Unnamed

Occurrence, Inactive

Commodities and mineralogy

Main commodities Pb; Zn
Ore minerals galena; sphalerite
Gangue minerals pyrite

Geographic location

Quadrangle map, 1:250,000-scale SL
Quadrangle map, 1:63,360-scale C-5
Latitude 63.53
Longitude -171.04
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is in the headwaters of an unnamed stream that flows north to a lagoon on the northwest coast of St. Lawrence Island. The mouth of this stream is about 4 1/4 miles southwest of Kangee Camp and 7 miles southeast of Apatiki Camp on the island's northwest coast. The site is about 2 miles upstream of the mouth and is located within 1/2 mile. It is locality 14 of Cobb (1972) and Cobb (1980) summarized relevant references under the name 'Unnamed occurrence'.

Geologic setting

Geologic description

Thermally metamorphosed marble, cut by sulfide stringers containing galena, sphalerite, and pyrite, is exposed in the streambed (Patton and Csejtey, 1971, p. 15). Two samples of sulfide-bearing marble contained (1) 15 ppm silver, 15 ppm copper, greater than 2% lead, and 200 ppm zinc, and (2) 70 ppm silver, 700 ppm copper, greater than 2% lead, and greater than 1% zinc (Patton and Csejtey, 1971, p. C8). The marble is in the contact zone of the Taphook pluton with Mississippian limestone (Patton and Csejtey, 1980). The Taphook pluton is a composite intrusion that in this area is hornblende quartz monzonite. This pluton has not been dated but it is similar to the Sevuokuk pluton on the west coast of St. Lawrence Island that has a K/Ar age of 108 +/- 3.2 Ma (Patton and Csejtey, 1980).
Geologic map unit (-171.042752676988, 63.5290896092947)
Mineral deposit model Zn-Pb skarn? (Cox and Singer, 1986; model 18c?).
Mineral deposit model number 18c?
Age of mineralization Mid-Cretaceous; the marble is in the contact zone of the Taphook pluton with Mississippian limestone (Patton and Csejtey, 1980). This pluton has not been dated but it is similar to the Sevuokuk pluton on the west coast of St. Lawrence Island that has a K/Ar age of 108 +/- 3.2 Ma (Patton and Csejtey, 1980).
Alteration of deposit Thermal metamorphism of Mississippian limestone has commonly developed coarse marble on St. Lawrence Island (Patton and Csejtey, 1980) but calc-silicate minerals or tactite have not been described.

Production and reserves

Workings or exploration Two samples of sulfide-bearing marble contained (1) 15 ppm silver, 15 ppm copper, greater than 2% lead, and 200 ppm zinc, and (2) 70 ppm silver, 700 ppm copper, greater than 2% lead, and greater than 1% zinc (Patton and Csejtey, 1971, p. C8).
Indication of production None

References