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Of the 1,500 known mineral species, perhaps 200 figure in commerce as mineral resources.

For the mineral substances used commercially, the term "mineral" is used in this chapter with a broad significance to cover any or all of the materials from which the needed elements are extracted—whether these materials be single minerals or groups of minerals; whether they be rocks or ores; whether they be liquid or solid.

The following figures are generalizations based on the miscellaneous information available. The purpose is to indicate the general perspective rather than the detail which would be necessary for precise statement.