Mindat Logo

Windy Bay Occurrence, Alaska Peninsula District, Lake and Peninsula Borough, Alaska, USA

Latitude: 56°8'34"N
Longitude: 158°46'44"W
This site is partially on land selected by the Bristol Bay Native Corporation. The remainder is within the Alaska Peninsula National Wildlife Refuge.
Location: This site is approximately 2 miles west of the head of the north arm of Windy Bay and includes the headwaters of streams draining into that head of the bay (Cox and others, 1981, locality 9). The site is accurate as plotted.
Geology: The geologic setting at this site consists of a quartz diorite stock which has intruded sedimentary units of the Jurassic Naknek Formation (Fields, 1977). These units include grits, graywacke, siliceous siltstone, and black shale. A discontinuous color anomaly is present along the inferred contact zone (Fields, 1977). The sediments near the contact have been hornfelsed and contain pyrrhotite, pyrite, rare chalcopyrite, and magnetite as disseminations and as veinlet and fracture fillings. Total sulfide content is 1-5 percent. Sulfides occur up to 1000 feet from the contact. The sulfide content of the intrusive is 1 percent or less. Chalcopyrite is present on fracture surfaces and in quartz-chlorite and pyrite veinlets. These strike approximately N 25 W and cover an area of 1000 by 4000 feet. Samples of the mineralized intrusive contained up to 424 ppm copper, 0.13 ppm gold, 32 ppm lead, 25 ppm molybdenum, and 9 ppm zinc (Fields, 1977). The intrusive exhibits local chloritization along with scattered patches of epidote and secondary biotite. The hornfelsed sediments have been silicified and contain secondary biotite and minor chlorite.
Workings: Bear Creek Mining Company briefly explored this site during the period 1975-1976. The few samples collected contained up to 424 ppm copper, 0.13 ppm gold, 32 ppm lead, 25 ppm molybdenite, and 9 ppm zinc (Fields, 1977). Resource Associates of Alaska briefly sampled this occurrence in 1979 (Anderson and others, 1979).
Age: Tertiary.
Alteration: Alteration in the intrusive consists of local zones containing chlorite, epidote, and secondary biotite. The sediments near the intrusive contact have been hornfelsed, silicified, and contain chlorite and secondary biotite.

Commodities (Major) - Cu, Mo; (Minor) - Au, Pb, Zn
Development Status: None
Deposit Model: Porphyry copper; porphyry copper-gold; porphyry copper-molybdenum (Cox and Sing


Anderson, G.D., Fitch, G.M., Lappie, D.W., Lindberg, P.A., and Fankhauser, R.E., 1979, Exploration and evaluation of Bristol Bay Native Corporation Lands, Vol. II, Book 1: Prepared for Houston Oil and Minerals Company by Resource Associates of Alaska, 78 p. (Report held by Alaska Earth Sciences, Inc., Anchorage, Alaska.) 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 Miscellaneous Field Studies Map MF- 1053-K, 2 sheets, scale 1:250,000. Fields, E.D., 1977, 1976 Annual report: Alaska search, Chignik area-Bristol Bay region: Bear Creek Mining Company, 44 p., 22 map sheets. (Report held by the Aleut Corporation, Anchorage, Alaska.)

Mineral List

'Chlorite Group'

9 entries listed. 8 valid minerals.

The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.
This page is currently not sponsored. To sponsor this page click here.

Mineral and/or Locality  
Search Google  
Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
Current server date and time: December 20, 2014 07:20:21 Page generated: June 15, 2011 01:46:23
Mineral and Locality Search
and/or Locality:
Fade toolbar when not in focusFix toolbar to bottom of page
Hide Social Media Links
Slideshow frame delay seconds