Tracy Arm

Prospect, Probably inactive

Alternative names

Jingle-Jangle
Neglected Prize

Commodities and mineralogy

Main commodities Ag; Au; Cu; Zn
Ore minerals chalcopyrite; pyrrhotite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SD
Quadrangle map, 1:63,360-scale D-5
Latitude 57.90888
Longitude -133.57038
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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.

Geologic setting

Geologic description

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).
Geologic map unit (-133.572107922247, 57.9085476452517)
Mineral deposit model Metamorphosed, volcanogenic massive-sulfide deposit.
Age of mineralization The deposit is a band of mineralization in Cretaceous gneiss; however, the age of the protolith is uncertain.

Production and reserves

Workings or exploration 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.
Indication of production None
Reserve estimates 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.

Additional comments

The prospect is in the Tracy Arm-Fords Terror Wilderness Area which is closed to prospecting and mining.

References

MRDS Number A013326; D002180

References

Newberry, R.J., Crafford, T.C., Newkirk, S.R., Young, L.E., Nelson, S.W., and Duke, N.A., 1997, Volcanogenic massive sulfide deposits of Alaska, in Goldfarb, R.J. and Miller, L. D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 120-150.
Reporters Donald Grybeck (U.S. Geological Survey)
Last report date 10/8/2004