corundum, ruby, sapphire, North Carolina.12, USA.12, gems

A paper by Charles W. Jenks on corundum and its gem varieties, based largely on his personal observations of the corundum deposits of western North Carolina. Jenks discusses the historical use of corundum as an abrasive, compares its cutting power with emery and diamond, and describes contemporary experiments with manufactured corundum grinding wheels. Much of the paper concerns the North Carolina occurrence, where massive corundum and colored crystals were found together in chloritic veins associated with serpentine; he describes the mine workings, gangue minerals, crystal forms and several unusually large specimens. Jenks also discusses the corundum gem varieties then known under such names as “Oriental” sapphire, ruby, asteria, emerald, topaz and amethyst, and compares the American material with that from Ceylon, India and Burma. The paper is valuable as an early firsthand account of corundum mining in the United States and of the developing industrial and gemological uses of the mineral.