(Triclinic).
In the anorthic (from [Greek: an], privative, and [Greek: orthos],
right) or triclinic system none of the three crystallographic axes are
at right angles, and they are all of unequal lengths. In addition to
the parameters a : b : c, it is necessary to know the angles, [alpha],
[beta], and [gamma], between the axes. In anorthite, for example,
these elements are a : b : c = 0.6347 : 1 : 0.5501; [alpha] = 93 deg.
13', [beta] = 115 deg. 55', [gamma] = 91 deg. 12'.