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CHAPTER VI.
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BERYL GEMS AND SPODUMENE (HIDDENITE).
BERYL (EMERALD, AQUAMARINE, GOLDEN BERYL).
This gem, chemically a silicate of alumina and glucina (or beryllia) and ranking among the most valuable of precious stones, is found quite extensively in North Carolina. Its commoner variety, beryl, occurs at many places in the State, and sometimes of beautiful gem quality; these are the aquamarines, blue to light green and the yellow or golden beryl. We will first treat of the precious variety, emerald.
Emerald Beryl.—Very few genuine emeralds have been found in the United States; and a number of reported specimens, assumed to be such, have proved upon examination to be only deep green beryls. The true emerald owes its color to a minute amount of oxide of chromium. Some beryls are of a very rich light green, and closely resemble emerald, so that they may easily be regarded as such; but they lack the depth of color so valued in the real emerald (see Pls. III and IX). The chief localities are Alexander and Mitchell counties, N. C, where emeralds, or beryls suggesting them occur. In the former it has been found at several different points, with quartz, rutile (some of the finest known), dolomite, muscovite, garnet, apatite, pyrite, etc., all in fine crystals. One of these places, Stony Point, is about 35 miles southeast of the Blue Eidge, and 16 miles northeast of Statesville, N. C. The surface of the country is rolling, the altitude being about 1000 feet above sea level. The soil, which is not very productive, is generally a red, gravelly clay, resulting from the decomposition of the gneissoid rock, and under these circumstances it is easy to find the sources of minerals discovered on the surface. Prof. Washington C. Kerr's theory of the "frost-drift" is well illustrated by the conditions that prevail throughout this region. The unaltered rock appears at Stony Point at a depth of 26 feet and is unusually hard, especially the walls of the gem-bearing pockets.
An exceptionally clear and reliable account of the search for minerals in Alexander County which resulted in the final uncovering of the important emerald and beryl deposits of Stony Point, has been given by the
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