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30                         METALLURGY   OF   CAST   IRON.
able grade can be obtained without the cost necessary to prepare objectionably high sulphur and phosporus ore for smelting.
Brown hematites include bog ores, which are found in shallow rivers, etc., and are now very little used; they are largely the result of the oxidation of the carbonates of iron. No ore is more irregular in its characteristic qualities. It may be of a yellow as well as a brown color. It is generally porous and easy to reduce and smelt in a blast furnace. It is found mixed in undue proportion with earthy and gangue matter and often rich in carbonate of lime, and is also generally high in phosphorus. It is found in beds and veins and often forms the cover of copper ores.
Carbonate and spathic ores are generally of a whitish color, but they are often found mixed with manganese, which turns them brown. They are largely found in massive veins of great thickness and in combination with other carbonates and may be of a greenish gray color. Brown hematites are also found existing in sands or soils of a coarse character. There is some dispute as to their value. Some claim that they excel red hematites for making high grade iron. A variety of carbonate of iron ores is known as clay iron stone by reason of its being found in the clay bands of the coal fields. This class of ore is largely used in Scotland as well as in England. " Black band " is one variety of this class of ores, and is of a glossy black color.
Black band ores give strong irons, and when mixed with soft hematite ores make a soft, or good grade of Scotch iron; but of late years they have become so scarce that they cannot compete with the more plen-as long as sufficient ore of suit-             {f H \esent in the ore.    Both these manganese metals are               jf|V