Metallurgy in a general sense, comprehends the art of working metals from the state of ore to the utensil; and in this sense, assaying, smelting, refining, smithery, etc, are branches of metallurgy. In a more limited sense, however, it includes only the separation of metals from their ores, or other combinations. Few metals are found in a pure state; gold, silver, and copper are sometimes exceptions; the other metals are generally found in the state of ores, in which they are mixed and blended with other substances, so as not to have the ductility, lustre, or other qualities of metals. Sometimes the ore is only a pure oxide, and requires but the abstraction of the oxygen, by fusion with inflammable substances. The ores of metals are always separated from the rocks on each side by a quantity of spar, quartz, or sometimes softer clay or earth, called the matrix or rider. The first operation in metallurgy is to separate the ore from the matrix; but when the ore is found in large masses, most of it can be obtained by the miner's implements free from the matrices, and those portions that adhere are knocked off by hammers.

In other cases, when the ore is intimately mixed with the matrix, it becomes necessary to resort to different processes, such as roasting, pounding, and washing; the latter operation effecting the separation by the difference of specific gravity of the mixed matters; the earthy parts being floated away, leaving the metallic portion behind. See the following article.