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.

[Illustration: 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.

For these reasons most of the workable deposits of ore are in or near
the great centres of population in western Europe and the eastern part
of the United States; as a matter of fact, practically all the iron and
steel of the latter country is produced in the populous centres of the
Atlantic slopes. In most great steel-making districts it is essential to
mix the native ores with special ores brought from a distance, the
latter being used to give strength and hardness to the resulting metal.
Ores from Sweden, and from Juragua, Cuba, are employed for this purpose
i