Unnamed Occurrence (ARDF - PA035; near Redfish Bay), Chicagof District, Sitka Borough, Alaska, USA
This page is currently not sponsored. Click here to sponsor this page.
Location: This occurrences is a pegmatite about 600 feet in diameter that is about 1.0 mile west of the head of Redfish Bay near the middle of the south boundary of section 36, T. 63 S., R. 67 E. The location is accurate.
Geology: As described by Sainsbury (1957), this occurrence consists of a circular body of pegmatite about 600 feet in diameter. The pegmatite is in a large composite intrusive body near the contact of monzonite or granite and quartz diorite. Loney and others (1975) map the body as tonalite and granodiorite of Tertiary age. Detailed mapping by Sainsbury indicates that the pegmatite consists of two or more dikelike phases. The pegmatite is zoned with a core of quartz surrounded by a shell of variable mineralogy that includes areas of perthite, quartz, and graphic granite; microcline-perthite; and perthite, mica, and quartz. A border zone is generally quartz and graphic granite. The chief commodity of interest is microcline-perthite that occurs in zones 4 to 10 feet thick; the largest zone is at least 120 feet long and 6 to 8 feet thick. There is some optical-grade quartz. Sainsbury tentatively identified a few grains of cassiterite, but there is no indication of beryllium, columbium, or tantalum minerals. The pegmatite is not radioactive.
Workings: Probably none beyond surface examination and sampling by the U.S. Geological Survey and U.S. Bureau of Mines.
Age: The pegmatite is in a large Tertiary granitic intrusion and is probably the same age.
Commodities (Major) - Microcline-perthite, quartz? ; (Minor) - Sn?
Development Status: None
Deposit Model: Pegmatite.
3 entries listed. 1 valid mineral.
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.
Berrryhill, R.V., 1963, Examination of a pegmatite deposits near Redfish Bay, Baranof Island, southeastern Alaska: U.S. Bureau of Mines Examination Report 136, 5 p. Bittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p. Loney, R.A., Brew, D.A., Muffler, L.J. B., and Pomeroy, J.S., 1975, Reconnaissance geology of Chichagof, Baranof, and Kruzof Islands, southeastern Alaska: U.S. Geological Survey Professional Paper 792, 105 p. Sainsbury, C.L., 1957, Some pegmatite deposits in southeastern Alaska: U.S. Geological Survey Bulletin 1024-G, p. 141-161. Skow, M.L., 1962, Mica, a materials survey: U.S. Bureau of Mines Information Circular 8125, 240 p.