C.L. Sainsbury 1955 <p>A pegmatite deposit about 600 feet in diameter crops on a high bluff less than one-half mile east of a small unnamed cove between Redfish and Byron Bays, on the west coast of Baranof Island, southeastern Alaska.</p><p>The deposit which comprises several pegmatite bodies consists of quartz, albite-oligoclase, microcline and mica, listed in the order of their relative abundance. Feldspar and quartz crystals locally attain a length of more than 1 foot. Some muscovite mica up to 2 inches in diameter occurs, but the major part of the mica is contained in concentrations, containing mica flakes one-half inch across, that often are as large as 10 feet across. Ruby mica of strategic grade has been obtained from float from this deposit.</p><p>None of the rarer minerals such as beryl, columbite-tantalite or cassiterite that often occur in pegmatites were observed in the preliminary examination; and small-size concentrate samples obtained by panning stream sands from the area did not contain recognizable amounts of these rarer minerals. One sample contained a few grains identified as cassiterite. No radioactive anomalies were detected in the pegmatites, or in the stream concentrates.</p><p>The large tonnage of material available arid the favorable location by a good anchorage on an ocean route are favorable factors that should contribute to the development of the deposits. Other deposits of comparable size probably occur in the area.</p> application/pdf 10.3133/ofr55159 en U.S. Geological Survey Geology of two areas of pegmatite deposits in southeastern Alaska reports