Gems & Precious Stones: Corundum, Sapphire, Ruby, Oriental Topaz, Oriental Emerald, Diaspore & Spinel Page 48



	40 GEMS AND PRECIOUS STONES IN THE Corundum is a mineral of great importance, though not of frequent occurrence; in combination, however, especially with silica, alumina enters into a vast number of mineral species and varieties. Its great hardness gives it value as a polishing material, and as such it has no substitute. It is found in the United States, chiefly in the crystalline rocks along the Appalachian Mountains, from Chester, Mass., to northern Georgia, and also in Montana. At Chester, where the deposits have long been known and worked, the mineral consists chiefly of emery, which is corundum mixed with magnetite, and somewhat softer than corundum alone. No gems have been found here. At Pelham, Mass., corundum in small quantities has been recognized, and Prof. Charles U. Shepard ¹ found asteriated crystals in nodules of cyanite at Litchfield, Conn., also at Norwich, Conn., where he found small blue crystals enclosed in fibrolite. It is likewise found in the metamorphic rocks of the Highlands of New York and northern New Jersey. At Vernon, N. J., forty years ago, crystals of sapphire and ruby corundum were found, but always opaque, so that, while many specimens were obtained from this locality, some of which have been cut, it is probable that none of them has furnished a transparent gem. It is of interest to know that rubies from Mandalay, Burmah, occur in similar association with limestone; hence they are generally found detached and separated from their original matrix. Some handsome cabinet specimens, showing asterism, have been obtained from Delaware, Chester, and Lancaster Counties, Pa.; few, however, were suitable for cutting. Crystals have been found in Virginia, in Louisa County, and near Staunton, Augusta County. The great corundum region is in the crystalline rocks of North Carolina, where in Madison, Buncombe, Haywood, Jackson, Macon, and Clay Counties, numerous localities are known. A second and a third line of localities are recognized, but they are of slight importance. According to Thomas M. Chatard,²of the United States Geological Survey, the corundum region extends from the Virginia line through the western part of ¹ Report on the Geological Survey of Connecticut, p. 64, New Haven, 1837. •Mineral Resources of the United States, p. 714, 1883-1884.