Diamond Point

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu
Other commodities Sn
Ore minerals pyrite

Geographic location

Quadrangle map, 1:250,000-scale IL
Quadrangle map, 1:63,360-scale C-2
Latitude 59.6447
Longitude -153.6294
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is near sea level on Diamond Point between Cottonwood and Iliamna Bays. The location is probably accurate within 1,000 feet; it corresponds to number 8 of Detterman and Cobb (1972).

Geologic setting

Geologic description

The country rocks in the area of Diamond Point include Jurassic quartz monzonite, andesite of the Jurassic Talkeetna Formation, and undivided Tertiary(?) volcanic rocks (Detterman and Reed, 1980). The contact between the quartz monzonite and the andesite is steep and strikes north-northeast. It is roughly parallel to a fault that separates the Talkeetna Formation from basalt of the Triassic Cottonwood Bay Formation.
Martin and Katz (1912) described an 8- to 12-foot-wide shear zone on the Iliamna Bay side of the prospect and about a 100-foot-wide shear zone on the Cottonwood Bay side. The 100-foot-wide zone contains narrow veins and stringers of pyrite. Martin and Katz (1910, 1912) reported that rocks assayed privately contained about 0.1 ounce of gold per ton. Detterman and Reed (1964) characterized the occurrence at Diamond Point as an association of gold, silver, and copper along with other metals. Their sample 118, collected on or near Diamond Point, contained 100 parts per million (ppm) copper and 15 ppm tin. Samples that they collected to the north on Iliamna Bay (nos. 122 &123) contained 150 ppm copper and as much as 20 ppm tin.
Geologic map unit (-153.631650039371, 59.6440727038307)
Mineral deposit model Polymetallic vein? (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c?
Age of mineralization Probably Jurassic.

Production and reserves

Workings or exploration At least one claim was staked on Diamond Point on or before 1909 (Martin and Katz, 1910). It may have been prospected with shallow pits and trenches which are no longer visible. Detterman and Reed (1964) recognized mineralization in the area, but appear to have collected only one sample (no. 118) at or near the original prospect site.
Indication of production None