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 00-120 

Sutwik Island

Semidi Islands Alaska Peninsula

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 Distribution of mineral occurrences in the Sutwik Island

1:250,000-scale quadrangle, Alaska Peninsula, 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

Sutwik Island 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 Cape Kumlik) 

Site type: Occurrence 

ARDF no.: SW001 

Latitude: 56.63 Quadrangle: SW C-5 

Longitude: 157.48 

Location description and accuracy:

 This occurrence is located on the east coast of the mainland between Kujulik and Aniakchak Bays. The map site is about 1 mile inland from the easternmost tip of Cape Kumlik (MacKevett and Holloway, 1977, localities 3 and 7; Cox and others, 1981, locality 1). 

The site location is accurate to within 1/2 mile. 

Commodities: 

 Main: Cu 

 Other: Ag, Au, Mo 

Ore minerals: Chalcopyrite, molybdenite?, pyrite 

Gangue minerals: Quartz?, barite? 

Geologic description:

 At this site a quartz diorite stock has intruded volcanic rocks of the Oligocene and Eocene Meshik Formation (Detterman and others, 1981). The occurrence is marked by a 

large color anomaly covering about 1 section. Chalcopyrite and pyrite occur in quartz(?) 

veinlets and as disseminations in both the intrusive and in the surrounding volcanic rocks 

(Hedderly-Smith, 1977). Barite has been noted in many stream-sediment samples. 

 Numerous rock-chip samples collected by Bear Creek Mining Company returned copper values in the 400 ppm to 1000 ppm range and several contained 1000 ppm to 2000 

ppm copper (Hedderly-Smith, 1977). The highest value was 5600 ppm copper from a 

sample of the mineralized intrusive. Molybdenum and silver were indicated as low-order 

anomalies. Gold was detected in the 0.07ppm 0.31 ppm range. The higher gold values 

generally coincided with the higher copper values. Of 7 rock samples collected here in 

1978 by the U.S. Geological Survey, only 1 contained strongly anomalous values in copper (2200 ppm) (Yount and others, 1978). Cox and others (1981) estimate a small tonnage of low grade mineralization. 

 The rocks at the center of the mineralized area exhibit potassic alteration (HedderlySmith, 1977). Quartz-sericite alteration and silicification occur to the east, south, and 

west of the central area in both intrusive and volcanic rocks. An outer zone of propylitization is present. 

SW001 
Alaska Resource Data File 

Page 3 

Alteration:

 The rocks exhibit a zoned alteration pattern, with a central potassic core grading outward to quartz-sericite and silicification, and to peripheral propylitization. 

Age of mineralization:

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:

 Resource Associates of Alaska did a stream-sediment geochemical survey in 1975 

(Hedderly-Smith, 1977). Bear Creek Mining Company geochemically sampled and 

mapped the occurrence in 1977 (Hedderly-Smith, 1977). Most samples returned copper 

values in the 400 to 1000 ppm range. One sample of mineralized intrusive contained 5600 

ppm copper. Low order molybdenum and silver anomalies were also detected. The U.S. 

Geological Survey (Yount and others, 1978) took 7 samples in 1978. The highest copper 

value obtained was 2200 ppm. 

Production notes:

 

Reserves:

 This occurrence is estimated to have a small tonnage of low grade (Cox and others, 

1981). 

Additional comments:

 This site is located on land selected by the Koniag Native Corporation. 

References:

MacKevett and Holloway, 1977; Hedderly-Smith, 1977; Yount and others, 1978; Cox and 

others, 1981; Detterman and others, 1981. 

Primary reference: Hedderly-Smith, 1977 

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

Last report date: 1/31/00 

SW001 
Alaska Resource Data File 

Page 4 

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

Site type: Prospect 

ARDF no.: SW002 

Latitude: 56.34 Quadrangle: SW B-6 

Longitude: 157.88 

Location description and accuracy:

 This site is on the western part of Nakchamik Island which is located approximately 10 

miles south of Cape Kumliun in Chignik Bay (MacKevett and Holloway, 1977, locality 8; 

Cox and others, 1981, locality 5). Site location is at an elevation of about 700 feet and is 

accurate to within 1/2 mile. 

Commodities: 

 Main: Cu 

 Other: Pb, Zn 

Ore minerals: Chalcopyrite, galena?, pyrite, sphalerite? 

Gangue minerals: Quartz?, barite? 

Geologic description:

 On Nakchamik Island, dacite plug domes intrude Oligocene and Eocene volcanic rocks 

of the Meshik Formation (Detterman and others, 1981). The prospect is marked by a 

large color anomaly. Closely-spaced quartz(?) veinlets containing abundant pyrite and 

chalcopyrite have been noted. Stream-sediment samples contain anomalous values in copper, lead, silver, and zinc and many contain barite. Cox and others (1981) report the grade 

of surface samples at <0.2 percent copper. Sixteen rock samples were collected in the 

1970's by the U.S. Geological Survey (Yount and others, 1978). The highest values obtained were 1600 ppm copper, 130 ppm lead, and 260 ppm zinc. 

Alteration:

 Country rocks are propylitically and sericitically altered. The area is marked by a large 

color anomaly. 

Age of mineralization:

Tertiary. 

Deposit model:

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

SW002 
Alaska Resource Data File 

Page 5 

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

17 

Production Status: None 

Site Status: Inactive 

Workings/exploration:

 Remnants of old mining equipment have been found at this prospect, indicating early 

exploration. The U.S. Geological Survey collected 16 rock samples in the 1970's (Yount 

and others, 1978). The highest metal values obtained were 1600 ppm copper, 130 ppm 

lead, and 260 ppm zinc. Cox and others (1981) report surface copper values at <0.2 percent. 

Production notes:

 

Reserves:

 

Additional comments:

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

References:

Yount and others, 1978; Wilson, 1980; Cox and others, 1981; Detterman and others, 

1981; Young and others, 1997. 

Primary reference: Cox and others, 1981 

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

Last report date: 1/31/00 

SW002 
Alaska Resource Data File 

Page 6 

Site name(s): Unnamed (southeast Nakchamik Island) 

Site type: Occurrence 

ARDF no.: SW003 

Latitude: 56.32 Quadrangle: SW B-6 

Longitude: 157.82 

Location description and accuracy:

 This site is located near the southeast coast of Nakchamik Island (MacKevett and Holloway, 1977, locality 1). The island is approximately 10 miles south of Cape Kumliun in 

Chignik Bay. Site location is accurate to within 1 mile. 

Commodities: 

 Main: Cu 

 Other: 

Ore minerals: Chalcopyrite?, pyrite? 

Gangue minerals: Quartz? 

Geologic description:

 This site is marked by a color anomaly which coincides with a dacite plug dome that 

has intruded volcanics of the Oligocene and Eocene Meshik Formation (Detterman and 

others, 1981; Cox and others, 1981). This mineral occurrence has been described as a porphyry copper deposit consisting of disseminated sulfides in strongly altered intrusive and 

surrounding volcanic rocks (MacKevett and Holloway, 1977). No mention is made of ore 

or gangue minerals present. 

Alteration:

 The alteration is unknown but probably includes propylitic and sericitic types. 

Age of mineralization:

Tertiary. 

Deposit model:

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

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

17 

SW003 
Alaska Resource Data File 

Page 7 

Production Status: None 

Site Status: Inactive 

Workings/exploration:

 Apparently this occurrence has had post-1950 activity (U.S. Bureau of Mines, 1973). 

Production notes:

 

Reserves:

 

Additional comments:

 This site is located on land selected by the Koniag Native Corporation. 

References:

U.S. Bureau of Mines, 1973; MacKevett and Holloway, 1977; Cox and others, 1981; Detterman and others, 1981. 

Primary reference: MacKevett and Holloway, 1977 

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

Last report date: 1/31/00 

SW003 
Alaska Resource Data File 

Page 8 

Site name(s): Unnamed (east tip of Sutwik Island) 

Site type: Occurrence 

ARDF no.: SW004 

Latitude: 56.5 Quadrangle: SW C-4 

Longitude: 156.9 

Location description and accuracy:

 This site is located on the eastern tip of Sutwik Island near Foggy Cape (MacKevett and 

Holloway, 1977, locality 6). Site location is accurate to within 2 miles. 

Commodities: 

 Main: Cu? 

 Other: 

Ore minerals: Chalcopyrite?, pyrite? 

Gangue minerals: Quartz? 

Geologic description:

 The rocks at this site consist of basaltic plug domes intruding sedimentary strata of the 

Meshik Formation (Detterman and others, 1981). The site has been described as a porphyry-type occurrence consisting of a strongly altered zone in Tertiary hypabyssal and 

volcanic rocks (MacKevett and Holloway, 1977). No mention is made of ore or gangue 

minerals present. 

Alteration:

 The alteration is unknown but it probably includes propylitic and sericitic types. 

Age of mineralization:

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 

SW004 
Alaska Resource Data File 

Page 9 

Site Status: Inactive 

Workings/exploration:

 

Production notes:

 

Reserves:

 

Additional comments:

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

References:

MacKevett and Holloway, 1977; Cox and others, 1981; Detterman and others, 1981. 

Primary reference: MacKevett and Holloway, 1977 

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

Last report date: 1/31/00 

SW004 
Alaska Resource Data File 

Page 10 

Site name(s): Unnamed (on Aniakchak River) 

Site type: Prospect 

ARDF no.: SW005 

Latitude: 56.8 Quadrangle: SW D-5 

Longitude: 157.6 

Location description and accuracy:

 This site represents placer claims located on the Aniakchak River approximately 3 

miles upstream from Aniakchak Bay (MacKevett and Holloway, 1977, locality 2). Site 

location is accurate to within 3 miles. 

Commodities: 

 Main: Au 

 Other: 

Ore minerals: Gold 

Gangue minerals: 

Geologic description:

 This site represents gold placer claims shown on 1973 U.S. Bureau of Mines maps. 

Alteration:

 

Age of mineralization:

Quaternary. 

Deposit model:

Placer gold-PGE (Cox and Singer, 1986, model 39a) 

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

39a 

Production Status: Undetermined. 

Site Status: Inactive 

Workings/exploration:

 

SW005 
Alaska Resource Data File 

Page 11 

Production notes:

 

Reserves:

 

Additional comments:

 This site is located within the Aniakchak National Monument and Preserve. 

References:

U.S. Bureau of Mines, 1973; MacKevett and Holloway, 1977. 

Primary reference: U.S. Bureau of Mines, 1973 

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

Last report date: 1/31/00 

SW005 
Alaska Resource Data File 

Page 12 

Site name(s): Unnamed (east of Yantarni Creek) 

Site type: Occurrence 

ARDF no.: SW006 

Latitude: 56.9 Quadrangle: SW D-4 

Longitude: 157.3 

Location description and accuracy:

 This occurrence is in T. 37 S., R. 50 W., of the Seward Meridian, east of Yantarni 

Creek (MacKevett and Holloway, 1977, locality 5). Site location is accurate to within 2 

miles. 

Commodities: 

 Main: Cu? 

 Other: 

Ore minerals: Chalcopyrite?, pyrite? 

Gangue minerals: Quartz? 

Geologic description:

 This site is marked by a color anomaly which coincides with a diorite stock (Detterman 

and others, 1981; Cox and others 1981). The stock, dated at 32-40 million years, intrudes 

the Jurassic Naknek and the Eocene and Paleocene Tolstoi Formations (Detterman and 

others, 1981). The diorite is reported to be altered and to contain disseminated porphyrytype mineralization (MacKevett and Holloway, 1977). The main drainage in the area is 

anomalous in zinc (Cox and others, 1981). No mention is made of ore or gangue minerals. 

Alteration:

 Color anomaly associated with diorite stock. 

Age of mineralization:

Tertiary. 

Deposit model:

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

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

17 

SW006 
Alaska Resource Data File 

Page 13 

Production Status: None 

Site Status: Inactive 

Workings/exploration:

 

Production notes:

 

Reserves:

 

Additional comments:

 This site is located on land selected by the Koniag Native Corporation. 

References:

MacKevett and Holloway, 1977; Cox and others, 1981; Detterman and others, 1981. 

Primary reference: MacKevett and Holloway, 1977 

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

Last report date: 1/31/00 

SW006 
Alaska Resource Data File 

Page 14 

Site name(s): Unnamed (on Unavikshak Island) 

Site type: Occurrence 

ARDF no.: SW007 

Latitude: 56.49 Quadrangle: SW B-6 

Longitude: 157.72 

Location description and accuracy:

 This occurrence is located on Unavikshak Island which is approximately 5 miles east of 

Cape Kumliun. No specific sites are described, however the location as plotted is accurate 

to within 1 mile. 

Commodities: 

 Main: Cu? 

 Other: 

Ore minerals: Chalcopyrite?, pyrite? 

Gangue minerals: Quartz? 

Geologic description:

 The entire island has been mapped as a color anomaly (Cox and others, 1981). A mineralization system on the island has been classified by Wilson (1980) as a volcanic porphyry deposit, although no mention is made of ore or gangue minerals present. Rocks 

consist of andesite flows and sills of Oligocene to Pliocene age and sedimentary rocks of 

the Paleocene and Eocene Tolstoi Formation (Detterman and others, 1981). A hornblende 

andesite sill has been dated at approximately 36 m.y. and sericitic alteration at approximately 30 m.y. (Wilson, 1980). 

Alteration:

 A small zone of sericitic alteration in undescribed rocks lies near the northern part of 

the island (Wilson, 1980). Propylitic and argillic types may also be present. 

Age of mineralization:

Tertiary. 

Deposit model:

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

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

SW007 
Alaska Resource Data File 

Page 15 

17 

Production Status: None 

Site Status: Inactive 

Workings/exploration:

 

Production notes:

 

Reserves:

 

Additional comments:

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

References:

Wilson, 1980; Cox and others, 1981; Detterman and others, 1981. 

Primary reference: Wilson, 1980 

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

Last report date: 1/31/00 

SW007 
Alaska Resource Data File 

Page 16 

Site name(s): Unnamed (near headwaters of Main Creek) 

Site type: Occurrence 

ARDF no.: SW008 

Latitude: 56.9 Quadrangle: SW D-5 

Longitude: 157.5 

Location description and accuracy:

 This site is located near the headwaters of Main Creek in T. 37 S., R. 51 or 52 W., of 

the Seward Meridian (MacKevett and Holloway, 1977, locality 4). Site location is accurate to within 4 miles. 

Commodities: 

 Main: Cu? 

 Other: 

Ore minerals: Quartz? 

Gangue minerals: 

Geologic description:

 At this site hydrothermal alteration is associated with a Tertiary subvolcanic pluton and 

Tertiary volcanic rocks (MacKevett and Holloway, 1977). No mention is made of ore or 

gangue minerals present). 

Alteration:

 Hydrothermal alteration of unknown type. 

Age of mineralization:

 

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 

SW008 
Alaska Resource Data File 

Page 17 

Workings/exploration:

 

Production notes:

 

Reserves:

 

Additional comments:

 This occurrence is located on land selected by the Koniag Native Corporation. 

References:

MacKevett and Holloway, 1977; Detterman and others, 1981. 

Primary reference: MacKevett and Holloway, 1977 

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

Last report date: 1/31/00 

SW008 
Alaska Resource Data File 

Page 18 

 References 

Alaska Division of Natural Resources, 1997, State of Alaska General Land Status with Mineral Resources and 

Mining Claims, Alaska Peninsula, 1 map sheet, scale 1:1,000,000. 

Cox, D.P., Detra, D.E., and Detterman, R.L., 1981, Mineral resource maps of the Chignik and Sutwik Island 

quadrangles, Alaska: U.S. Geological Survey Map MF- 1053K, 2 map sheets, scale 1:250,000. 

Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p. 

Detterman, R.L., Miller, T.P., Yount, M.E., and Wilson, F.H., 1981, Geologic map of the Chignik and Sutwik 

Island quadrangles: U.S. Geological Survey Map I-1229, 1 map sheet, scale 1:250,000. 

Hedderly-Smith, 1977, 1977 Annual report, Alaska search, Koniag Inc. region: Bear Creek Mining Company, 

Spokane Office, 23 p. (held by Kennecott Alaska, Anchorage). 

MacKevett, E.M., and Holloway, C.D., 1977, Table describing metalliferous mineral deposits in the western part 

of southern Alaska: U.S. Geological Survey Open-File Report 77-0169F, 38 p., 1 map sheet, scale 

1:1,000,000. 

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

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

U.S. Bureau of Mines, 1973, Quadrangle map overlays showing mineral deposit locations in Alaska: U.S. Bureau 

of Mines Open-File Report 20-73, 95 map sheets, scale 1:250,000. 

Wilson, F.H.,1980, Late Mesozoic and Cenozoic tectonics and age of porphyry copper prospects, Chignik and 

Sutwik Island quadrangles, Alaska Peninsula: U.S. Geological Survey Open-File Report 80-543, 94 p., 4 

map sheets, scales 1:250,000 and 1000 feet to the inch. 

Young, L.E., St. George, P., and Bouley, B., 1997, Porphyry copper deposits in relation to the magmatic history 

and palinspastic restoration of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of 

Alaska: Economic Geology Monograph 9, 482 p. 

Yount, M.E., Cooley, E.F., and O’Leary, R.M., 1978, Sample location map, analytical data, and statistical summary of analyses of rock samples, Chignik and Sutwik Island quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-0557, 1 map sheet, scale 1:250,000. 

References