Hot Air Bench (Columbia Mine)

Mine, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag
Ore minerals arsenopyrite; gold

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale C-1
Latitude 64.5988
Longitude -165.4079
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Hot Air Bench placer is on the north side of lower Glacier Creek. The coordinates are for the approximate midpoint of an open-cut mine 900 feet north-northwest of the mouth of Snow Gulch on the Columbia claim of the Hot Air Mining Company (U.S. Mineral Survey No. 403). The bench placer trends west-southwest, subparallel to Glacier Creek. It is included in locality 101 of Cobb (1972 [MF 463], 1978 [OFR 78-93]). Hummel's (1962 [MF 247]) locality 7 is incorrect. The map location is in the NE1/4 section 26, T. 10 S., R. 34 W., Kateel River Meridian, and it is accurate to within 250 feet.

Geologic setting

Geologic description

The Hot Air Bench appears to be a true bench of Glacier Creek. It is approximately 100 feet vertically above and 900 feet horizontally north of Glacier Creek. Two claims of the Hot Air Mining Company were located May 28, 1899, and August 17, 1900; the claims were patented in 1902 (U.S. Mineral Survey No. 403). Apparently the bench channel was very well defined for about 400 to 500 feet. According to Collier and others (1908, p. 193-194), who were in the area in 1903, the channel was about 100 feet wide and had well-defined bedrock rims. The channel gravels were at a depth of about 20 feet. Pay gravels, largely of schist and marble, were about 4 to 5 feet thick and rested on chloritic schist bedrock. Gold was described as similar to that in Glacier Creek (NM220): fine, bright, and well rounded. The well-defined channel apparently played out to the west and turned toward Glacier Creek to the east. Moffit (1913, p. 85-86) reported veins as much as 6 inches thick in bedrock below the channel in the direction of Snow Gulch. He proposed that the source of the placer gold was local. Cathcart (1922, p. 243), in contrast, did not believe the gold was local, a conclusion that appears borne out by the character of the gold reported by Collier and others (1908). Cathcart (1922) also reported that the schist contained arsenopyrite.
The Hot Air Bench was extremely rich. Historic photographs show rows of gold bars cast from Hot Air gold. Collier and others (1908) reported that the production was 'not less than $600,000' (about 30,000 ounces of gold) and that pay in the best part of the channel ran about 2.5 ounces of gold per cubic yard. Assuming the fairly common 900 fineness value of placer gold in this area, the placer also produced about 3,000 ounces of silver. Collier and others (1908) also reported that placer gold was found higher on the slopes, a report consistent with the later discovery of the Ullrich placer (NM218) above and upstream of Hot Air Bench.
Geologic map unit (-165.41050572015, 64.5980345735356)
Mineral deposit model Alluvial placer Au; elevated bench formed on ancestral Glacier Creek (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Pleistocene.

Production and reserves

Workings or exploration The first bench claims were located in 1899; mining commenced immediately. The claims were surveyed for patent in 1901, at which time there was a small open cut on the Columbia claim. The richest part of the placer was mined by 1903, when the area was visited by Collier and others (1908). The deposit was mainly mined hydraulically; gold was recovered in a narrow sluice set in the downstream section towards Glacier Creek.
Indication of production Yes
Production notes Total production is believed to have been at least 600,000 dollars (gold at 20.67 dollars per ounce) or about 30,000 ounces of gold and 3,000 ounces of silver.