Mineral Classification by Chemical Composition
Minerals are naturally occurring, inorganic substances with a quantifiable chemical composition and a crystalline structure. The term "mineral" refers to both a material's chemical composition, and its physical structure. For a substance to be classified as a mineral, it must be a solid, non-liquid substance, and a crystal structure. The term "rock" should not be confused with the term "mineral," as rock is an aggregate amalgamation of one or more minerals, and can also contain organic substances.
Substances that are "mineral-like" but don't meet this definition are classified as "mineraloids." Minerals range in composition from pure elements (carbon and metals) or salts, to highly complex silicates (emeralds, tourmaline, etc.). According to the International Mineralogical Association, there are currently over 4,000 known minerals, which are categorized according to their chemical composition or "mineral class." There are eight mineral classes which are categorized by anion (negative ion) group.
The minerals shown on this mineral classification chart are listed in the approximate order of their abundance within the Earth's crust, starting with the most abundant "silicate class" of minerals.
1. Silicate Mineral Class
2. Carbonate Mineral Class
3. Sulfate Class
4. Halide Mineral Class
5. Oxide Mineral Class
6. Sulfide Mineral Class
7. Phosphate Mineral Class
8. Element Class
A "mineraloid" is a mineral-like substance that does not demonstrate crystallinity and who's chemical composition is beyond the accepted ranges for specific minerals. Pearls contain the mineral "calcium carbonate" but the structure is bonded together by organic materials. Obsidian is not a "crystal" but is instead amorphous-glass. Amber is a heterogeneous composite with a "gem-like" appearance, but consists of resinous bodies that are soluble in alcohol.