martin formations. Waste heap contains massive
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and comb-structured silica-FeOx vein material, as well as spongy quartz-limonite (after pyrite)
stockwork. Sparse malachite and chrysocolla fill open space in refractured silica-FeOx veins.
Brecciated quartz vein material with silica-FeOx cement also present. In shaft on SE side of canyon
mineralized breccia zones in carbonate are irregular and lenticular, with both steep and gentle dip.
Adjacent carbonate rocks show little evidence of alteration. Keith [1978] describes "spotty cerrusite,
anglesite, galena, chrysocolla, malachite, and brochantite,with siderite, quartz, ankerite, calcite and
limonite in lensing replacement deposits in steeply dipping Paleozoic limestone beds. Cellular boxwork
and vugs. Some native copper and cerargyrite". Available production data through 1981 indicate that
the ore produced contained about 11 % lead, 3.5% copper, 7 oz/ton of silver, and .2 oz/ton of gold
[Arizona Geologic Survey, unpublished data].
2. Shaft in fault, oriented 134/64 NE, between Redwall and Supai Formations. Massive, dense
silica-hematite in irregular clots along fault zone. Also earthy hematite along fractures. A few lenses of
sericitized Bolsa quartzite are present in the fault zone, otherwise alteration outside of fault zone is
minimal. (Same location as site #16 of Richard [1992])