Unnamed (west of Julian Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Sn
Other commodities As; Bi; Cd; Sb
Ore minerals arsenopyrite
Gangue minerals quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale A-3
Latitude 62.21865
Longitude -157.40405
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on hill 1390 on the spur that trends northwest between Spruce and Julian Creeks. It is about 0.6 mile northeast of the center of section 34, T. 25 N., R. 44 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

This occurrence consists of arsenopyrite-bearing quartz veinlets in a sericitically altered, granodiorite intrusion in flysch of the the Upper Cretaceous, Kuskokwim Group (Miller and Bundtzen, 1994; Bundtzen and Miller, 1997; Miller, Bundtzen, and Gray, 2005). The intrusion has a 40K/40Ar age of 70.1 Ma. The quartz veinlets occur in an area about 130 feet square. Grab samples of the veins contained up to 10.0 parts per million (ppm) silver, 100 ppm tin, more than 2,000 ppm arsenic, 11.0 ppm bismuth, 3.3 ppm cadmium, and 12 ppm antimony (McGimsey and others, 1988). The mineralized zone is a possible source of the placer gold in Julian (ID177) and Spruce (ID176) Creeks.
Geologic map unit (-157.406453269819, 62.2179568435702)
Mineral deposit model Sn-polymetallic deposit or Polymetallic vein (Cox and Singer, 1986; model 20b or 22c).
Mineral deposit model number 20b or 22c
Age of mineralization Unknown; the host intrusion has a 40K/40Ar age of 70.1 Ma (Miller and Bundtzen, 1994).
Alteration of deposit Sericitic alteration of granodiorite.

Production and reserves

Workings or exploration Samples were collected by the U.S. Geological Survey and Alaska Division of Geological and Geophysical Surveys in the 1980s (McGimsey and others, 1988).
Indication of production None