Hot Air

Mine, Undetermined

Alternative names

Hot Air No. 1

Commodities and mineralogy

Main commodities Sb
Other commodities Au
Ore minerals kermesite; pyrite; realgar; stibnite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale C-6
Latitude 55.518
Longitude -131.983
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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.

Geologic setting

Geologic description

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 phyllite and 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 host rocks. 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.
Geologic map unit (-131.984681759247, 55.5176383645256)
Mineral deposit model Simple antimony deposit (Cox and Singer, 1986; model 27d)
Mineral deposit model number 27d
Age of mineralization Late Cretaceous or younger.
Alteration of deposit The country rocks are silicified and dolomitized.

Production and reserves

Workings or exploration
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 percent Sb, and a shipment of 956 kg of hand-sorted rock from the trenches assayed 44.8 percent Sb, 12.6 percent S, 0.5 percent As, and 14.8 percent 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 percent As (Elliott and others, 1978, loc. 40; Koch and Elliott, 1978, USGS sample 75BG125 [OFR 78-156A]).
Indication of production Yes; small
Production notes 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).

Additional comments

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