Unnamed Occurrence (ARDF - SD022; on upper Powers Creek), Petersburg Mining District, Hoonah-Angoon Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - SD022; on upper Powers Creek)	- not defined -
Petersburg Mining District	Mining District
Hoonah-Angoon Census Area	Census Area
Alaska	State
USA	Country

The occurrence is in the Tracy Arm-Fords Terror Wilderness Area which is closed to mineral exploration and mining.
Location: This altered zone is at an elevation of about 800 feet, about 0.4 mile southwest of the terminus of the Sumdum Glacier. It is about 0.5 mile north-northeast of the center of section 30, T. 47 S., R. 74 E.
Geology: This occurrence is an zone of rusty, siliceous, chlorite schist that is southwest of the toe of the Sumdum Glacier; Brew and Grybeck (1984) assign the schist a Cretaceous metamorphic age. Kimble and others (1984) systematically sampled the zone with a series of 11 samples that extended for 1,150 feet perpendicular to the layering of the metamorphic rocks. All 11 samples contained 0.5 to 1.0 part per million (ppm) silver; 3 contained 15-30 ppm molybdenum, and 2 contained 150-380 ppm zinc. Many of the rocks in the iron-stained zone have sparse disseminated sulfides. The sulfides are mainly pyrrhotite although trace chalcopyrite also occurs. The iron staining is probably due to the weathering of the pyrrhotite.
Workings: None beyond sampling by government geologists.
Age: Occurs in schist of Cretaceous (metamorphic) age.
Alteration: Iron-staining probably due to weathering of pyrrhotite.

Commodities (Major) - Ag; (Minor) - Mo, Zn
Development Status: None
Deposit Model: Sparse pyrrhotite and rare chalcopyrite in gneiss.

Other Databases

Link to USGS - Alaska:	SD022

Other Regions, Features and Areas containing this locality

References