ED (ARDF #MH322) Cu, Zn

ED

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Cu; Zn
Other commodities	Pb
Ore minerals	chalcopyrite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals	quartz

Geographic location

Quadrangle map, 1:250,000-scale	MH
Quadrangle map, 1:63,360-scale	A-1
Latitude	63.1722
Longitude	-144.2923
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	The ED occurrence is on the east side of the glacier at the head of Rumble Creek and at an elevation of about 4,700 feet. The occurrence is 1.2 miles east-southeast of peak 6705 and in the NW1/4 section 16, T. 16 N., R. 6 E., Copper River Meridian. The location is accurate.

Geologic setting

Geologic description The ED occurrence consists of semimassive to massive pyrite, pyrrhotite, and chalcopyrite that occur as pods and lenses as much as 1 foot thick along the contact of felsic metavolcanic schists and marble. The felsic volcanic unit or layer can be traced for 3 miles before it is covered by talus and ice both to the east and west. At the west end the mineralized layer is less than 10 feet thick (E. Hunter, unpublished data, 1998). The ED prospect was sampled by American Copper and Nickel Company in 1994. The highest grade sample contains 3,631 parts per million (ppm) copper, 180 ppm lead, 292 ppm zinc, 2.4 ppm silver, and 5 parts per billion (ppb) gold (E. Hunter, unpublished data, 1998). Other samples collected from talus float contain as much as 1.2 percent copper, 1.8 percent lead, 2.7 percent zinc, 28 ppm silver, and 85 ppb gold (S.S. Dashevsky, written communication, 2003). The ED occurrence is in the upper Tok River unit near the facies transition to the Hayes Glacier unit (Dashevsky and others, 2003).
Geologic map unit	(-144.294540423774, 63.171817600315)
Mineral deposit model	Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number	28a
Age of mineralization	Devonian to Mississippian, on the basis of the age of the host rocks.

Production and reserves

Workings or exploration	The ED prospect has only had limited surface sampling by American Copper and Nickel Company in 1994 (E. Hunter, unpublished data, 1998).
Indication of production	None
Additional comments The unpublished data that is cited can be seen by contacting Grayd Resources Inc. in Vancouver, B.C., Canada (www.grayd.com), or Northern Associates Inc. in Fairbanks, Alaska.

References

References Dashevsky, S.S., Schaefer, C.F., and Hunter, E.N., 2003, Bedrock geologic map of the Delta mineral belt, Tok mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 122, 2 sheets, scale 1:63,360.
Reporters	W.T. Ellis (Alaska Earth Sciences) and A.W. Wyatt and S.S. Dashevsky (Northern Associates Inc.)
Last report date	3/20/2003