Upper Ridge

Mine, Inactive

Commodities and mineralogy

Main commodities Sb
Other commodities Ag; Au; Zn
Ore minerals kermesite; limonite; pyrite; stibiconite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-1
Latitude 63.7452
Longitude -150.3891
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Upper Ridge mine (Cobb, 1980 [OFR 80-363]) is at an elevation of about 2800 feet on the divide between Little Moose and Stampede creeks. It is about 2300 feet east of the center of section 36, T. 13 S., R. 15 W., Fairbanks Meridian. The location is accurate within 500 feet. The mine site corresponds to number 67 of Bundtzen, Smith, and Tosdal (1976), 76b of Bundtzen (1981), and 109 of Thornsberry, McKee, and Salisbury (1984). Hawley and Associates (1978) position it nearly at the common end line between the Ridge No. 1 and 2 claims.

Geologic setting

Geologic description

The country rocks at the Upper Ridge mine are quartz-feldspar schist and gneiss, and quartzite of the Birch Creek Schist (Bundtzen, 1981). The deposit is on the north flank of the Stampede warp (antiform) (Thornsberry, McKee, and Salisbury, 1984, plate K-4; Hawley and Associates, 1978, fig. 4.1-A(2)).
The principal deposit was a lens of massive stibnite that has been largely mined out. Small veins of stibnite, partly oxidized to stibiconite and kermesite, remain at the mine site. There also are quartz veins, stained with limonite after pyrite. A grab sample of stibnite-bearing float assayed 38.5 percent antimony and 0.026 ounce of gold per ton. A sample of a quartz-stibnite gash vein assayed 14.5 percent antimony and 0.06 ounce of gold per ton (Hawley and Associates, 1978). Sulfidized schist near the occurrence contained 1.2 percent zinc and anomalous amounts of copper, lead, and silver (Bundtzen, 1981, p. 226).
Geologic map unit (-150.391398952667, 63.7447094072466)
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 (see record MM091).
Alteration of deposit Partial oxidation of stibnite. Iron-oxide alteration.

Production and reserves

Workings or exploration The stibnite ore body was surface mined.
Indication of production Yes; small
Production notes An unknown amount of antimony ore was mined at the Upper Ridge deposit.

Additional comments

The Upper Ridge mine is in Denali National Park.

References