VALUE.--The most important ore of silver, containing eighty-seven per cent. LOCALITIES.--May be found almost everywhere, except in the coal regions; associated with other ores, quartz, limestone, baryta, etc. Most abundant where mineral veins cross one another. Comstock Lode, Gold Hill, Reese River, Cortez District and Silver-Sprout Vein, Nev.; Clear Creek County, Nev. 64.--SMALTINE. Occurs in crystals and masses; metallic lustre; color tin-white to steel-gray; powder dark gray; brittle; gives off garlic odor in a candle; melted with borax makes a deep blue glass; gravity 6.5 to 7. VALUE.--An ore of cobalt and arsenic, containing eighteen to seventy per cent. LOCALITIES.--Found in veins in granite regions with other ores, Mine la Motte, Mo.; Chatham, Conn. 65.--SMITHSONITE. Occurs in masses, often rounded, covered with minute crystals, or honeycombed; color white, dirty yellow or stone color; glassy lustre; brittle; effervesces in nitric acid; barely scratches glass; barely translucent; gravity 4.4. VALUE.--Yields fifty per cent. of zinc. LOCALITIES.--Found generally in limestone with _galena_ and _blende_. Friedenville, Lancaster and Perkiomen, Pa.; Linden and Mineral Points, Wis.; Lawrence, County, Ark.; Ewing’s Diggings, Minn. 66.--SPATHIC IRON. Occurs in crystals or plates somewhat curving; also (in coal regions) in nodules with concentric layers like an onion; brittle; color varies from white to yellowish-brown or dark-brown; strongly heated it blackens and will then attract the compass needle; the powder effervesces in nitric acid; melted with borax makes a green or yellow glass; gravity 3.8. VALUE.--Yields thirty per cent. of iron, well adapted for steel. LOCALITIES.--Found in granite and coal-formations, often with other ores. Plymouth, Vt.; Sterling, Mass.; Roxbury, Conn.; Antwerp, Herman and Rossie, N. Y.; Fentress and Harlem Mines, N. C.; Coal Regions of Western Pa., Virginia, Eastern Ohio, etc. 67.--SPECULAR IRON ORE. Occurs crystallized and in large masses, high metallic lustre; color steel-gray or iron-black; brittle; opaque except when very thin; the powder when very fine and rubbed on white paper shows red; the powder dissolves slowly in muriatic acid; by a strong heat yields a black mass which attracts the needle; gravity 5. VALUE.--Yields from fifty to seventy per cent. of iron. LOCALITIES.--Found in granite regions. Marquette, Mich.; Pilot Knob and Iron Mountains, Mo.; St. Lawrence County, N. Y.; Bartlett, Lisbon and Franconia, N. H.; Chittenden and Weathersfield, Vt.; Sauk County, Wis. 68.--SPINEL RUBY. Occurs in pyramidal crystals; glassy lustre; powder white; scratches _rock-crystal_; by heat becomes black; gravity 3.5. VALUE.--A gem; clear specimens weighing over four carats, are valued at half the price of the _diamond_. LOCALITIES.--Found in granular limestone and clay. Amity and Gouverneur, N. Y.; Franklin and Byram, N. J.; Bolton and Boxborough, Mass. 69.--STEATITE.