Publication Citation

USGS Series Bulletin
Report Number 1122-A
Title Geology of the Spruce Pine District, Avery, Mitchell, and Yancy Counties, North Carolina
Edition -
Language ENGLISH
Author(s) Brobst, Donald Albert
Year 1962
Originating office Geological Survey (U.S.)
USGS Library Call Number (200) E no.1122-A
Physical description Report: iv, pages A1-A26; 2 Plates - Plate 1: 52 x 30 inches, Plate 2: 52 x 27 inches
ISBN 0607643226
Northernmost latitude 0360441
Southernmost latitude 0354919
Easternmost longitude -0815617
Westernmost longitude -0821731

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Abstract

The Spruce Pine pegmatite district, a northeastward-trending belt 25 miles long and 10 miles wide, lies in parts of Avery, Mitchell, and Yancey Counties in the Blue Ridge Province of western North Carolina. The most abundant rocks in the district are interlayered mica and amphibole gneisses and schists, all of which are believed to be of Precambrian age. These rocks are cut by small bodies of dunite and associated rocks of Precambrian (?) age, large bodies of alaskite and associated pegmatite of early Paleozoic age, and basaltic and diabasic dikes and sills of Triassic (?) age. The rocks of the district have been weathered to saprolite that is locally 50 feet thick. The major structure in the area is a southwestward-plunging asymmetrical synclinorium that has its steeper limb on the northwest side. Feldspar, muscovite as sheet and scrap (ground) mica, and kaolin from the alaskite and associated pegmatite account for over 90 percent of the total mineral production of the district. Amounts of other pegmatite minerals, including quartz, beryl, columbite-tantalite, rare-earth and uranium minerals are an extremely small part of the mineral resources. Actual or potential products from other rocks are olivine, vermiculite, asbestos, talc, chromium and nickel, soapstone, mica schist, garnet, kyanite, dolomite marble, and construction materials.