Spruce Creek

Mine, Undetermined

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale RM
Quadrangle map, 1:63,360-scale A-3
Latitude 61.0671
Longitude -159.7804
Nearby scientific data Find additional scientific data near this location
Location and accuracy The location of Spruce Creek is probably incorrect on the USGS 1:63,360 topographic map. It is probably the first creek southwest of Bonanza Creek (RM031); both are east-flowing tributaries of upper Bear Creek. In 2006, the local miners place Spruce Creek in sections 5 and 8, T. 11 N., R. 59 W., of the Seward Meridian (D.J. Grybeck, field work and discussions with miners in the area, 2006).

Geologic setting

Geologic description

Early reports indicated that the lower part of Spruce Creek was placer mined where it crosses bench deposits along Bear Creek. As described by Maddren (1915), gravel deposits at the mouth of the creek are as much as 400 feet thick. Gravels along the active drainage are 20 to 30 feet thick 1,500 feet upstream of the mouth, and the headwaters of the creek cut into bedrock. Where the alluvial deposits are 20 to 30 feet thick, they consist of 2 to 4 feet of muck, 2 to 3 feet of coarse gravel with boulders as much as 1 foot in diameter, 1 to 1.5 feet of blue clay, and brown sandy and pebbly clay to bedrock. Most of the gold occurred in the blue and brown pebbly clays and on bedrock. Some of the gold was coarse and attached to quartz. Maddren (1915) thought that the gold could have been derived from the contact zone around an intrusion at the head of the creek. Bedrock in the Spruce Creek drainage includes thermally metamorphosed Jurassic volcanic rocks developed around a mid-Cretaceous granitic stock (Box and others, 1993; Wenz, 2005).
The location of the Spruce Creek that Maddren (1915) described is somewhat uncertain. The Spruce Creek labeled on the current USGS 1:63,360-scale topographic map is not in the same location as the Spruce Creek known to the miners working in the area in 2006. The Spruce Creek on the topographic map is generally parallel to and about two miles to the southwest of Bonanza Creek. The local miners consider Spruce Creek to be the creek generally parallel to and about 1 mile southwest of Bonanza Creek in sections 5 and 8.
In the late 1990s Nyac Mining Company mined extensively on the Spruce Creek about a mile southwest of Bonanza Creek and produced a minimum of 25,000 ounces of gold (Wenz, 2005). The area has now been reclaimed. It is uncertain whether the mining prior to 1915 was on the Spruce Creek as labeled on the current topographic maps or on the parallel nearby creek about a mile southwest of Bonanza Creek that was mined by Nyac Mining Company in the 1990s.
Geologic map unit (-159.78270257936, 61.0663694894051)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary.

Production and reserves

Workings or exploration Open-cut placer mining took place along lower Spruce Creek until about 1920. Some of this work included a 280-foot long, 15- to 20-foot wide, and 10-foot-deep trench built as a bedrock drain. In the 1990s, Nyac Mining Company mined extensively on Spruce Creek from surface cuts. (But see the location and geologic description for the uncertainty of the location of Spruce Creek.)
Indication of production Yes; small
Production notes In the 1990s, Nyac Mining Company produced a minimum of 25,000 ounces of gold from Spruce Creek. (But see the location and geologic description for the uncertainty of the location of Spruce Creek.)

References