Most of this diversity, however, is due to the diversity of the Non-metals Subclass . The Metals Subclass and related metal alloys contains metals whose properties are rather similar due to the common way in which they crystallize and bond. The greatest difference in the metals is color. The non-metals, however, are extremely diverse. For instance, the hardest mineral known to man is from this subclass, as well as one of the softest.
Metal alloys are minerals that are composed of combinations of different metals in one mineral.
All native metals are impure usually by several percentage points, but these are not distinguished as distinct minerals unless they meet certain mineralogical criteria. Generally they must be consistent in their composition and have their respective elements occupy specific sites in their crystal lattice in order to be named as new minerals. Alloys that are composed of semi-metals with metals are classified as sulfides but are sometimes listed as elements. They usually share similarities to other sulfides in their physical properties. These minerals are in the Selenides , the Tellurides , the Antimonides and the Arsenides Subclasses of the Sulfide Class.