Long Creek

Mine, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag; Sn
Ore minerals cassiterite; gold

Geographic location

Quadrangle map, 1:250,000-scale RB
Quadrangle map, 1:63,360-scale B-6
Latitude 64.38473
Longitude -155.52771
Nearby scientific data Find additional scientific data near this location
Location and accuracy Long Creek is a south-flowing tributary of the Sulatna River. Mining took place for 61/2 miles along the creek, centered 5 miles northwest of Monument Rocks. Coordinates corresponding to location 13 of Cobb (1972 [MF-405]) mark the approximate center of placer tailings marked on the Ruby B-5 quadrangle (USGS topographic map, 1952, minor revisions in 1973) at the mouth of Snow Gulch. This site is located in section 4, T. 13 S., R. 17 E. of the Kateel River meridian. The location is accurate.

Geologic setting

Geologic description

The bedrock underneath Long Creek is mostly cherty siliceous rock with talcose layers and some greenstone (Mertie, 1936). Granite is found in the divide between Long and Flint Creeks (Mertie, 1937). The pay streak is located east of the present course of Long Creek and is at least 6 1/2 miles long, although sporadic (Brooks, 1916). In some places it is as much as 100 feet wide (Eberlein and others, 1977). The ground runs from 0.04 to 0.72 ounces per square foot of bedrock, and under 20 to 80 feet of overburden (Eakin, 1914 [B578]; Mertie and Harrington, 1916).
The gold is found on and in crevices in the bedrock and on a false clay bedrock just above barren gravel (Mertie and Harrington, 1916). The gold is generally spongy and not well rounded (Mertie, 1936). It is both fine and coarse grained; the largest nugget weighed 131 ounces. Several other nuggets weighed about 35 ounces. Assays show the gold to be about 857 parts gold per thousand and 135 parts silver per thousand. The gold is accompanied by cassiterite (Eberlein and others, 1977).
Gold was first discovered on Long Creek in 1910, and since then Long Creek experienced almost continuous mining through 1977 (Eberlein and others, 1977). Long Creek experienced intermittent mining from the 1970s until 1988 and continuous mining and exploration from 1988 through 1993 (Green and others, 1989; Bundtzen and others, 1990; Swainbank and others, 1991; Bundtzen and others, 1992; Swainbank and others, 1993; Bundtzen and others, 1994). The early work was done by drift mining, but later work included open-cut mining and reworking old tailings. All post-1940 mining was done with open-cut methods (Eberlein and others, 1977).
Production from 1910 through 1933 was at least 38,500 ounces of gold, and total production through 1977 may have been twice that much (Mertie, 1936; Cobb and Chapman, 1981).
Geologic map unit (-155.530129285867, 64.3841246079306)
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 Long Creek has experienced nearly continuous mining from 1910 to 1993 (Green and others, 1989; Bundtzen and others, 1990; Swainbank and others, 1991; Bundtzen and others, 1992; Swainbank and others, 1993; Bundtzen and others, 1994). Early mining was done by drift mining, and later mining was by open-cut methods and re-working old tailings.
Indication of production Yes; small
Reserve estimates According to Eberlein and others (1977), the major part of the mining area is probably nearly worked out, however some peripheral gold-bearing placers may remain.
Production notes Production between 1910 and 1933 was at least 38,500 ounces of gold. Total production on Long Creek through 1977 may have been at least twice as much (Cobb and Chapman, 1981).

Additional comments

Tributaries of Long Creek that have experienced mining or prospecting are Greenstone Creek (RB021), Midnight Creek (RB019), Flat Creek (RB016), Short Creek (RB018), Fifth of July Creek (RB017), Fourth of July (RB022), and Basin Creek (RB013). Tributaries of Basin Creek, Willow Creek (RB015) and Swift Creek (RB014) have also experienced mining and or prospecting.

References

MRDS Number A010743; A015535

References

Reporters C.E. Cameron (Alaska Division of Geological and Geophysical Surveys)
Last report date 3/22/2000