Big Mac

Occurrence, Inactive

Commodities and mineralogy

Main commodities Fe
Ore minerals pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-1
Latitude 63.1673
Longitude -144.2298
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Big Mac occurrence is located at an elevation of about 5,700 feet between the head of Rumble Creek and the Tok River. It is approximately 0.4 mile northeast of peak 7725 in the west-central portion of section 14, T. 16 N., R. 6 E., Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The Big Mac occurrence consists of massive pyrite lenses as much as 1 foot thick and semimassive pyrite lenses as much as 10 feet thick; the lenses are in interbedded felsic metavolcanic rocks, pyritic exhalite (?), and minor limestone and graphitic black schist. The mineralized layer or unit can be traced for 1.5 miles along a cliff face; it is covered on the east and west by glacial till and ice. Base and precious metals values are at or below background levels in all samples collected (E. Hunter, unpublished data, 1998). The host rock is probably in the upper Tok River stratigraphic unit, but it is near a facies transition to the Hayes Glacier unit (Dashevsky and others, 2003).
Geologic map unit (-144.232041127126, 63.1669185581952)
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 Big Mac occurrence was visited by American Copper and Nickel Company in 1994. Only background values for base and precious metal were found in the sulfides (E. Hunter, unpublished data, 1998).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The unpublished data that is cited can be seen by contacting Grayd Resources Inc. in Vancouver, B.C., Canada (, or Northern Associates Inc. in Fairbanks, Alaska.