Six Crystal System of Minerals
Crystals can be classified into 6 crystal systems according to their relative lengths and angles of crystal axes. They are isometric, hexagonal, tetragonal, orthorhombic, monoclinic and triclinic.
| System | Criterion | IIIustrations | Examples |
|---|---|---|---|
| Isometric | a1=a2=a3 α=β=γ=90。 |
 |
Diamond, Fluorite, Halite |
| Tetragonal | a1=a2≠c α=β=γ=90。 |
 |
Scheelite, Zircon |
| Orthorhombic | a≠b≠c α=β=γ=90。 |
 |
Hemimorphite, Native Sulfur, Topaz |
| Hexagonal | a1=a2=a3 a1∧a2=a2∧a3 =a1∧a3=120。 a1∧c=a2∧c =a3∧c=90。 |
 |
Quartz, Calcite, Graphite |
| Monoclinic | a≠b≠c α=γ=90。, β≠90。 |
 |
Gypsum, Orthoclase, Augite |
| Triclinic | a≠b≠c α≠β≠γ≠90。 |
 |
Plagioclase, Kyanite |
Halite, Isometric
California, USA
Gypsum, Monoclinic
Brazil
Albite & Microcline, Triclinic
Brazil
Scheelite, Tetragonal
Chungju, Korea
Hemimorphite, Orthorhombic
China
