Introduction to crystals
The rhombohedral form of the hexagonal system is difficult to visualize; Steven Dutch's U. Wisconson page does an excellent job. monoclinic. a ≠ b ≠ c α = γ = 90°, β > 90° Two 90° angles, one >90°, with all sides of different lengths. A C cell (also seen in the orthorhombic class) has additional points in the center of each end ...