Unnamed (near elevation 3228 south of the Stampede Mine)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Sb
Other commodities Ag; Au; Cu; Mo; Pb; Zn
Ore minerals limonite; pyrite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-1
Latitude 63.7297
Longitude -150.4018
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on an east-trending ridge about a mile south-southwest of the Stampede mine (MM144). It is about 0.2 mile east-southeast of hilltop elevation 3228, near the center of section 2, T. 14 S., R. 15 W., Fairbanks Meridian. The occurrence corresponds to number 65b (map number 65) of Bundtzen, Smith, and Tosdal (1976), 124 of Hawley and Associates (1978), and 107 of Thornsberry, McKee, and Salisbury (1984). The location is accurate within 500 feet.

Geologic setting

Geologic description

This occurrence consists of stibnite-bearing quartz veins in the southwest extension of the Stampede fault (Hawley and Associates, 1978, fig. 4.1-A(2); White, 1942, pl. 49). At the occurrence, the fault strikes about N 35 E and dips 45 SE, essentially parallel to and nearly coincident with, the contact between quartzitic schist (northwest) of the Birch Creek Schist and graphitic rocks of the Keevy Peak Formation (Hawley and Associates, 1978, fig. 4.1-A(2); Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, pl. K-4).
Where the fault crosses the ridge below hilltop 3228, it is a limonitic silicified zone that contains pyrite and small amounts of stibnite (oral communication, Earl Pilgrim, 1976). A sample collected by Bundtzen, Smith, and Tosdal (1976) assayed about 0.05 percent antimony, 51 ppm molybdenum, and traces of gold, copper, silver, and zinc. Hawley and Associates (1978, Fig. 4.1-A(2)) ran a soil line down the ridge from hilltop 3228 across the Stampede fault. At about the trace of the fault, the soil samples contained up to 160 ppm antimony, 3.8 ppm silver, 42 ppm molybdenum, and weakly anomalous amounts of copper, lead, and zinc.
Geologic map unit (-150.404097085544, 63.7292090110445)
Mineral deposit model Simple Sb deposit (Cox and Singer, 1986; model 27d).
Mineral deposit model number 27d
Age of mineralization The deposit is assumed to be Eocene, the probable age of the Stampede antimony deposit (MM144), (also see record MM091).
Alteration of deposit Silicification. Iron-oxide alteration.

Production and reserves

Workings or exploration The occurrence was discovered by Earl Pilgrim, the longtime operator of the Stampede mine, who found stibnite in a fault zone where it crosses the ridge below elevation 3228. Hawley and Associates (1978, fig. 4.1-A(2) made a reconnaissance map of the area and collected soil samples across the Stampede fault and a possible subsidiary fault to the south. The soils near the occurrence are mainly anomalous in antimony (to 160 ppm), silver (to 3.8 ppm), and molybdenum (to 42 ppm), and weakly anomalous in copper, lead, and zinc. The molybdenum appears to correlate with the graphitic rocks. Bundtzen (1981) collected gossan at the occurrence that contained about 500 ppm antimony and 51 ppm molybdenum.
Indication of production None

Additional comments

The site is in Denali National Park and Preserve.

References