Moghoweyik River

Occurrence, Inactive

Commodities and mineralogy

Main commodities Mo
Ore minerals molybdenite
Gangue minerals quartz; pyrite

Geographic location

Quadrangle map, 1:250,000-scale SL
Quadrangle map, 1:63,360-scale C-6
Latitude 63.469
Longitude -171.742
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is on the north bank of the Moghoweyik River, 3/4 mile upstream from the mouth on the west coast of St. Lawrence Island. It is located within 1/4 mile and is locality 4 of Cobb (1972). Cobb (1980) summarized relevant references under the name 'Moghoweyik R., lower'.

Geologic setting

Geologic description

Molybdenite mineralization here is in the Sevuokuk pluton, a mid-Cretaceous (108 +/- 3.2 Ma) composite body that includes biotite hornblende quartz monzonite and biotite quartz monzonite phases (Csejtey, Patton, and Miller, 1971; Patton and Csejtey, 1980). At this site, molybdenite occurs in thin veinlets cutting highly oxidized pyritiferous biotite quartz monzonite. The quartz monzonite is also cut by quartz veins and aplite dikes (Patton and Csejtey, 1971, p. C10). Three grab samples contained 7, 500, and 1,500 ppm molybdenum and 700, 150, and 15 ppm copper respectively (Patton and Csejtey, 1971. p. C8). A pan concentrate from the riverbed gravels at this locality contained 70 ppm molybdenum and 5,000 ppm tungsten (Patton and Csejtey, 1971, p. C10).
Geologic map unit (-171.744787862025, 63.4680667381745)
Mineral deposit model Porphyry Mo, low-F? (Cox and Singer, 1986; model 21b?).
Mineral deposit model number 21b?
Age of mineralization Mid-Cretaceous, the age of the host Sevuokuk pluton (108 +/- 3.2 Ma; Patton and Csejtey, 1980).
Alteration of deposit Pyrite is apparently abundant and disseminated in the biotite quartz monzonite as well as accompanying molybdenite in veins. Pyrite oxidation is well-developed and other alteration is probably present although not described.

Production and reserves

Workings or exploration Three grab samples contained 7, 500, and 1,500 ppm molybdenum and 700, 150, and 15 ppm copper respectively (Patton and Csejtey, 1971. p. C8). A pan concentrate from the riverbed gravels at this locality contained 70 ppm molybdenum and 5,000 ppm tungsten (Patton and Csejtey, 1971, p. C10).
Indication of production None

References