Unnamed (on Lost River)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Sn
Other commodities Ag; Pb
Ore minerals cassiterite; galena

Geographic location

Quadrangle map, 1:250,000-scale TE
Quadrangle map, 1:63,360-scale B-5
Latitude 65.449
Longitude -167.182
Nearby scientific data Find additional scientific data near this location
Location and accuracy Lost River is the main south-flowing drainage in the York Mountains of western Seward Peninsula. Its mouth on the Bering Sea is 21 miles west of Brevig Mission. This locality is four miles upstream from the mouth and just below the confluence with Tin Creek , a significant east tributary to Lost River. The occurrence is in alluvial gravels of the active Lost River drainage just west of the outcropping Idaho lode prospect (TE040). It is locality 42 of Cobb and Sainsbury (1972). It was not included separately by Cobb (1975).

Geologic setting

Geologic description

Bedrock in this drainage and its tributaries are various Ordovician limestone facies locally intruded by felsic and mafic dikes and granite stocks (Sainsbury, 1969). The USBM completed two churn-drill holes in the active drainage of Lost River here (Mulligan, 1959, p. 12-15). This locality is just west of the outcropping Idaho lode prospect and downstream of the fluorite-beryllium-sulfide mineralization along the Rapid River fault at the Bessie-Maple (TE038) and Lost River valley lode (TE041) prospects. The two churn-drill holes showed the 5 to 6 feet of gravel on bedrock here to contain 0.29 and 0.35 pounds of tin per cubic yard. The gravels at this locality are 9 and 10 feet thick. Bedrock described from the bottom of one of these holes is dolomite with chlorite, fluorite, and a trace of pyrite. The gravel in the holes also contained a trace of silver and one contained 0.04 pounds of lead per cubic yard. Galena was identified in the lead-bearing material but otherwise the mineralogy of the heavy mineral concentrates was not reported. Traces of lead and zinc were found in the bedrock but the the related minerals could not be identified (Mulligan, 1959, p. 15).
Geologic map unit (-167.184712975076, 65.4482212344118)
Mineral deposit model Alluvial tin placer (Cox and Singer, 1986; model 39e)
Mineral deposit model number 39e
Age of mineralization Quaternary.

Production and reserves

Workings or exploration Two USBM churn-drill holes have been completed here (Mulligan, 1959).
Indication of production None
Reserve estimates Not defined; low grades are indicated
Production notes None