hexad axis

hexad axis

[′hek·sad ‚ax·səs]
(crystallography)
A rotation axis whose multiplicity is equal to 6.
References in periodicals archive ?
There are two generally accepted locations for the [CO.sub.3.sup.2-] ion in the apatite lattice: one on the hexad axis at the [OH.sup.-] ion site (type-A) and the other for [PO.sub.4.sup.3-] (type-B).