The native elements are divided into the two distinct sections of the Metals and the Non-metals, and these are connected by the transition class of the Semi-metals. The distinction between them as regards physical characters and chemical relations has already been given.

The only non-metals present among minerals are carbon, sulphur, and selenium; the last, in one of its allotropic forms, is* closely related to the semi-metal tellurium. The native semimetals form a distinct group by themselves, since all crystallize in the rhombohedral class of the hexagonal system with a fundamental angle differing only a few degrees from 90°, as shown in the following list: