Crystal System(redirected from Bravais law)
Also found in: Dictionary.
crystal system[¦krist·əl ′sis·təm]
any of the seven groups of crystals obtained when a classification is made according to the symmetry of the unit cell. A system is characterized by the ratios between the a, b, and c axes and by the angles α, β, and γ of the unit cell. The seven systems are cubic (a = b = c; α = β = γ = 90°), tetragonal (a = b ≠ c; α = β = γ = 90°), hexagonal (a = b ≠ c; α = β = 90°; γ = 120°), trigonal (a = b = c; α = β = γ ≠ 90°), orthorhombic (a ≠ b ≠ c; α = β = γ = 90°), mono-clinic (a ≠ b ≠ c; α = β = γ = 90°; β ≠ 90°), and triclinic (a ≠ b ≠ c; α ≠ β ≠ γ ≠ 90°). As the broadest classification of crystal symmetry, each crystal system includes several symmetry point groups and Bravais lattices.