Brooker Mountain

Prospect, Inactive

Commodities and mineralogy

Main commodities Sb
Other commodities Ag; Au; Bi; Pb; Zn
Ore minerals cerussite; galena; limonite; stibiconite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-3
Latitude 63.5021
Longitude -151.0514
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of about 3450 feet on the northeast flank of Brooker Mountain above Reinhart Creek . It is about 800 feet north-northwest of the center of section 23, T. 16 S., R. 18 W., Fairbanks Meridian. The location is accurate within about 500 feet. The prospect is number 2 of Bundtzen, Smith and Tosdal (1976), Bundtzen (1981), and Thornsberry, McKee and Salisbury (1984), and number 21 of Hawley and Associates (1978).

Geologic setting

Geologic description

The country rock at this prospect is chlorite-quartz-muscovite schist of the Birch Creek Schist (Bundtzen, 1981, p. 206). A polymetallic quartz vein is poorly exposed but appears to be nearly vertical and to strike about N 60 E. The vein is pyritic and locally oxidized to limonite. The quartz locally contains as much as several percent of stibnite. A limonitic quartz vein assayed 1.18 percent lead, 12.1 ounces of silver per ton, 0.63 percent antimony and 0.26 percent bismuth (Bundtzen, 1981, p. 198, 211) . T. K. Hinderman collected a gossan sample that contained 3 percent lead, 4900 ppm silver, 1.6 ppm gold, and 1.55 percent antimony (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 2). The presence of galena or possibly its oxidation product cerussite is inferred from the lead content of samples of vein material and gossan.
Geologic map unit (-151.053684360536, 63.5015905150186)
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).
Alteration of deposit Iron-oxide alteration. Possible oxidation of lead mineral.

Production and reserves

Workings or exploration The prospect was explored by a shallow, 65-foot-long bulldozer trench and a small pit. Workings are sloughed and timber at the site for a cabin had rotted by 1983.
Indication of production None

Additional comments

The prospect is in Denali National Park and Preserve.

References