Geologic descriptionAt this prospect, pyrite and chalcopyrite are disseminated in a small diorite stock and surrounding hornfels (Richter and others, 1975). The sulfide-bearing rocks are limonite stained and also locally contain abundant copper-staining along fractures (Richter and Matson, 1970 ([OFR 70-275]). Richter and others (1975) estimate that the area of hydrothermal alteration in diorite and hornfels is about 300 by 300 feet in size. The average grade of surface samples is about 0.15 percent copper and less than 0.01 percent molybdenum. A grab sample of copper-stained diorite and a grab sample representing 500 feet of pyrite-bearing argillite talus respectively contained 0.2 parts per million (ppm) and 0.04 ppm gold (Richter and Matson, 1970 [OFR 70-275]). The deposit has been estimated to contain 8 million tons with an average grade of 0.20 percent copper and very low amounts of molybdenum (Richter and others, 1975). The host diorite is inferred to be Cretaceous in age; it intrudes Jurassic or Cretaceous siliciclastic rocks (Richter and Jones, 1973). |
| Geologic map unit |
(-141.629437568137, 62.1092565391914) |
| Mineral deposit model |
Porphyry Cu-Mo (Cox and Singer, 1986; model 21a) |
| Mineral deposit model number |
21a |
| Age of mineralization |
Cretaceous? The age of the host diorite is inferred to be Cretaceous (Richter and Jones, 1973). |
| Alteration of deposit |
Quartz-pyrite (+/- sericite?) veining and replacement; oxidation has resulted in iron- and copper-staining. |
