Tracy Arm; Jingle-Jangle; Neglected Prize Prospect, Petersburg Mining District, Juneau, Alaska, USAi

Regional Level Types
Tracy Arm; Jingle-Jangle; Neglected Prize Prospect	Prospect
Petersburg Mining District	Mining District
Juneau	City Borough
Alaska	State
USA	Country

The prospect is in the Tracy Arm-Fords Terror Wilderness Area which is closed to prospecting and mining.
Location: The center of the Tracy Arm prospect is at an elevation of about 820 feet, about 0.7 mile south of the southeast point at the elbow of Tracy Army. It is near the center of section 3, T. 46 S., R. 73 E. The mineralization forms a narrow belt that extends at least 800 feet in a south-southeast direction.
Geology: The Jingle Jangle prospect is a narrow band of massive-sulfide mineralization that extends for at least 1,100 feet (Buddington, 1925; Roehm, 1942 [PE 115-1]; Gault and Fellows, 1943; Kimble and others, 1984). The deposit was discovered in 1916 and has been explored by 22 shallow pits and a 16-foot shaft. The deposit is parallel to the foliation of the host rock which is hornblende-plagioclase and hornblende-biotite gneiss which strikes N20-30W and dips nearly vertically. The rocks are part of the Cretaceous biotite-schist unit of Brew and Grybeck (1984). The massive-sulfide layer varies from about 0.5 to 6 feet thick and consists mainly of banded pyrrhotite, sphalerite, and chalcopyrite in a quartz matrix. Kimble and others (1984) collected 17 channel samples across the band along its length. The samples contain 0.2 to 5.7 percent copper and 0.02 to 12.0 percent zinc. The highest grade portion of the band extends for about 300 feet and has an average width of 5.2 feet. The grade of this portion is 1.42 percent copper, 3.42 percent zinc, 0.43 ounce of silver per ton, and 0.008 ounce of gold per ton. Kimble and others (1984) calculated that this portion contained abut 187,000 tons of material with a 'gross in-place value of between $1 million and $10 million' (at 1976 metal values).
Workings: This prospect has been explored by 22 shallow cuts and a 16-foot shaft. In addition, a succession of government geologists have examined the prospect since 1925.
Age: The deposit is a band of mineralization in Cretaceous gneiss; however, the age of the protolith is uncertain.
Reserves: The highest grade portion of the band extends for about 300 feet and has an average width of 5.2 feet. The grade of this portion is 1.42 percent copper, 3.42 percent zinc, 0.43 ounce of silver per ton, and 0.008 ounce of gold per ton. Kimble and others (1984) calculated that this portion contained abut 187, 000 tons of material with a 'gross in-place value of between $1 million and $10 million' at 1976 metal prices.

Commodities (Major) - Ag, Au, Cu, Zn
Development Status: None
Deposit Model: Metamorphosed, volcanogenic massive-sulfide deposit.

Other Databases

Link to USGS - Alaska:	SD018

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References