Unnamed (south of Williams Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Gypsum (alabaster)
Ore minerals gypsum

Geographic location

Quadrangle map, 1:250,000-scale NB
Quadrangle map, 1:63,360-scale A-3
Latitude 62.1824
Longitude -142.4105
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on the north flank of the large ridge bordering the south side of the valley of William and Notch Creeks. It is at an elevation of about 6,900 feet, 4,500 feet northeast of peak 8750 and 5,500 feet northwest of peak 7351. The occurrence is about 0.5 mile east-southeast of the center of section 27, T. 5 N., R. 16 E. of the Copper River Meridian. The occurrence is located to within about 1,000 feet.

Geologic setting

Geologic description

Massive pods up to 5 feet thick of the alabaster, a variety of gypsum, occur in amphibolitized, amygdaloidal basalt of the Triassic, Nikolai Greenstone (Richter and Matson, 1969; Richter, 1971 [I-655]; Richter, 1976).
Geologic map unit (-142.412629092409, 62.1820239174806)
Age of mineralization Cretaceous? Alteration and mineralization of the Nikolai Greenstone is thought to have accompanied regional deformation and low-grade metamorphism in the Late Jurassic to Early Cretaceous (MacKevett and others, 1997).
Alteration of deposit Gypsum replacement of metabasalt.

Production and reserves

Indication of production None

Additional comments

The occurrence is in the Wrangell-St. Elias National Preserve.

References

MRDS Number A011438

References

MacKevett, E.M., Jr., Cox, D.P., Potter, R.W., III, and Silberman, M.L., 1997, Kennecott-type deposits in the Wrangell Mountains, Alaska--High-grade copper ores near a basalt-limestone contact, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 66-89.
Reporters Travis L. Hudson (Applied Geology)
Last report date 11/24/2002