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

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

Location: Mascot Creek flows south about 7 miles to the Glacier River. The coordinates are at about the midpoint of a 3-mile-long stretch of placer mining on Mascot Creek; it is in the SW1/4 of section 18, T. 31 N., R. 13 W., of the Fairbanks Meridian. The location is accurate.
Geology: Most of the mining on Mascot Creek has been along a 3-mile stretch of the creek, downstream from the forks located approximately 7 miles above the mouth. Mining and prospecting above and below this section of the creek has generally proved to be unproductive. The gold occurs both in the modern stream channel and in high channels. Most of the gold has been taken from the modern stream channel. The gravel is waterworn and fine with few boulders; none of the gravel is frozen. The gravel in the modern channel generally is 0.5 to 3 feet thick. The relative ease with which these thin gravels could be mined made Mascot Creek one of the more profitable placer creeks in the district. The gold in the modern channel is just above and below the bedrock surface; it typically is coarse and well worn. Nuggets with values up to $100 (5 oz) have been recovered (Maddren, 1913). In one location near the upper end of the mined area, the gold was 90% coarse and 10% fine. Fineness ranged from about 942 to 977. Reed (1938) estimated that the value of the ground being mined in the modern channel in 1938 was $1.25 to nearly $7 per square foot of bedrock. Gold also occurs in remnants of a high channel on Mascot Creek. These remnants typically are along the right limit (west side) of the creek and a few tens of feet above the modern channel. Reed (1938) described one of these remnants as about 100 feet long and 10 feet wide; another was about 30 feet above the modern stream. According to Reed (1938), the bedrock in Mascot Creek is graphitic to quartz schist. The quartz schist is reddish from iron staining; its relation to the placer gold is unknown. According to Schrader (1904), mica schist on bedrock contains quartz stringers and a few porphyry dikes. Bliss and others (1988) speculated that the gold might be derived from these quartz stringers. Kurtak and others (1999) described the bedrock of Mascot Creek as quartz-mica schist, graphitic schist, phyllite, siliceous mudstone and schistose quartzite.
Workings: The Mascot Creek placer was extensively mined and prospected, mostly along a 3-4 mile section of the modern channel beginning about 3 miles above the mouth. Most mining was by ground sluicing and shoveling in. Although bedrock beneath the placer gravels in this part of the creek was thought to be about 20 feet deep, thawed gravel apparently prevented the prospect shafts from reaching bedrock. The last extensive mining reported on the creek was in the 1980's (Kurtak and others, 1999). The creek is considered to be essentially mined out except for perhaps a few small pockets. Some very small scale mining (hand methods?) directed at these pockets appears to have continued into the mid-1990's (Kurtak and others, 1999).
Age: Quaternary.
Production: Maddren reported total gold production through 1910 as about $150,000 (approx. 7,900 oz.). Mining has continued intermittently since that time, but there is no record of this later production.

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:	WI025

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References