Unnamed (ridge crest southeast of Spruce Peak)

Occurrences, Inactive

Commodities and mineralogy

Main commodities Ag; Pb
Other commodities As; Au; Sb
Ore minerals arsenopyrite; galena; goethite; jarosite; limonite; pyrite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5742
Longitude -150.6819
Nearby scientific data Find additional scientific data near this location
Location and accuracy This record describes a mineralized area on the ridge southeast of Spruce Creek. The location marks the approximate center of the area, in the SW1/4 NE1/4 section 32, T. 15 S., R. 16 W., Fairbanks Meridian. The location is accurate. It corresponds to occurrence 90 (3 symbols) of Thornsberry, McKee, and Salisbury (1984, fig. K-8).

Geologic setting

Geologic description

The country rocks in the general area of these occurrences include metafelsite of the Spruce Creek sequence, and mica schist and quartzite of the Birch Creek Schist (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, fig. K-2). The occurrences consist of iron-stained quartz veins, quartz float, and soil, in fault-controlled saddles along the ridge southeast of Spruce Creek. The veins strike NE, about parallel to the strike of the hostrocks and the faults. The veins and fault zones are poorly exposed, but probably range in width from about a foot to tens of feet. All are marked by quartz fragments and by red or orange limonitic soils that contain goethite and jarosite.
In 1983, the U.S. Bureau of Mines sampled four mineralized fault zones along the ridge (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 90). Three of these zones contained 0.0 to 0.12 ppm gold, 2.4 to 9.7 ppm silver, 110 to 710 ppm lead, and 155 to 465 ppm arsenic, and one contained 1 ppm silver, 305 ppm antimony, and 100 ppm zinc. Oxidation of the deposits is pervasive. Judged from their assays and character of the limonite, the quartz veins probably contained pyrite and small amounts of arsenopyrite, galena, and stibnite.
Geologic map unit (-150.684182705665, 63.5737000668038)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization The deposit is assumed to be Eocene (see record MM091).
Alteration of deposit Silicification. Pervasive oxidation of deposits.

Production and reserves

Workings or exploration Surface mapping and sampling. The deposits were discovered in 1983 and probably have not been further prospected.
Indication of production None

Additional comments

The area is in Denali National Park and Preserve.

References