Spruce Creek (lode)

Occurrence, Undetermined

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Pb; Zn
Ore minerals gold; galena; sphalerite
Gangue minerals calcite; quartz

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). The location is probably accurate to within 1,000 feet.

Geologic setting

Geologic description

Spruce Creek has been known as a placer deposit (see RM033) since before 1915, when the earliest known report of mining evidence was made by Maddren (1915). The Spruce Creek occurrence may be the potential source for Spruce Creek placer gold. 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). Massive, unlayered porphyritic mafic flows varying in color from dark green to reddish to a distinct dark purple and interbedded layered, intermediate to felsic pyroclastics and poly-lithic volcaniclastics were encountered in two drill holes drilled by Nyac Gold LLC in 2013 (Flanders, 2013). The alteration observed in these two drill holes was silicification and silica-carbonate flooding adjacent to quartz veining and stockwork tectonized zones. Mineralization was found in yellowish-white calcite and quartz veining and translucent chalcedonic quartz veining in a foliated tectonized zone (Flanders, 2013).
In 2005-2006, a soils sampling program was conducted. In 2010, Nyac Gold LLC collected stream sediment samples at Spruce Creek (Flanders, 2013).
Geologic map unit (, )
Mineral deposit model Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Mineralization likely associated with Cretaceous plutons (Flanders, 2013).
Alteration of deposit Alteration observed is silicification and silica-carbonate flooding adjacent to quartz veining and stockwork tectonized zones (Flanders, 2013).

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.
In 2005-2006, a soil sampling program was conducted covering approximately half of a subtle aeromagnetic anomaly. In 2010, stream sediment samples were collected at Spruce Creek by Nyac Gold LLC (Flanders, 2013).
In 2013 Nyac Gold LLC drilled two holes targeting a fault zone exposed during placer mining and thought to be mineralized. Drill hole NYC13-03 intersected a 10-foot zone from 457 to 467 feet containing 32 ppb Au, 2.7 ppm Ag, 134 ppm Pb, 256 ppm Zn, and 4 ppm Mo. Another 10-foot mineralized interval in the same drill hole from 507 to 517 feet contained 0.220 gpt Au, 2.2 ppm Ag, 98 ppm Pb, 288 ppm Zn, and 6.1 ppm Cd (Flanders, 2013).
Indication of production None

References