Alaska Resource Data File 

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic code. Any use 

of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

OPEN-FILE REPORT 00-117 

Unimak Island

o

o

o

o o

o

o

o

 Distribution of mineral occurrences in the Unimak

1:250,000-scale quadrangle, Aleutian Islands, Alaska

 This and related reports are accessible through the USGS World Wide Web site 

http://ardf.wr.usgs.gov. Comments or information regarding corrections or missing 

data, or requests for digital retrievals should be directed to: Frederic Wilson, USGS, 4200 

University Dr., Anchorage, AK 99508-4667, e-mail fwilson@usgs.gov, telephone (907) 

786-7448. This compilation is authored by:

 Steven H. Pilcher

 Anchorage, AK

Unimak quadrangle

 Descriptions of the mineral occurrences shown on the accompanying figure follow. 

See U.S. Geological Survey (1996) for a description of the information content of each field 

in the records. The data presented here are maintained as part of a statewide database 

on mines, prospects and mineral occurrences throughout Alaska.
Alaska Resource Data File 

Page 2 

Site name(s): Unnamed (on western Rootok Island) 

Site type: Occurrence 

ARDF no.: UM001 

Latitude: 54.042 Quadrangle: UM A-5 

Longitude: 165.561 

Location description and accuracy:

 This site, anomaly 42 of Christie (1974), is located on the westernmost part of Rootok 

Island approximately 1/2 mile east of VABM Root. This location is accurate to within 

500 feet. 

Commodities: 

 Main: Ag, Au, Cu 

 Other: Mo, Zn 

Ore minerals: Chalcocite, chalcopyrite, malachite, pyrite 

Gangue minerals: Quartz, tourmaline 

Geologic description:

 At this site the rocks consist of amygdoidal and porphyritic andesites of probable Tertiary or later age. They are cut by diorite dikes or plugs (Christie, 1974). All of the intrusive 

rocks examined contained pyrite as disseminations and fracture fillings. This occurrence 

consists of a northern and a southern color anomaly separated by a covered area approximately 1000 feet wide. 

 In the northern area copper minerals occur along a north-facing sea cliff irregularly for 

800 feet. The minerals are mainly malachite and minor chalcopyrite and chalcocite, and 

are sporadically distributed throughout the area. The minerals are mainly in breccia bodies, up to 60 feet in width, consisting of angular and rotated fragments of quartz-sericitepyrite in a matrix of comminuted fragments and iron oxides. Malachite is present both in 

the fragments and matrix. One breccia contains 1 to 2 percent tourmaline. Wall rock 

around the breccias varies from pyritiferous volcanics to malachite-chalcopyritechalcocite-bearing diorite. The quartz-sericite-pyrite alteration grades outward to pervasive propylitization marked by epidote and pyrite. 

 The southern color anomaly exhibits pervasive propylitic alteration which grades southward to unaltered volcanics over distance of approximately 3000 feet. 

 Seventeen rock samples collected by the Aleut-Quintana-Duval JV contained up to 159 

ppm copper, 0.46 ppm gold, 6 ppm molybdenum, 2.2 ppm silver, and 120 ppm zinc 

(Christie, 1974). 

UM001 
Alaska Resource Data File 

Page 3 

 In 1975 Christie (1976) returned to this site and collected soils and silts and conducted a 

magnetometer survey of the covered area. This examination revealed strongly altered, biotite-bearing rock containing widely-spaced quartz veins. This material contained up to 

790 ppm copper and 0.04 ppm gold. 

Alteration:

 The rocks exhibit pervasive propylitic alteration consisting of chlorite, epidote, and pyrite. The breccia bodies in the northern area are altered to quartz-sericite-pyrite. Wall rock 

adjoining the breccias varies from pyritized volcanics to malachite-chalcopyritechalcopyrite-bearing porphyritic diorite, whose feldspar phenocrysts are altered to clay. 

Age of mineralization:

Probably Tertiary. 

Deposit model:

Porphyry copper (Cox and Singer, 1986; model 17) 

Deposit model number (After Cox and Singer, 1986 or Bliss, 1992):

17 

Production Status: None 

Site Status: Inactive 

Workings/exploration:

 Christie (1974) conducted reconnaissance geologic mapping and limited sampling. 

That sampling generally indicated low values of copper and molybdenum and gold values 

as high as 0.46 ppm and silver values as high 2.2 ppm. Zinc values were moderately 

anomalous: a number of samples yielded values in the range of 90 to 120 ppm. Although 

Christie (1974) mentions copper values up to 0.25 percent, his sample data does not support this. 

 Christie (1976) did some additional work in the covered area in 1975, but concluded the 

area was not worth drilling. 

Production notes:

 

Reserves:

 

Additional comments:

 This site is on land patented by or conveyed to the Aleut Native Corporation. 

References:

Christie, 1974; Christie, 1976. 

Primary reference: Christie, 1974 

UM001 
Alaska Resource Data File 

Page 4 

Reporter(s): S.H. Pilcher (Anchorage) 

Last report date: 1/27/00 

UM001 
Alaska Resource Data File 

Page 5 

Site name(s): Unnamed (on western Tigalda Island) 

Site type: Occurrence 

ARDF no.: UM002 

Latitude: 54.11 Quadrangle: UM A-4 

Longitude: 165.14 

Location description and accuracy:

 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. 

Commodities: 

 Main: Ag, Au 

 Other: Pb, Zn 

Ore minerals: Gold, pyrite 

Gangue minerals: Calcite, quartz 

Geologic description:

 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. 

Alteration:

 Country rocks are propylitized, pyritized, and locally argillized. 

Age of mineralization:

Tertiary. 

Deposit model:

UM002 
Alaska Resource Data File 

Page 6 

Epithermal gold veins or Creede epithermal veins(?) (Cox and Singer, 1986; model 25b) 

Deposit model number (After Cox and Singer, 1986 or Bliss, 1992):

25b? 

Production Status: None 

Site Status: Inactive 

Workings/exploration:

 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). 

Production notes:

 

Reserves:

 

Additional comments:

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

References:

Butherus and others, 1979; Simpson, 1986; Randolph, 1990. 

Primary reference: Butherus and others, 1979 

Reporter(s): S.H. Pilcher (Anchorage) 

Last report date: 1/27/00 

UM002 
Alaska Resource Data File 

Page 7 

Site name(s): Unnamed (on shore of Trident Bay) 

Site type: Occurrence 

ARDF no.: UM003 

Latitude: 54.141 Quadrangle: UM A-5 

Longitude: 165.557 

Location description and accuracy:

 This site, color anomaly 43 of Christie (1974), is located on the southeast coast of Akun 

Island. The occurrence is on the north and south shores of the southwest arm of Trident 

Bay. Site location is accurate to within 500 feet. 

Commodities: 

 Main: Fe 

 Other: 

Ore minerals: Pyrite 

Gangue minerals: 

Geologic description:

 This occurrence represents a color anomaly which is approximately 1,500 by 200 feet 

(Christie, 1974). Rocks at this site include andesite, vescicular andesite, feldspar porphyry, basalt, tuff, and conglomerate. The volcanic rocks are of probable Tertiary age 

(Christie, 1974; Simpson, 1985). The primary feldspars have been partially altered to clay 

and epidote. Strong gossan occurs along the north shore of the southwest arm at Trident 

Bay. Extensions of this gossan may be covered by the conglomerate. A weak gossan is 

present along the south shore of this arm of the bay. The altered rocks contain 1 to 4 percent pyrite, with only a minor amount of which occurs as fracture fillings. 

 The Aleut-Quintana-Duval JV collected 5 silt and 2 soil samples at this site in 1974 

(Christie, 1974). No anomalous metal values were detected. 

Alteration:

 Primary volcanic feldspars are partly altered to clay and epidote. 

Age of mineralization:

Tertiary or younger. 

Deposit model:

 

UM003 
Alaska Resource Data File 

Page 8 

Deposit model number (After Cox and Singer, 1986 or Bliss, 1992):

 

Production Status: None 

Site Status: Inactive 

Workings/exploration:

 The Aleut-Quintana-Duval JV briefly examined the site and collected a few silt and soil 

samples in 1974 (Christie, 1974). No anomalous metal values were detected. 

Production notes:

 

Reserves:

 

Additional comments:

 This site is on lands patented or conveyed to the Aleut Native Corporation. 

References:

Christie, 1974. 

Primary reference: Christie, 1974 

Reporter(s): S.H. Pilcher (Anchorage) 

Last report date: 1/27/00 

UM003 
Alaska Resource Data File 

Page 9 

Site name(s): Unnamed (on northern Akun Island) 

Site type: Prospect 

ARDF no.: UM004 

Latitude: 54.26 Quadrangle: UM B-5 

Longitude: 165.64 

Location description 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. 

Commodities: 

 Main: S 

 Other: Cu, Hg, Zn 

Ore minerals: Native sulfur, pyrite 

Gangue minerals: 

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, 

UM004 
Alaska Resource Data File 

Page 10 

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. 

Alteration:

 Argillic. 

Age of mineralization:

Tertiary or younger. 

Deposit model:

Solfataric sulfur 

Deposit model number (After Cox and Singer, 1986 or Bliss, 1992):

 

Production Status: Undetermined. 

Site Status: Inactive 

Workings/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. 

Production notes:

 

Reserves:

 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. 

UM004 
Alaska Resource Data File 

Page 11 

References:

Maddren, 1919; Martin, 1920; Brooks, 1921; Brooks, 1922; Brooks, 1923; Brooks and 

Martin, 1921; Brooks and Capps, 1924; Smith, 1933; Smith, 1933; Smith, 1934; Smith, 

1937; Bain, 1979; Cobb, 1980 (OFR 80-909); Butherus and others, 1979; Butherus, 1984. 

Primary reference: Maddren, 1919 

Reporter(s): S.H. Pilcher (Anchorage) 

Last report date: 1/27/00 

UM004 
Alaska Resource Data File 

Page 12 

 References 

Bain, E.H., 1979, Alaska minerals as a basis for industry: U.S. Bureau of Mines Information Circular 7379, 89 p. 

Brooks, A.H., 1921, The future of Alaska mining: U.S. Geological Survey Bulletin 714, p. 5-57. 

Brooks, A.H., 1922, The Alaska mining industry in 1920: U.S, Geological Survey Bulletin 722, p. 1-74. 

Brooks, A.H., 1923, The Alaska mining industry in 1921: U.S. Geological Survey Bulletin 739, p. 1-50. 

Brooks, A.H., and Capps, S.R., 1924, The Alaska mining industry in 1922: U.S. Geological Survey Bulletin 755, 

p. 1-56. 

Brooks, A.H., and Martin, G.C., 1921, The Alaskan mining industry in 1919: U.S. Geological Survey Bulletin 

714, p. 59-95. 

Butherus, D., 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. 

(held by the Aleut Native Corporation, Anchorage, Alaska). 

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. (held by the Aleut Native Corporation, 

Anchorage, Alaska). 

Christie, J.S., 1974, Aleut-Quintana-Duval joint venture final report, 1974, 24 p. (held by the Aleut Native Corporation, Anchorage, Alaska). 

Christie, J.S., 1976, Aleut-Quintana-Duval joint venture final report 1975, 20 p. (held by the Aleut Native Corporation, Anchorage, Alaska). 

Cobb, E.H., and Kachadoorian, R., 1961, Index of metallic and non- metallic mineral deposits of Alaska compiled from published reports of federal and state agencies through 1957: U.S. Geological Survey Bulletin 1139, 336 p. 

Cobb, E.H., 1980, Summaries of data on and lists of references to metallic and selected non-metallic mineral deposits in fifteen quadrangles in southwestern and west-central Alaska: U.S. Geological Survey Open-File 

Report 80-909, 103 p. 

Cox, D.P., and Singer, D.A., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1696, 379 p. 

Maddren, A.G., 1919, Sulfur on Unalaska and Akun Islands and Near Stepovak Bay: U.S. Geological Survey 

Bulletin 692, p. 283-298. 

Martin, G.C., 1920, The Alaska mining industry in 1918: U.S. Geological Survey Bulletin 712, p. 1-52. 

Randolph, D.B., 1990, Unalaska 1990 final report: Battle Mountain Exploration Company, 72 p. (held by the 

Aleut Native Corporation, Anchorage, Alaska). 

Ransome, A.L., and Kerns, W.H., 1954, Names and definitions of regions, districts, and subdivisions in Alaska: 

U.S. Bureau of Mines Information Circular 7679, 91 p. 

Roberts, P., 1974, The economic potential of selected mineral occurrences on Umnak, Unimak, and Sedanka Islands, Aleutian Islands, Alaska: Teck Corporation Limited, 30 p. (held by the Aleut Native Corporation, 

Anchorage, Alaska). 

References 
Alaska Resource Data File 

Page 13 

Simpson, D.F., 1986, Aleutian Islands project, 1985 final report: Kennicott Alaska Exploration Company, 54 p. (held by the Aleut Native Corporation, Anchorage, Alaska). 

Smith, P.S., 1933, The mining industry of Alaska in 1930: U.S. Geological Survey Bulletin 836, p. 1-83. 

Smith, P.S., 1934, The mining industry of Alaska in 1932: U.S. Geological Survey Bulletin 857, p. 1-76. 

Smith, P.S., 1937, The mining industry of Alaska in 1935: U.S. Geological Survey Bulletin 880, p. 1-88. 

References