Porphyry copper prospect in Alaska, United States

Names and other identifiers

Alternate names Unnamed (southeast of mouth of Stag Bay); Stag Bay copper
Tract name Southeast Alaska Tertiary (003pCu5005)
Site status prospect

Geographic location

Country United States
State or province Alaska
Geographic location -136.3477, 57.9119
Geologic map unit -136.3477, 57.9119
Nearby data

Geologic information

Deposit type Porphyry copper
Age determination method Geologic inference
Age range Cretaceous or younger
Age reference Johnson and Karl (1985)
Minerals chalcopyrite, magnetite, pyrite
Tectonic setting continental margin
Stratigraphic age Cretaceous or younger

Commodity and development information

Development status Prospect
Major commodities Cu, Fe
Minor commodities Ag
Gold-Moly ratio -9999

Reference information

Comments Johnson and Karl (1985) mapped rocks in the area as Freeburn assemblage, a collage of kilometer-scale, fault-bounded, lozenge-shaped blocks of Cretaceous- and Cretaceous(?)-age metasedimentary and metavolcanic rocks. At contact between andesite and diorite. Sheared and altered, fine-grained gabbro or diorite containing magnetite, pyrite, and chalcopyrite. Two trenches expose 55 and 35 ft of mineralized rock that consists of about 60 percent magnetite and up to 2 percent chalcopyrite.
Study area name United States
References U.S. Geological Survey (2014a); Johnson and Karl (1985)
Site reference U.S. Geological Survey National Mineral Resource Assessment Team (2002)