Unnamed (ridge northeast of Brooker Mountain) (ARDF #MM025) Ag, Sb

Unnamed (ridge northeast of Brooker Mountain)

Prospect, Inactive

Commodities and mineralogy

Main commodities	Ag; Sb
Other commodities	As; Au; Cu; Pb; Zn
Ore minerals	arsenopyrite; galena; pyrite; scorodite; sphalerite; stibnite
Gangue minerals	quartz

Geographic location

Quadrangle map, 1:250,000-scale	MM
Quadrangle map, 1:63,360-scale	C-3
Latitude	63.5115
Longitude	-151.0403
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This prospect is at an elevation of about 3100 feet on the southeast- trending ridge about midway between Brooker Mountain and Alpha Ridge. It is in the SE1/4 section 21, T. 16 S., R. 18 W., Fairbanks Meridian. The location is accurate within 500 feet. The prospect corresponds to number 4 of Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description The country rock at this prospect is feldspar-quartz-mica schist of the Birch Creek Schist (Bundtzen, 1981). Although the mineral deposit is not exposed, the distribution of float in relation to old pits and topography indicates that the deposit is a vein which strikes about EW and dips at a moderate or shallow angle to the south (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 4). A selected sample of sulfide-rich material in a pit assayed 144 ounces of silver per ton, 18 percent arsenic, and 45 percent antimony. It also contained 0.365 percent copper, 8.4 percent lead, and 3.75 percent zinc (Thornsberry, McKee, and Salisbury, 1984, v. 2). Some of the material contains about 50 percent stibnite. The high arsenic value indicates that arsenopyrite or its oxidation product scorodite is present.
Geologic map unit	(-151.042585234926, 63.5109909331408)
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 vein has been explored by several shallow pits of unknown date.
Indication of production	Undetermined
Additional comments The prospect is in Denali National Park and Preserve.

References

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. Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p. 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.
Reporters	C.C. Hawley
Last report date	4/18/2000