Margaret

Porphyry copper deposit in Washington, United States

Names and other identifiers

GMRAP ID 23
Alternate names Earl
Tract name Cascade Arc (003pCu9014)
Site status deposit

Geographic location

Country United States
State or province Washington
Geographic location -122.080833333, 46.356388889
Geologic map unit -122.080833333, 46.356388889
Nearby data

Geologic information

Deposit type Porphyry copper
Age (Ma) 16Ma
Age determination method unknown
Age range 17–16 Ma
Age reference Singer and others (2008)
Minerals arsenopyrite, azurite/malachite, biotite, bornite, chalcopyrite, chlorite, chrysocolla, copper, covellite, epidote, galena, goethite/limonite, kaolinite, magnetite, molybdenite, pyrite, Sb-mineral, sericite, sphalerite, tourmaline
Associated rocks andesite dike, breccia, dacite dike, quartz porphyry dike, volcanic rocks, volcaniclastic rocks, granodiorite, quartz diorite, quartz monzonite
Tectonic setting continental margin
Stratigraphic age Miocene

Commodity and development information

Development status Occurrence
Major commodities Cu
Tonnage (Mt) 523Mt
Cu grade (%) 0.36%
Mo grade (%) 0.011%
Au grade (g/t) 0.24g/t
Ag grade (g/t) 1.6g/t
Contained copper 1,900,000t
Gold-Moly ratio 22

Reference information

Study area name United States
References Chaffee (1994); Derkey and others (1990); Lasmanis (1995); Singer and others (2008)
Site reference U.S. Geological Survey National Mineral Resource Assessment Team (2002)