Big Onion

Porphyry copper (Cu-Au) deposit in British Columbia, Canada

Names and other identifiers

GMRAP ID 9639
Alternate names Big Onion, Larsen
Tract name Intermontane Island-Arc Cu-Au (003pCu2002x)
Group name Afton-Ajax Group
Included sites Group includes Afton, Ajax JV, Big Onion, DM-Audra-Crescent, Galaxy, Iron Mask, and Rainbow deposits and Ace, Admiral Dewy, Crescent, Fargo, Kimberly, and Python prospects.
Site status deposit

Geographic location

Country Canada
State or province British Columbia
Geographic location -120.436715385, 50.662805988
Geologic map unit -120.436715385, 50.662805988
Nearby data

Geologic information

Deposit type Porphyry copper
Deposit subtype Cu-Au
Age (Ma) 205Ma
Age determination method U-Pb zircon
Age range 205 Ma
Age reference unknown
Minerals bornite, chalcopyrite, magnetite, pyrite
Associated rocks diorite, picrite, diorite breccia, monzonite
Tectonic setting island arc
Stratigraphic age Late Triassic

Commodity and development information

Development status Prospect
Major commodities Cu, Au
Tonnage (Mt) 3Mt
Cu grade (%) 0.71%
Au grade (g/t) 0.44g/t
Contained copper 23,000t
Gold-Moly ratio -9999

Reference information

Study area name British Columbia and Yukon Territory
References MINFILE BC (2009); Sinclair (2007)
Site reference Mihalasky and others (2011, revised 2013)
MINFILE BC, 2009, MINFILE Mineral inventory: British Columbia Ministry of Energy, Mines and Petroleum Resources, MINFILE database, total records 12,523, accessed December 2009, at http://minfile.gov.bc.ca/.
Sinclair, W.D., 2007, Porphyry Deposits, in Goodfellow, W.D., ed., Mineral deposits of Canada—A synthesis of major deposit-types, district metallogeny, the evolution of geological provinces, and exploration methods: Geological Association of Canada, Mineral Deposits Division, Special Publication no. 5, p. 223–243.