Unnamed (at head of Limestone Creek)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; As; Au; Cu; Ni; Pd; Sb
Ore minerals chalcopyrite

Geographic location

Quadrangle map, 1:250,000-scale CH
Quadrangle map, 1:63,360-scale C-5
Latitude 67.6043
Longitude -149.3897
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at the head of Limestone Creek, a tributary of the Bettles River. It is about 0.8 mile southeast of peak 4570, about 0.6 mile northwest of the center of section 17, T. 32 N., R. 8 W. The location is accurate to a quarter of a mile.

Geologic setting

Geologic description

Nickel, palladium, and silver were reported in an X-ray analysis of rock from a thrust sheet in Devonian or Silurian, Skajit Limestone (Brosgé and Reiser, 1964). The occurrence is in a section of Skajit Limestone that has overridden Devonian(?) quartz muscovite schist along a major northeast-trending thrust fault. A later examination of the occurrence by Foley and others (1989) found no evidence of anomalous nickel, palladium, and silver in their sample, nor did Kurtak and others (2002).
However, in their search for mineralization in the area, Kurtak and others (2002) found marble in outcrop nearby with 1 to 2 percent sulfides; a sample contained 1.3 parts per million (ppm) silver and 142 ppm arsenic. A float sample of marble with chalcopyrite was found about 1.5 miles upstream from the mouth of Limestone Creek; a sample contained 77 parts per billion gold, 3.3 ppm silver, 1.41 percent copper, and 109 ppm antimony.
Geologic map unit (-149.39245471131, 67.6038952798297)
Mineral deposit model Chalcopyrite in marble with low silver, gold, arsenic, and antimony values.
Age of mineralization Silurian or younger based on the age of the marble host rock.
Alteration of deposit Not specified.

Production and reserves

Workings or exploration Only sampling by government agencies.
Indication of production None
Reserve estimates None.
Production notes None.

Additional comments

This prospect is on Doyon Ltd. selected lands; for more information, contact Doyon Ltd., Fairbanks, Alaska.
MAS No. 0020310139


MRDS Number A012144


Reporters J.M. Britton (Anchorage, Alaska); D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/18/2010