Unnamed (on northern Akun Island)

Prospect, Inactive

Commodities and mineralogy

Main commodities S
Other commodities Cu; Hg; Zn
Ore minerals native sulfur; pyrite

Geographic location

Quadrangle map, 1:250,000-scale UM
Quadrangle map, 1:63,360-scale B-5
Latitude 54.26
Longitude -165.64
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is at elevations between 1,400 and 1,600 feet on the northwest part of Akun Island approximately 0.8 miles northeast of Mt. Gilbert. Site location is accurate to within 1/2 mile.

Geologic setting

Geologic description

Rocks at this site consist of andesitic flows, agglomerates, and tuff breccias which exhibit extreme argillic alteration (Butherus and others, 1979). These rocks are thought to be Tertiary or younger in age (Simpson, 1985). Native sulfur occurs with the altered rock. Several small zones of altered material occur over a 15 to 20 acre area. The main zone of alteration and sulfur mineralization measures approximately 500 by 1200 feet. The altered material varies from dull yellowish earthy masses to to gray pyritic clay. Maddren (1919) describes the surface material as a highly decomposed earthy zone having a thickness of 1 to 4 feet. Below this zone is a 6 to 10 foot layer of seimleached decomposed rock which appears to be massive clay.
A small amount of sulfur commonly occurs as thin encrustations on walls of fractures and cavities. The encrustations are generally less than 1/8 inch thick, but may be up to 1 inch thick. Some sulfur is also present as disseminations in the altered rock. Most of the sulfur occurs within 1 to 4 feet of the surface. Two samples collected in 1917 contained 55.5 and 22.8 percent sulfur (Maddren, 1919). Using an average thickness of 2 feet and a sulfur content of 40 percent, he estimated a total resource of 1200 tons. Bain (1979), however, cites a U.S. Geological Survey estimate of 15,000 to 20,000 tons.
Resource Associates of Alaska examined this area in 1979 and again in 1984, looking primarily for precious metals (Butherus and others, 1979; Butherus, 1984). Three samples collected in 1979 contained up to 270 ppm copper, 7.6 ppm mercury, 16 ppm tungsten, and 260 ppm zinc. No gold was detected. In 1984, sixty-seven samples were collected and all but one were highly anomalous in mercury. A few samples were also anomalous in copper and zinc.
Geologic map unit (-165.641984077522, 54.2591368403863)
Mineral deposit model Solfataric sulfur
Age of mineralization Tertiary or younger.
Alteration of deposit Argillic.

Production and reserves

Workings or exploration
Attempts to mine the sulfur at this site continued off and on from 1917 to at least 1937, as described in various U.S. Geological Survey reports (see following). Maddren (1919) reported that numerous trenches, ranging in depth from 4 to 15 feet had been dug in 1917 and that 2 samples had assayed 55.5 and 22.8 percent sulfur. Martin (1920) reported a test shipment in 1918. Brooks (1921, 1922, and 1923) reported that a commercial deposit of sulfur was being opened up and that equipment for mining and reduction of sulfur was supposed to be in place at the end of 1920. Nothing of consequence was reported until it was announced that in 1930 Pacific Coast Sulfur Company was organized to mine the sulfur with a steam shovel and transport it to the beach using an aerial tram (Smith, 1933). The tram was actually built and the remains of it have been noted by recent workers in the area. In 1935 the prospect was acquired by Alaska Northwest Sulfur Company. No record of any production has been found.
Resource Associates of Alaska examined and sampled the prospect in 1979 and in 1984, looking for precious metals (Butherus and others, 1979; Butherus, 1984). All samples were anomalous in mercury, and a few were anomalous in copper and zinc. No gold was detected.
Indication of production Undetermined
Reserve estimates Estimates of the sulfur resource range from 1,200 tons (Maddren, 1919) to 20,000 tons (Bain, 1979).

Additional comments

This site is on land selected by the Aleut Native Corporation.

References

MRDS Number A013230

References

Butherus, D., 1984, Exploration and evaluation of northern Akun Island and Walrus Peak-Littlejohn areas, Aleut Native Corporation Lands: Resource Associates of Alaska, 14 p. (Report held by the Aleut Native Corporation, Anchorage, Alaska.)
Butherus, D.L, Gressitt, E.E., Pray, J., Corner, N.G., Lindberg, P.H., and Fankhauser, R.E., 1979, Exploration and evaluation of the Aleut Native Corporation lands; Volume III: Resource Associates of Alaska, 69 p. 90 sheets, various sacales. (Report held by the Aleut Native Corporation, Anchorage, Alaska.)
Reporters S.H. Pilcher (Anchorage)
Last report date 1/27/2000