Iron.—Iron is one of the most widely diffused of metals. It is abundant in the sun; meteorites contain from more than ten to eighty or ninety per cent. of it; all earths and rocks contain at least traces of it; and in various places the deposits of ore in nearly pure form aggregate cubic miles in extent.
In only a few localities is iron ore found in a metallic or "native" form. Many meteorites consist of metallic iron mixed with nickel and manganese, and in Greenland a volcanic dyke or ledge of metallic iron is known to exist. The iron of commerce is derived from "ores," or chemical compounds of iron and oxygen, or iron and carbon. The cheapness of the product depends upon the ease with which the ore may be quarried, transported to coal, and smelted. The following are the ores commonly employed in the production of iron:
Red hematite has a reddish metallic lustre and when pure contains seventy per cent. of iron.[42] It is the most abundant of the workable ores, and certainly the best for the manufacture of Bessemer steel. The ores of the Lake Superior region are mainly red hematite, and the latter constitutes more than four-fifths of the output of the United States.
THE COMPARATIVE PRODUCTION OF IRON AND STEEL
Brown hematite, or limonite, has a chestnut brown color and contains very nearly sixty per cent. of iron[43]; it includes the "bog" ores, and is very abundant. Not far from one-quarter of the Appalachian ores are brown hematite; it constitutes about one-eighth of the output of the United States.
Magnetic iron ore, or magnetite, of which loadstone, a natural magnet, is an example, has a metallic, steel lustre and contains 72.4 per cent. of iron.[44] Most of the ores obtained in Pennsylvania and New York are magnetite. The magnetites furnish about one-sixteenth of the output of the United States.
Carbonate of Iron, or siderite, occurs in a few localities, the ore produced in Ohio being almost wholly of this kind. It contains when pure about forty-eight per cent. of iron.[45] It constitutes less than one per cent. of the output of the United States.
Iron pyrites, or sulphide of iron, sometimes called "fools' gold," is a very common mineral. It is used in the manufacture of sulphuric acid, but is worthless for the production of iron; indeed, the presence of a very small percentage of sulphur in iron renders the latter worthless for many purposes.
Extensive deposits of iron are known to exist in very nearly every country in the world, but those which can be advantageously worked are few in number. In order to be available, the deposits must be within easy transporting distance of the people who use it, and likewise within a short distance of the coal used to manufacture it.