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Upper Bosart

Prospect, Inactive

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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 DN
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 (DN082) and Bosart (DN074) prospects.
Geologic map unit (, )
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 DN091).

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 (DN074) was first prospected before 1931 (Wells, 1933).
Indication of production None

Additional comments

The prospect is in Denali National Park and Preserve.

References

MRDS Number A011289

References

Bundtzen, T.K., 1981, Geology and mineral deposits of the Kantishna Hills, Mt. McKinley quadrangle, Alaska: M. S. Thesis, University of Alaska, College, Alaska, 238 p.
Bundtzen, T.K., Smith, T.E., and Tosdal, R.M., 1976, Progress report--Geology and mineral deposits of the Kantishna Hills: Alaska Division of Geological and Geophysical Surveys Open-File Report AOF-98, 80 p., 2 sheets, scale 1:63,360.
Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p.
Hawley, C. C. and Associates, Inc, 1978, Mineral appraisal of lands adjacent to Mt. McKinley National Park, Alaska: U. S. Bureau of Mines Open-File Report 24-78, 275 p. (paged by sections).
Thornsberry, V. V., McKee, C. J., and Salisbury, W. G., eds, 1984, 1983 Mineral Resource Studies: Kantishna Hills and Dunkle Mine Areas, Denali National Park and Preserve, Alaska: U. S. Bureau of Mines Open-File Report 129-84. 3 Volumes: v. 1, Text; v. 2, Appendices; v. 3, Maps. Prepared by Salisbury & Dietz, Inc., Spokane, WA.
Wells, F. G., 1933, Lode deposits of Eureka and vicinity, Kantishna district, Alaska: U. S. Geological Survey Bulletin 849-F, p. 335-379.
Reporters C.C. Hawley
Last report date 4/29/2001