74.—Tourmaline.
Occurs in crystals, usually in long, slender three-sided prisms which break easily, glassy lustre; brittle; becomes milk-white by heat; scratches rock-crystal and garnet; gravity 3.
Value.—Used for jewelry.
Localities.—Found in granite rocks. Paris, Albany and Hebron, Me.; Chesterfield and Goshen, Mass.; Newlin and Marple, Pa.