It's not accurate to say there are only 3 mineral groups. There are actually many ways to classify minerals, with hundreds of recognized mineral species. However, some common classifications include:

1. Chemical Composition: This is the most common way to group minerals. Examples include:

* Silicates: Minerals containing silicon and oxygen, often with other elements. Examples: Quartz, feldspar, mica

* Carbonates: Minerals containing carbon and oxygen. Examples: Calcite, dolomite, magnesite

* Oxides: Minerals containing oxygen and a metal. Examples: Hematite, magnetite, corundum

* Sulfides: Minerals containing sulfur and a metal. Examples: Pyrite, galena, chalcopyrite

* Sulfates: Minerals containing sulfur, oxygen, and a metal. Examples: Gypsum, anhydrite, barite

* Halides: Minerals containing a halogen (fluorine, chlorine, bromine, iodine) and a metal. Examples: Halite (rock salt), fluorite, sylvite

2. Crystal Structure: This classification focuses on the arrangement of atoms within the mineral. Examples:

* Isometric: Minerals with cubic symmetry. Examples: Halite, pyrite

* Tetragonal: Minerals with square symmetry. Examples: Zircon, cassiterite

* Hexagonal: Minerals with six-sided symmetry. Examples: Quartz, beryl

* Orthorhombic: Minerals with rectangular symmetry. Examples: Topaz, olivine

* Monoclinic: Minerals with one oblique angle. Examples: Gypsum, orthoclase

* Triclinic: Minerals with no right angles. Examples: Albite, turquoise

3. Physical Properties: This classification uses observable properties like hardness, color, streak, cleavage, and luster. While not a formal grouping like chemical composition, it's useful for identification.

It's important to remember that these classifications are not mutually exclusive. A mineral can belong to multiple groups based on its chemical composition, crystal structure, and physical properties.