Having six sides and six angles; six-sided.
It is for any of the mineral that has four axes out of which three are equal in length and lie at an angle of 120° from each other. The fourth one may be long or short but at right angle toward the other corners.
A crystal system characterised by the presence of a hexad (axis of 6-fold rotation). Two of the axes are 120deg apart and are of equal length. The third axis (c) is aligned with the hexad, and is 90deg to the other two axes.