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  3. Alaska Resource Data File (ARDF)

Unnamed (north of Rainbow Glacier)

Occurrence, Probably inactive

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Commodities and mineralogy

Main commodities Ag; Cu
Other commodities Ba; Co
Ore minerals chalcopyrite; pyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale A-2
Latitude 59.14
Longitude -135.58
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 3,300 feet, 1.3 miles S44W from survey marker 'Bow' on the west shore of Chilkat Inlet. It is in the SW1/4, section 33, T. 31 S., R. 59 E. of the Copper River Meridian. It corresponds to location 93 in Gilbert (1988) which is the approximate center of a group of sample locations with anomalously high metal values.

Geologic setting

Geologic description

Gilbert (1988) describes numerous samples within an area of about 1/2 mile in diameter as being quartz schist, felsic schist, or silicified rock with varying amounts of pyrrhotite, pyrite, and some chalcopyrite. Sample values are as high as 6.3 ppm silver, 1,300 ppm copper, 215 ppm cobalt, and 1,600 ppm barium. The host rocks are mapped by Gilbert (1988) as Paleozoic volcanics. His descriptions of felsic schist and quartz schist suggest a Paleozoic age for the mineralization if the rocks are volcanic. Alternatively, the felsic and quartz schists may be due to silicification and/or alteration related to nearby Cretaceous granodiorite intrusives.
Geologic map unit (-135.581838687906, 59.1396688198706)
Mineral deposit model Unknown. Felsic schists are suggestive of a possible volcanogenic massive sulfide or, perhaps, an alteration zone peripheral to an intrusive.
Age of mineralization Unknown. If the felsic schist that hosts the deposit is volcanic, then the mineralization is probably Paleozoic. If the felsic schists are alteration zones peripheral to an intrusive, then the mineralization is probably related to the nearby Cretaceous intrusive rocks (Gilbert, 1988).
Alteration of deposit Silicification?

Production and reserves

Indication of production None

References

MRDS Number 10308238

References

Gilbert, W.G., 1988, Preliminary geology and geochemistry of the northern Chilkat Range: Alaska Division of Geological and Geophysical Surveys Report of Investigations 88-8, 2 sheets, scale 1:36,200.
Reporters T.C. Crafford (T. Crafford & Associates, Anchorage)
Last report date 2/4/2001