Crystal Systems
Crystal systems are defined by the lengths of their axes (a, b, c) and the angles between them (α, β, γ).
1. Cubic (Isometric):
* a = b = c
* α = β = γ = 90°
* Examples: Halite (rock salt), Diamond, Garnet
2. Tetragonal:
* a = b ≠ c
* α = β = γ = 90°
* Examples: Zircon, Rutile, Cassiterite
3. Orthorhombic:
* a ≠ b ≠ c
* α = β = γ = 90°
* Examples: Topaz, Olivine, Sulfur
4. Hexagonal:
* a = b ≠ c
* α = β = 90°, γ = 120°
* Examples: Quartz, Beryl, Apatite
5. Trigonal (Rhombohedral):
* a = b = c
* α = β = γ ≠ 90°
* Examples: Calcite, Tourmaline, Dolomite
6. Monoclinic:
* a ≠ b ≠ c
* α = γ = 90°, β ≠ 90°
* Examples: Gypsum, Orthoclase, Pyroxene
7. Triclinic:
* a ≠ b ≠ c
* α ≠ β ≠ γ ≠ 90°
* Examples: Turquoise, Kyanite, Microcline
Key Points
* Symmetry: The crystal systems are based on the inherent symmetry present within the crystal structure. This symmetry is reflected in the arrangement of atoms, ions, or molecules in the crystal.
* Unit Cell: Each crystal system is defined by a specific unit cell – the smallest repeating unit that makes up the crystal lattice.
* Physical Properties: Crystal systems influence a mineral's physical properties, such as cleavage, hardness, and optical properties.
Let me know if you would like to delve deeper into a specific crystal system or any related aspects of crystallography!
