Kiruktagiak River

Occurrence, Inactive

Commodities and mineralogy

Main commodities P
Other commodities U; V
Ore minerals fluorapatite; vanadinite
Gangue minerals calcite; dolomite; fluorite; quartz

Geographic location

Quadrangle map, 1:250,000-scale CL
Latitude 68.38
Longitude -152.9
Nearby scientific data Find additional scientific data near this location
Location and accuracy Located on west side of upper Kiruktagiak River, 450-1200 m above mouth of Monitis Creek. Known to within one mile.

Geologic setting

Geologic description

Phosphate deposits are restricted to 40 ft. black shale and chert horizon of the Alapha Limestone of late Mississippian age. Rocks of phosphatic zone are chiefly a mixture of phosphatic material, CaCO3, silt, and clay; in some places secondary purple fluorite is on bedding surfaces and in veinlets. Phosphatic material occurs as pellets (oolites) as much as 10 mm long and are composed of carbonate-fluorapatite. There are marked lateral variations in lithologic character and phosphate content. On the Kiraktagiak River and Monotis Creek, measured sections indicate that the phosphatic units are either lenticular or displaced by small folds and faults.
Geologic map unit (-152.902857116782, 68.3795637013088)
Mineral deposit model Bedded phosphorite (Cox and Singer, 1986; model 34c).
Mineral deposit model number 34c
Age of mineralization Mississippian.

Production and reserves

Workings or exploration A 38 ft. thick zone of chert and shale unit in the Mississippian Alapha limestone contains an average of 12 percent P2O5; The upper 19 ft. averages 19 percent P2O5. A 27 inch thick sequence contains 27 percent P2O5. Samples analyzed for vanadium contained 0.07 percent - 0.49 percent V2O5. Highest uranium content was 0.21 percent U. Samples collected by the USBM contained up to 20.6 percent phosphate.
Indication of production None