What are the different crystal systems?

There are seven crystal systems that categorize all known crystals based on their atomic structure and symmetry. These systems are:

1. Cubic (Isometric) System:
   • Highest symmetry
   • Three equal axes at right angles
   • Examples: Diamond, salt (halite), garnet, pyrite, fluorite, sphalerite, galena
2. Tetragonal System:
   • Three axes at right angles, two equal, one different
   • Examples: Zircon, rutile, graphite, chalcopyrite, stannite
3. Orthorhombic System:
   • Three unequal axes at right angles
   • Examples: Topaz, sulfur
4. Hexagonal System:
   • Three equal axes in one plane at 120° angles, fourth axis perpendicular
   • Examples: Beryl, apatite, vanadinite, nepheline, cancrinite, benitoite
5. Trigonal (Rhombohedral) System:
   • Often considered part of the hexagonal system
   • Three equal axes, equally inclined
   • Examples: Quartz, calcite, tourmaline
6. Monoclinic System:
   • Three unequal axes, two at right angles, third inclined
   • Examples: Gypsum, orthoclase feldspar
7. Triclinic System:
   • Lowest symmetry
   • Three unequal axes, none at right angles
   • Examples:  Plagioclase feldspar, turquoise,  rhodonite, microcline, wollastonite

Each of these systems is defined by its unique combination of symmetry elements, which include rotation axes, mirror planes, and centers of symmetry. The crystal system of a mineral determines many of its physical properties, including cleavage, optical characteristics, and crystal habit.

Visit MineralStory today to discover our collections of Crystals and Minerals!