Spruce Creek No. 1

Prospect, Inactive

Alternative names

Ridgetop

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Mo; Pb; Th; U; Zn
Ore minerals galena; limonite; malachite; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5818
Longitude -150.7112
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Spruce Creek No. 1, or Ridgetop, prospect (Cobb, 1980 [OFR 80-263]) is at an elevation of about 4250 feet about 1600 feet west of Spruce Peak, on the divide between Crevice and Spruce creeks. The location is probably accurate within 250 feet. The prospect corresponds roughly to soil sample locality 242 of Hawley and Associates (1978), and to locality 62 of Bundtzen (1981). It probably is the same as occurrence 84 of Thornsberry, McKee, and Salisbury (1984), although they locate the prospect north of the divide.

Geologic setting

Geologic description

This deposit is a sulfide-bearing quartz vein in a shear zone in metafelsite of the lower Paleozoic Spruce Creek sequence. A fault that strikes NW cuts the metafelsite near the prospect, but whether the fault and the vein are related is uncertain (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984, fig. K-2).
The prospect was first described by Davis (1923, p. 133), who called it the Ridgetop. He described the deposit as a 12-foot-wide lode that was iron- and copper-stained and contained 'a very little galena.' Wells (1933, p. 374-375) apparently called the prospect Spruce Creek No. 1, and described it as a 12-foot-thick pyritic quartz vein. When Well visited in 193l, the prospect pits were sloughed. No assays were given by either Davis or Wells. The prospect was examined by Hawley and Associates in 1976 (1978, samples 242 and 243), who collected two soil samples. Soil at the prospect (no. 242) contained 0.51 ppm gold and 3.2 ppm silver. Reddish residual soil about 400 feet from the prospect (no. 243) contained 1.2 ppm gold, 90 ppm silver, 485 ppm copper, 10500 ppm lead, and 7000 ppm zinc. Bundtzen (1981, locality 62) collected 5 mineralized rock samples that assayed 0.01 to 0.225 ounce of gold per ton, and up to 86 ppm molybdenum, 9.7 ppm uranium, and 14.7 ppm thorium.
Geologic map unit (-150.713484272468, 63.5812992624668)
Mineral deposit model Low-sulfide gold-quartz vein (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. Oxidation of iron and copper minerals.

Production and reserves

Workings or exploration The prospect was explored by shallow pits dug before 1922 (Davis, 1923). There has been little additional work since then , but natural rubble crops of quartz vein material are widespread on the divide between Spruce and Crevice Creeks.
Indication of production None

Additional comments

The prospect is in Denali National Park and Preserve.

References