PMRGX-5

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu
Other commodities Mo; Pb; Zn
Ore minerals chalcopyrite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale PM
Quadrangle map, 1:63,360-scale A-6
Latitude 55.181
Longitude -161.82
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence, located on the northern tip of Dolgoi Island, represents a 6,000- by 3,000-foot color anomaly (Christie, 1974, anomaly 66; Wilson and others, 1988, locality 54). The map site is 1,500 feet north of hill 950, near the center of the anomaly. The site is referred to as PMRGX-5 by Wilson and others (1988).

Geologic setting

Geologic description

Christie (1974) described a 6,000- by 3,000-foot color anomaly, elongate east-west and truncated at the coast on the north. Rocks in the area of the anomaly consist of altered granodiorite and diorite porphyry that intrude volcaniclastic rocks of the Oligocene to Miocene Belkofski Formation (Wilson and others, 1988). Abundant sulfides, including chalcopyrite and pyrite, are present, especially near the contact with the diorite porphyry. Moderate fracturing is widespread. Alteration minerals include chlorite, epidote, and fine-grained sericite.
Christie collected three soil or silt samples containing as much as 0.04 ppm gold, 2.3 ppm silver, 151 ppm zinc, 575 ppm copper and 11 ppm molybdenum. Samples collected by the U.S. Geological Survey were anomalous in copper, lead, and zinc (Wilson and others, 1988).
Geologic map unit (-161.822004166228, 55.1801445299719)
Mineral deposit model Porphyry Cu, Porphyry Cu-Mo, Porphyry Cu-Au (Cox and Singer, 1986; models 17, 21a, 20c)
Mineral deposit model number 17, 21a, 20c
Age of mineralization Oligocene or younger.
Alteration of deposit Christie (1974) noted the presence of epidote, chlorite, and fine-grained sericite.

Production and reserves

Workings or exploration During his brief reconnaissance, Christie (1974) collected three silt or soil samples that contained as much as 0.04 ppm gold, 2.3 ppm silver, 151 ppm zinc, 575 ppm copper, and 11 ppm molybdenum. Rock samples 84AAi79 and 84AJm715, collected by the U.S. Geological Survey in the mid-1980s, were anomalous in copper, lead, and zinc (Wilson and others, 1988).
Indication of production None

Additional comments

This site is located on land patented by, or interim-conveyed to, the Aleut Corporation.

References