Upper Bosart

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag
Other commodities Cu; Pb; Sb; Zn
Ore minerals galena; sphalerite; stibnite; tetrahedrite
Gangue minerals quartz; siderite

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5697
Longitude -150.9071
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Upper Bosart prospect is at an elevation of about 3100 feet on north spur of Wickersham Dome. It is in the NE1/4 SE1/4 of section 31, T. 15 S., R. 17 W. Fairbanks Meridian. The location is accurate within 300 feet. The site corresponds to number 35 of Bundtzen, Smith, Tosdal (1976), 41 of Bundtzen (1981), 47 of Thornsberry, McKee, and Salisbury (1984), and 112 of Hawley and Associates (1978).

Geologic setting

Geologic description

The country rocks at the Upper Bosart prospect are quartz-feldspar schist and micaceous quartz schist of the upper Precambrian Birch Creek Schist (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 47). The deposit consists of a mineralized quartz-siderite(?) vein that is poorly exposed in shallow trenches. The vein strikes about N 40 E, dips steeply, and ranges from about 1 to 4 feet thick. Selected sulfide-rich samples assayed up to 0.88 percent copper, 32.8 percent lead, 20.4 percent zinc, 1.36 percent antimony, and 26.4 ounces of silver per ton. A representative sample assayed about 1.5 ounces of silver per ton, 2.75 percent lead, and 1.15 percent zinc (Thornsberry, McKee, and Salisbury, 1984; Hawley and Associates, 1978). The assay values suggest that the sulfide minerals include galena, sphalerite, tetrahedrite, and possibly stibnite. The deposit is similar to those at the Florence (MM082) and Bosart (MM074) prospects.
Geologic map unit (-150.909388732478, 63.5691947359358)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization The deposit is assumed to be Eocene (see record MM091).

Production and reserves

Workings or exploration The prospect was explored by shallow trenches, only some of which reached bedrock. The date of this work is not known, but the nearby Bosart vein (MM074) was first prospected before 1931 (Wells, 1933).
Indication of production None

Additional comments

The prospect is in Denali National Park and Preserve.

References