Unnamed (east of lower Spaulding Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag
Other commodities Au; Cr
Ore minerals magnesiochromite; pyrite
Gangue minerals clay minerals; silica-carbonate minerals

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale D-2
Latitude 62.93449
Longitude -156.51302
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on a northeast-trending ridge east of Spaulding Creek, at an elevation of 550 meters. It is in the NE1/4 SE1/4, section 20, T. 33 N., R. 38 W., of the Seward Meridian. The location is accurate (T.K. Bundtzen, unpub. field data, 1979).

Geologic setting

Geologic description

This occurrence is in a N60E-trending, mafic to intermediate dike or sill about 30 feet thick. The dike or sill intrudes the shale and sandstone of the Upper Cretaceous, Kuskokwim Group. The dike has been extensively altered to silica-carbonate rock in breccia zones up to 10 feet wide at the contacts of the dike and the sedimentary rocks. Shear zones in adjacent sandstone are pyritized (Bundtzen and Laird, 1982; Miller and Bundtzen, 1994; Miller, Bundtzen, and Gray, 2005). A grab sample of mineralized dike contained 0.16 ounce of silver per ton, 1,000 parts per million chromium, and 150 parts per billion gold (Bundtzen and Laird, 1982; Miller, Bundtzen, and Gray, 2005). A highly brecciated felsic dike thought to be an extension of the breccia unit at the Katz prospect (ID028) is exposed about 65 feet west of this occurrence.
Geologic map unit (-156.515385241554, 62.9338565077743)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization Undated; probably Late Cretaceous based on nearby dated intrusions along Ganes-Yankee Creek fault (Bundtzen and Miller, 1997).
Alteration of deposit Extensive silica-carbonate alteration of a intermediate to mafic dike; sericitic alteration in felsic dike.

Production and reserves

Workings or exploration Three prospect pits about 50 feet apart expose the altered dike.
Indication of production None

References