“ A metalliferous rock is spoken of as an ore when it contains metallic minerals (or in some cases non-metallic minerals, such as sulphur) in such quantities and mixtures as to make possible their profitable extraction. The metal contained in an ore is sometime found in its elemental form, as in the case of gold or platinum, but more frequently as a sulphur compound, or as an oxide carbonate or silicate. Often several different forms of one metallic element are found in the same deposit and several metals are often found together. ”

“ It is believed that ground water, frequently hot, and sometimes under high pressure because of its depth and in vapor form carried many of the metallic elements in solution until a decrease in temperature or pressure caused the precipitation of the metallic salts they had been carrying in solution. ”