Red Hematite
A very important class of iron ores, which vary in color from a deep-bright red to gray. Its steak and powder are a blood-red. Specular iron is a variety of hematite often found in beautifully colored crystals. Clay ironstone consists of hematite mixed with certain proportions of clay and other impurities. The common red chalk is a variety of hematite mixed with clay. It is a valuable iron ore, and yields when pure about 70 per cent of metallic iron. Its powder is used as a coloring material for paints and for polishing metals. The variety called "puddler's-mine," being of a soft, compact nature, is used for making and repairing the bottoms of puddling-furnaces; when used for this purpose it is called "ore" by the puddlers. See ORES; PUDDLING-FURNACE.