Unnamed Occurrence (ARDF - WI058; headwaters of Malamute Fork John River), Koyukuk Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - WI058; headwaters of Malamute Fork John River)	- not defined -
Koyukuk Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is located along a southwest-flowing headwater tributary to the Malamute Fork, John River. It is about 4.5 miles southwest of the junction of Midas and Sixtymile Creeks. The occurrence is at an elevation of about 1,650 feet on the tributary, in the NE1/4 section 25, T. 29 N., R. 22 W., of the Fairbanks Meridian. The occurrence is the site of sample 519 in Dillon and others (1981 [AOF 133B]). The location is accurate within one-half mile.
Geology: Two sources report Cu and Pb mineralization here. Dillon and others (1981, plate 1 [AOF 133B]) note a small area of Cu-Pb mineralization. Grybeck (1977, locality. 31) reports an occurrence of stratiform Cu, Pb, and Zn mineralization approximately 1.5 miles southeast of the site shown by Dillon and others. These two mineral occurrences may be the same. At sample locality 519 of Dillon and others (1981 [AOF 133B]), quartzite layers in marble and calcareous contains massive arsenopyrite and pyrite. These sulfides occur in bands that are parallel to the enclosing strata and are up to 10 cm thick and 20 m long. A sample contains 500 ppm arsenic, 219 ppb antimony, and 23% iron. Similar occurrences occur along strike for up to 1 km. Grybeck (1977), citing unpublished industry data, reports pyrrhotite, galena, sphalerite, and chalcopyrite in interbedded schist, quartzite, and limestone. The rocks in the area consist of Devonian, Skajit Limestone and Middle to Upper Devonian black calcareous schist and dark limestone (Dillon and others, 1986).
Workings: Eight prospecting sites were located in the area in 1976 (Grybeck, 1977).

Commodities (Major) - Cu, Pb, Zn; (Minor) - As, Sb
Development Status: None
Deposit Model: Polymetallic replacement deposit (?) (Cox and Singer, 1986; model 19a)

Other Databases

Link to USGS - Alaska:	WI058

Other Regions, Features and Areas containing this locality

References