Mullen (ARDF #VA044) Cu

Mullen

Prospect, Inactive

Commodities and mineralogy

Main commodities	Cu
Other commodities	Ag; Au
Ore minerals	azurite; bornite; chalcocite; chalcopyrite; covellite; limonite; malachite; pyrite
Gangue minerals	calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale	VA
Quadrangle map, 1:63,360-scale	C-1
Latitude	61.6783
Longitude	-144.0671
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This prospect is adjacent to or very near the Ammann prospect (VA045), which is on the divide between upper Copper Creek and an unnamed (unmapped) west tributary (Van Alstine and Black, 1946, plate 30). The prospect is at an elevation of about 3,800 feet in the SW1/4 section 24, T. 2 S., R. 7 E., of the Copper River Meridian. This prospect is approximately located, perhaps to within one-quarter mile. It is included in locality 70 of Cobb and Matson (1972) and locality 57 of Winkler and others (1981 [OFR 80-892-B]). Cobb (1979 [OFR 79-1241]) includes this prospect under the name 'Mullen'.

Geologic setting

Geologic description Mineralized northeast-trending fault zones cut Triassic Nikolai Greenstone and Chitistone Limestone at the Mullen prospect (Van Alstine and Black, 1946). Mineralization consists of calcite or quartz-calcite veins with copper-bearing minerals. The mineralized veins contain various amounts of bornite, chalcocite, chalcopyrite, covellite, and pyrite; secondary minerals include azurite, malachite, and limonite. In places, the copper-bearing minerals form small irregular pods in the fault zones. The veins range from 1 to 12 inches in thickness and have been traced in underground workings for as much as a few tens of feet of strike length. A 5-foot channel sample contained 1.55 percent copper, and a 4-foot channel sample contained 5.82 percent copper, 0.28 ounces of silver per ton, and a trace of gold. The underground workings at the Mullen prospect consisted of two adits, short cross cuts and drifts, and two declines that have a total length of at least 800 feet (Van Alstine and Black, 1946). Small, altered diorite intrusive bodies are present at the contact between Nikolai Greenstone and Chitistone Limestone. The copper mineralization is believed to be related to the regional mineralizing event that produced the rich Kennecott copper deposits in the McCarthy quadrangle (MacKevett and others, 1997).
Geologic map unit	(-144.069195758506, 61.6778342413307)
Mineral deposit model	Vein and fracture fillings in greenstone and limestone; probably related to Kennecott-type copper deposits (MacKevett and others, 1997)
Age of mineralization	The copper mineralization is believed to be related to the mineralizing event that produced the rich Kennecott copper deposits in the McCarthy quadrangle to the east (MacKevett and others, 1997). This event is interpreted to have accompanied Late Jurassic or Early Cretaceous deformation and metamorphism (MacKevett and others, 1997, p. 88).
Alteration of deposit	The diorite bodies are altered to a combination of chlorite, calcite, talc, leucoxene, quartz and pyrite (Van Alstine and Black, 1946).

Production and reserves

Workings or exploration	The Mullen prospect was explored by three open cuts, two adits, short cross cuts and drifts, and two declines that have a total length of at least 800 feet (Van Alstine and Black, 1946).
Indication of production	None
Additional comments This prospect is within the Wrangell-St. Elias National Park.

References

MRDS Number	A011513
References Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Valdez quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1241, 167 p. Cobb, E.H., and Matson, N.A., Jr., 1972, Metallic mineral resources map of the Valdez quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-438, 1 sheet, scale 1:250,000. 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. Van Alstine, R.E., and Black, R.F., 1946, Copper deposits of the Kotsina-Kuskulana district, Alaska: U.S. Geological Survey Bulletin 947-G, p. 121-141. Winkler, G.R., Miller, R.J., MacKevett, E.M., Jr., and Holloway, C.D., 1981, Map and summary table describing mineral deposits in the Valdez quadrangle, southern Alaska: U.S. Geological Survey Open-File Report 80-892-B, 2 sheets, scale l:250,000.
Reporters	Travis L. Hudson
Last report date	12/14/2001