Unnamed (east of Dishna River)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Mn
Ore minerals pyrolusite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale C-3
Latitude 62.7344
Longitude -157.31302
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the summit of a north-trending ridge about 5 miles east of the Dishna River and 0.7 mile southeast of hill 1335. It is at an elevation of about 1,500 feet, about 0.2 mile east of the center of section 34, T. 31 N., R. 43 W., of the Seward Meridian. The location is accurate.

Geologic setting

Geologic description

This occurrence is a pyrolusite-quartz vein in breccia that cuts shale and sandstone of the Upper Cretaceous, Kuskokwim Group, near an altered mafic dike (Miller and Bundtzen, 1994; Miller, Bundtzen, and Gray, 2005). One sample of semi-massive pyrolusite in a brecciated quartz vein contained 1.58 percent manganese (Bundtzen, Laird, and Lockwood, 1988). The amount of pyrolusite in the sample suggests that the analysis understates the manganese content of the occurrence.
Geologic map unit (-157.315381551735, 62.7337272386812)
Mineral deposit model Pyrolusite in quartz vein.
Age of mineralization Younger than the Upper Cretaceous host rock.
Alteration of deposit Mafic dike is altered to silica and carbonate minerals.

Production and reserves

Workings or exploration The Alaska Division of Geological and Geophysical Surveys sampled this occurrence in 1983 (Bundtzen, Laird, and Lockwood, 1988).
Indication of production None