Occurs in masses, consisting of minute pearly scales or grains; can be marked by the nail; hardens by heat; soapy feel; gravity 2.5. VALUE.--Used for fire-stones, tubes, in manufacture of porcelain, etc. LOCALITIES.--Found in beds with limestone, serpentine and slate. Orr’s Island, Me.; Francestown, Keene, Orford and Pelham, N. H.; Athens, Cavendish, Marlboro, Moreton, New Fane, Bradboro, Troy, Waterville, Westfield, Weathersfield and Windham, Vt.; Middlefield, Lenox and Westfield, Mass.; Manayunk and Chestnut Hill, Pa.; Albemarle and Loudon Counties, Va.; Staten Island and St. Lawrence County, N. Y.; Bare Hills, Md. 70.--STRONTIANITE. Occurs in crystals and in fibrous or granular masses; glassy lustre; brittle; thin pieces melt before a blow-pipe tinging the flame red; effervesces with acids; gravity 3.6. VALUE.--A source of nitrate of strontia used in fire-works. LOCALITIES.--Found in limestone. Schoharie, Muscalonge Lake, Chaumont Bay and Theresa, N. Y. 71.--SULPHUR. Occurs in crystals, masses and crusts; brittle; can be easily cut; burns with a blue flame and sulphur odor; gravity 2. LOCALITIES.--Found in limestone and gypsum, and around geysers and sulphur springs. Springport, N. Y.; on the Potomac, twenty-five miles above Washington; Put-in-Bay Island, Lake Erie; Clear Lake, Cal.; Santa Barbara County, Col.; Humboldt County, Nev. 72.--TIN ORE. Occurs in crystals, grains and masses; high lustre; powder gray or brownish; brittle; will strike fire with steel; unaltered by heat or acids; gravity 7,--being nearly as heavy as lead-ore. VALUE.--The only ore of tin, containing seventy-nine per cent. No gold-mine ever paid such profits as the tin mines of Cornwall. LOCALITIES.--Jackson, N. H.; Temescal, Cal.; Boonville, Idaho; near Fredericktown, Mo. 73.--TOPAZ. Occurs in crystals; glassy lustre; brittle; scratches _rock-crystal_; not acted upon by ordinary heat or acids; gravity 3.5. VALUE.--A gem; the most esteemed are the rose-red and white. LOCALITIES.--Found in granite. Trumbull, Willimantic and Middletown, Conn.; Crowder’s Mountain, N. C.; Thomas’s Mountains, Utah. 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. 75.--VARIEGATED COPPER ORE. Occurs in crystals and masses; metallic lustre; quickly tarnishes; color between copper-red and light-brown; powder pale grayish-black; dissolves in nitric acid; at a high heat melts to a copper globule; heated on charcoal gives off fumes of sulphur; gravity 5. VALUE.--An important ore of copper yielding sixty per cent. LOCALITIES.--Found in granite, freestone, etc., with other ores. Bristol and Cheshire, Conn.; Mahoopeny, Pa.; Copper Mines of N. J. 76.--WAD.