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How are minerals classified by their dominant anions or anionic groups?

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Two diagrams show the three-dimensional structure of a methane molecule: panel A uses a ball-and-stick model with a central carbon atom connected to four hydrogen atoms in a tetrahedral arrangement, while panel B illustrates the bond angle of 109.5 degrees and bond length of 1.09 angstroms between carbon and hydrogen atoms. — chemical compound Methane, in which four hydrogen atoms are bound to a single carbon atom, is an example of a basic chemical compound. The structures of chemical compounds are influenced by complex factors, such as bond angles and bond length.

Minerals are classified at the highest level based on their dominant anion or anionic group. This method is used because minerals sharing the same anionic group exhibit more pronounced similarities in their properties than those sharing the same dominant cation, and they are frequently found in similar geologic environments.1

The primary classes based on this chemical composition include:

Native elements
Sulfides
Sulfosalts
Oxides and hydroxides
Halides
Carbonates
Nitrates
Borates
Sulfates
Phosphates
Silicates1

While chemical composition provides a foundation for classification, modern mineralogy also incorporates internal crystal structure—determined via X rays—to provide a more complete understanding of a mineral's nature and physical properties. For example, the silicate group is further subdivided based on the topology of its SiO₄ tetrahedrons.1