Heddleston

Porphyry copper deposit in Montana, United States

Names and other identifiers

GMRAP ID 22
Tract name Northern Rocky Mountains (003pCu9004)
Site status deposit

Geographic location

Country United States
State or province Montana
Geographic location -112.36, 47.025833333
Geologic map unit -112.36, 47.025833333
Nearby data

Geologic information

Deposit type Porphyry copper
Age (Ma) 46Ma
Age determination method unknown
Age range 46 Ma
Age reference Singer and others (2008)
Minerals bornite, carbonate, chalcocite, chalcopyrite, clay minerals, covellite, galena, marcasite, molybdenite, pyrite, pyrrhotite, rhodochrosite, sericite, sphalerite, tetrahedrite/tennantite
Associated rocks breccia, quartz monzonite porphyry, quartz porphyry, argillite, diorite, gabbro, quartzite
Tectonic setting continental margin
Stratigraphic age Eocene

Commodity and development information

Development status Occurrence
Major commodities Cu
Tonnage (Mt) 302Mt
Cu grade (%) 0.36%
Mo grade (%) 0.005%
Au grade (g/t) 0.053g/t
Ag grade (g/t) 5.2g/t
Contained copper 1,100,000t
Gold-Moly ratio 10

Reference information

Study area name United States
References Long (1992); McKee (1978); McClernan (1983); Miller and others (1973); Singer and others (2008)
Site reference U.S. Geological Survey National Mineral Resource Assessment Team (2002)
Long, K.R., 1992, Reserves and production data for selected ore deposits in the United States found in the files of the Anaconda Copper Company: U.S. Geological Survey Open-File Report 92-002, 21 p. (Also available at http://pubs.usgs.gov/of/1992/0002/report.pdf.)
McClernan, H.G., 1983, Metallic mineral deposits of Lewis and Clark County, Montana: Butte, Montana Bureau of Mines and Geology Memoir 52, 73 p.
McKee, J., 1978, Petrology, alteration, and mineralization of the Poorman Creek-Silver Bell stock porphyry Cu-Mo deposit [abs.]: Geological Society of America Abstracts with Programs, v. 10, no. 5, p. 234.
Miller, R.N., Shea, E.P., Goddard, C.C., Jr., Potter, C.W., and Brox, G.B., 1973, Geology of the Heddleston copper-molybdenum deposit, Lewis and Clark County, Montana, in Pacific Northwest Metals and Minerals Conference, Coeur d’Alene, Idaho, 1973, Proceedings: American Institute of Mining and Metallurgical Engineers, p. 1–33.
Singer, D.A., Berger, V.I., and Moring, B.C., 2008, Porphyry copper deposits of the world—Database and grade and tonnage models, 2008: U.S. Geological Survey Open-File Report 2008-1155, [45] p. and digital data, accessed December 31, 2013, at http://pubs.usgs.gov/of/2008/1155/.