Soil sampling in the area of this site revealed small stibnite deposits beneath muskeg swamp (Sainsbury, 1957).

Location: The approximate location of this mine is at an elevation of about 200 feet, about 1.4 miles north-northwest of Caamano Point. The site is in section 26, T. 73 S., R. 88 E., of the Copper River Meridian. It corresponds to loc. 40 in Elliott and others (1978). The location is accurate within about 0.2 mile.

Geology: The country rocks near this site are Silurian or Ordovician andesitic and basaltic tuff and agglomerate, and minor interbedded graywacke, argillite, and limestone (Brew, 1996, p. 27, 29). The strata were regionally metamorphosed to greenschist-grade phylliteand semischist in Late Cretaceous time. Their early Paleozoic premetamorphic age assignment is based on a Silurian or Ordovician Pb-U (zircon) isotopic age of a dike that intrudes the bedded rocks. The deposit consists of stibnite-bearing fissure veins and irregular replacement masses of stibnite in brecciated and partly dolomitized and silicified limestone (Sainsbury, 1957, p. 163-178; Cobb and Elliott, 1980, p. 23; Maas and others, 1995, p. 277). The limestone is interbedded with gray, calcareous slate and phyllite. The contact between the limestone and phyllite country rocks strikes NW and dips about 30 NE. At the prospect, the country rocks are intricately veined with quartz and calcite stringers, and contain abundant disseminated pyrite. The largest stibnite vein is 3.5 feet thick and about 90 feet long, and consists almost entirely of massive stibnite of radiating acicular and platy crystal habits. The crystals show evidence of mild deformation. Small amounts of realgar and kermesite also are reported at the prospect. A small, highly altered dike that crops out east of the main antimony deposit, contains pyrite, and, reportedly, a little gold. The veins and associated alteration postdate the Late Cretaceous penetrative metamorphic fabric of the hostrocks. The relatively mild deformation of the stibnite is undated, but it probably postdates, or occurred during a late phase of, the Upper Cretaceous regional metamorphism.

Workings: The deposit was discovered in 1914. Exploration before 1952 included a 15-foot shaft, a 44-foot shaft, drifts totalling 100 feet, and several trenches (Sainsbury, 1957). Maas and others (1995, p. 277) report a third shaft, of unknown length. Samples across about 3 feet of the main vein contained 25.67-48.86% Sb, and a shipment of 956 kg of hand-sorted rock from the trenches assayed 44.8% Sb, 12.6% S, 0.5% As, and 14.8% insolubles (Maas and others, 1995, p. 277). Samples of disseminated stibnite ore collected by the U.S. Geological Survey contained up to 10,000 ppm Sb (Sainsbury, 1957, p. 173). A sample of pyrite-rich quartz- and carbonate-veined phyllite and marble collected in 1975 by the U.S. Geological Survey on the coast about 1 mile north-northeast of Caamano Point contained up to 7.5 ppm Au, 2 ppm Ag, 1000 ppm Sb, and more than 1% As (Elliott and others, 1978, loc. 40; Koch and Elliott, 1978, USGS sample 75BG125 [OFR 78-156A]).

Age: Late Cretaceous or younger.

Alteration: The country rocks are silicified and dolomitized.

Production: Samples across about 3 feet of the main vein contained 25.67-48.86% Sb, and a shipment of 956 kg of hand-sorted rock from the trenches assayed 44.8% Sb, 12.6% S, 0.5% As, and 14.8% insolubles (Maas and others, 1995, p. 277).

Commodities (Major) - Sb; (Minor) - Au

Development Status: Yes; small

Deposit Model: Simple antimony deposit (Cox and Singer, 1986; model 27d)

Other Databases

Link to USGS - Alaska:	KC040

Other Regions, Features and Areas containing this locality

References