Changes

Four [[Axis|axes]] of [[symmetry]]: three, of equal length, lie in a plane at 120°; the fourth axis is longer or shorter and is at [[right angle]]s to the others.

Four [[Axis|axes]] of [[symmetry]]: three, of equal length, lie in a plane at 120°; the fourth axis is longer or shorter and is at [[right angle]]s to the others.

[[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 [[triangle|triangular]] or [[hexagon]]al 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

==Sources==

==Sources==