Antigorite is monoclinic in the space group Pm.[13] Although the magensian serpentines have similar compositions, they have significantly different crystallographic structures, which are dependent on how the SiO4 tetrahedra sheets fit in with the octahedral sheets.[14] Antigorite's basic composition has a smaller ratio of octahedral to tetrahedral cations (relative to lizardite and chrysotile),[15] allowing the structure to compensate for the misfit of sheets through periodic flipping of the curved tetrahedra layers, and subsequently their polarity.[16] Polysomes of antigorite are defined by the number of individual tetrahedra (denoted as the value m) which span a wavelength of the direction of curvature.[17] The sheets of tetrahedra allow the platy, fibrous crystals to separate parallel to the 001 (basal) plane, giving antigorite its perfect cleavage.