Emma Creek Mine, Koyukuk Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Emma Creek Mine	Mine
Koyukuk Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Location: Emma Creek is an east-flowing tributary to the Middle Fork, Koyukuk River; its mouth is about 4.5 miles north of Coldfoot. The coordinates are about 0.8 mile upstream from the mouth; placer mining has occurred for about 0.5 mile downstream and 2 miles upstream. The location is accurate.
Geology: Gold was discovered on Emma Creek in 1900. The gold occurs in the modern channel and on a high bench. The productive portion of the modern channel is centered in a steep canyon cut through crystalline limestone. The canyon begins about a mile above the mouth of Emma Creek and extends upstream 1/2 mile or more. Most of the placer gold in this part of Emma Creek was concentrated at the upper end of the canyon, both within the canyon and in a gravel fan at its lower end. The richest ground was at the lower end of the canyon (Maddren, 1913). Gold also occurs in a high bench channel on the south side of Emma Creek about a half mile from the mouth. This channel lies about 30 feet above the modern creek bed and is approximately 150 feet wide. Toward the Middle Fork, it diverges from the modern creek bed and swings to the southeast. The bench gravel is small and waterworn and contains numerous granite and limestone boulders (Reed, 1938). The depth to bedrock varies from 5 to 91 feet. From the top, the section consists of a foot of moss, 0-50 feet of sand and clay, and 4-40 feet of gravel. All of the gravel, except the lower 4-5 feet is frozen. The gold is coarse and angular and commonly attached to quartz (Bliss and others, 1988). The gold on bedrock was in small nuggets valued at $0.25 to $1 (gold at $20 per ounce.) The bedrock in the area around the high channel is micaceous and graphitic schist with bands of limestone (Reed, 1938). Bliss and others (1988) suggested that the source of the gold may be the numerous quartz veins that occur in the drainage area. Three samples of gold from Emma Creek have a median fineness of 905 and median trace elements contents of 0.047% copper, 50 ppm lead, 80 ppm antimony, and 0.31% mercury (Mosier and Lewis, 1986). Early mining of the modern channel was by sluicing, and of the high bench by drifting and open cuts. Mining in the modern channel was complicated by numerous large boulders, 3 to 10 feet in diameter, above and below the canyon. Small-scale mining was reported in 1974 (Mulligan, 1974). According to Kurtak and others (2002) a suction dredge has been used on Emma creek to clean out potholes in the bedrock. Mining on Emma Creek has been regularly reported during the 1980's, 1990's (Eakins and others, 1983 and 1985; Bundtzen and others, 1984, 1986, 1990, and 1992; Green and others, 1989; Swainbank and others, 1993), and as recently as 2000 (Szumigala and others, 2001). Most of the production from this creek occurred prior to 1930. The value of the gold produced from 1900 to 1909 was estimated to be $160,000 (gold at $20/ounce), most of which was produced from 1900 to 1902 (Maddren, 1913). According to Reed (1938) as much as $12,000 (gold at $35/ounce) was produced from the high channel through 1928.
Workings: Early mining of the modern channel was by sluicing, and of the high bench by drifting and open cuts. Mining in the modern channel was complicated by numerous large boulders, 3 to 10 feet in diameter, above and below the canyon. Small-scale mining was reported in 1974 (Mulligan, 1974). According to Kurtak and others (2002) a suction dredge has been used on Emma creek to clean out potholes in the bedrock. Mining on Emma Creek has been regularly reported during the 1980's, 1990's (Eakins and others, 1983 and 1985; Bundtzen and others, 1984, 1986, 1990, and 1992; Green and others, 1989; Swainbank and others, 1993), and as recently as 2000 (Szumigala and others, 2001).
Age: Quaternary.
Production: Most of the production from this creek occurred prior to 1930. The value of the gold produced from 1900 to 1909 was estimated to be $160,000 (gold at $20/ounce), most of which was produced from 1900 to 1902 (Maddren, 1913). According to Reed (1938) as much as $12,000 (gold at $35/ounce) was produced from the high channel through 1928.

Commodities (Major) - Au
Development Status: Yes; small
Deposit Model: Placer Au (Cox and Singer, 1986; model 39a)

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Link to USGS - Alaska:	WI118

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References