Unnamed (in Terra Cotta Mountains)

Occurrence, Inactive

Commodities and mineralogy

Main commodities As; Au; Sb; W
Other commodities Co
Ore minerals arsenopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MG
Quadrangle map, 1:63,360-scale A-1
Latitude 62.102
Longitude -153.394
Nearby scientific data Find additional scientific data near this location
Location and accuracy This unnamed occurrence is located in the Terra Cotta Mountains near the base of a northwesterly spur overlooking a north flowing, unnamed tributary of the South Fork of Kuskokwim River. It is at an elevation of 4,200 feet (1,280 m) in the NE1/4 sec. 12, T. 23 N., R. 23 W., of the Seward Meridian. The reporter visited the site in 1988; at station no. 88BT169.

Geologic setting

Geologic description

This unnamed occurrence is a quartz-sulfide vein swarm in altered dacitic tuffs of the Eocene, Terra Cotta Volcanic Field (Bundtzen, Harris, and Gilbert, 1997). Most of the material is in the form of talus and no exposures of the veins were observed. Some sulfide zones have been transformed into extensive gossan. The extent of the mineralized area was not measured. One sample contained 240 ppb gold, 2,200 ppm arsenic, 880 ppm tungsten, 110 ppm cobalt, and 200 ppm antimony (Bundtzen, Harris, and Gilbert, 1997).
Geologic map unit (-153.396231340527, 62.1013899150963)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Alteration of deposit Extensive ferricrete gossan.

Production and reserves

Workings or exploration The reporter sampled the site in 1988 during geologic mapping for the Alaska Division of Geological and Geophysical Surveys (Bundtzen, Harris, and Gilbert, 1997). One sample contained 240 ppb gold, 2,200 ppm arsenic, 880 ppm tungsten, 110 ppm cobalt, and 200 ppm antimony.
Indication of production None
Reserve estimates None.

References