- Iron is found chiefly in the earth's crust in combination with oxygen. There are several kinds of ores from which iron is made, but the most important are the various oxides, the carbonates, and the sulphides. From the two former almost all the iron of commerce is obtained. Magnetic ore is the richest of all the ores, and from it are made the finest iron and the best steel. It is found in large masses in Sweden, Norway, Russia, and North America, and in some parts of England. Some specimens of this ore form natural magnets. Magnetic ore when pure contains fully 72 per cent, of metallic iron. Hematite ore in its pure state contains about 70 per cent of iron. This ore is found in great abundance in Chili and other parts of South America, in Algeria, England, Norway, Sweden, and in large beds in Canada, Pennsylvania, Missouri, Michigan, Wisconsin and Wyoming. In addition to the ores mentioned there are many other kinds, such as brown ore, bog ore or. limonite, spathic ore, etc.
Cast-iron, or pig-iron, as it is commonly called, is made by smelting or melting iron ore in a blast furnace. Iron smelting is necessary to free the ore from all foreign ingredients, to reduce the iron oxide to metallic iron, and to allow the reduced iron to combine with such an amount of carbon as to form therewith a fusible compound. Cast iron is used for making gas and water pipes, lampposts, pillars and fronts for buildings, railings and many other things. It contains from 3 to 6 per cent, of carbon, and cannot be hammered, as it is brittle. To make it into wrought iron - that is, softer iron which can be hammered or rolled into plates - the cast iron is melted in another kind of furnace, and stirred up so that the air can get to it. In this way the carbon is burned out, and it contains only 1/2 per cent, of carbon. Wrought iron is easily hammered into bars, rolled into plates, drawn out into wire, or made into steel. Iron plates for steam boilers and ships, anchors, chain cables, ploughs, wheel-tires, horseshoes, shovels and spades, nails and spikes, wire, the iron part of most tools, etc., are made from it. Pieces of wrought iron can be welded or joined into one by hammering them together when red hot. (See Steel.)