[[Crystals]] are generally [[prismatic]] or [[columnar]], with a rounded [[triangular]] or [[hexagonal]] cross section; characteristic forms are three- or six-sided [[prism]]s, [[pyramid]]s, and [[rhombohedron]]s. The very similar ''[[trigonal system]]'' is often included within the hexagonal system. Chesterman, pp. 33-34 | [[Crystals]] are generally [[prismatic]] or [[columnar]], with a rounded [[triangular]] or [[hexagonal]] cross section; characteristic forms are three- or six-sided [[prism]]s, [[pyramid]]s, and [[rhombohedron]]s. The very similar ''[[trigonal system]]'' is often included within the hexagonal system. Chesterman, pp. 33-34 |