Unnamed Occurrence (ARDF - UM002; on western Tigalda Island), Aleutian Islands Mining District, Aleutians East Borough, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - UM002; on western Tigalda Island)	- not defined -
Aleutian Islands Mining District	Mining District
Aleutians East Borough	Borough
Alaska	State
USA	Country

This site is on lands selected by the Aleut Native Corporation.
Location: This site represents several color anomalies on the west end of the island between Derkin and Kelp Bays. Site location is accurate to within 1 mile.
Geology: This occurrence consists of several color anomalies along a northwest-trending fault which crosses the island between Derkin and Kelp Bays. Rocks in these areas are mostly Tertiary andesites and dacite porphyries which have been intruded by diorite 'bodies' and basalt dikes (Butherus and others, 1979). Within the color anomalies the andesite and diorite are fractured, pyritized, and moderately argillically altered. Quartz-calcite veins, some up to 2 feet thick, are common in the altered and fractured areas. A sample of quartz-calcite vein material collected by Resource Associates of Alaska contained values of up to 85 ppm copper, 1.2 ppm gold, 96 ppm lead, 18.1 ppm silver, and 176 ppm zinc (Butherus and others, 1979). They also reported values to 8700 ppm arsenic, 250 ppm copper, and 7 ppm mercury from an unknown location on the south side of the island. Kennecott collected 15 samples of vein material in 1985 (Simpson, 1986). They reported gold in quantities up to 4.6 ppm.
Workings: Sampling by Resource Associates of Alaska of one vein returned metal values of 85 ppm copper, 1.2 ppm gold, 96 ppm lead, 18.1 ppm silver, and 176 ppm zinc (Butherus and others, 1979). Kennecott collected 15 samples of vein material and reported gold values up to 4.6 ppm (Simpson, 1986).
Age: Tertiary.
Alteration: Country rocks are propylitized, pyritized, and locally argillized.

Commodities (Major) - Ag, Au; (Minor) - Pb, Zn
Development Status: None
Deposit Model: Epithermal gold veins or Creede epithermal veins(?) (Cox and Singer, 1986; mode

Other Databases

Link to USGS - Alaska:	UM002

Other Regions, Features and Areas containing this locality

References