Those marked with an asterisk (*) are minerals,—that is, occur naturally; those with a double asterisk (**), abundantly. The others form the chemical constituents of minerals, but are not minerals themselves.

Carbonic and the Sulphuric acids also occur naturally in volcanic regions, in the form of gases. Lime, Magnesia, and Baryta are also called Alcaline Earths.

XIV. Of the elementary bodies it therefore appears that only two —carbon and sulphur—are found as minerals in any considerable quantity. In composition they are unimportant in rocks, except in the binary compounds given.