Prospect, Active?

Commodities and mineralogy

Main commodities Cu; Fe
Ore minerals chalcopyrite; magnetite

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale A-2
Latitude 55.24601
Longitude -132.61664
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Gonnason prospect is about 0.7 mile north-northwest of Copper Mountain and about 0.2 mile north-northwest of the southeast corner of section 27, T. 76 S., R. 84 E.

Geologic setting

Geologic description

The Gonnason prospect was found in 1960 by the Hanna Mining Company (Hogg, 1965; Herreid and others, 1978). The deposit consists of a body of magnetite with chalcopyrite in skarn. As exposed on the surface, the body is about 150 by 225 feet in area and of unknown depth. A channel sample about 80 feet long across the deposit averaged 50.6 percent iron and 0.94 percent copper. Hogg (1965) estimated that the deposit is comparable in tonnage and grade to the Magnetite Cliff deposit (CR148). Although the body is in skarn, Kennedy (1953) and Herreid and others (1978) map the rocks in the area only as Cretaceous granodiorite. The deposit is probably in a small roof pendant of skarn in the granodiorite and is similar to the deposits at the nearby Jumbo Mine (CR150) and Magnetite Cliff (CR148).
Geologic map unit (-132.618296067923, 55.2456584748956)
Mineral deposit model Iron-copper skarn (Cox and Singer, 1986; model 18d).
Mineral deposit model number 18d
Age of mineralization Iron-copper skarn probably related to a nearby Cretaceous granodiorite intrusion.
Alteration of deposit Associated with magnetite-bearing skarn.

Production and reserves

Workings or exploration Surface sampling and geophysical surveys.
Indication of production None
Reserve estimates Hogg (1965) estimated that the deposit is comparable in tonnage and grade to the Magnetite Cliff deposit (CR148).

Additional comments

The Gonnason prospect is on a large block of patented claims. The land around it has been conveyed to the Sealaska Corporation or is under application for transfer to them.


MRDS Number A010165


Reporters D.J. Grybeck (Applied Geology)
Last report date 5/1/2004