a. Cryst. [f. as prec. + -ID2.] = TETRAHEDRAL a. 2.
1895. Story-Maskelyne, Crystallogr., 208. Tetrahedrid mero-symmetry. The second case of holo-systematic hemi-symmetry, in which every normal is represented by a single face, is that [etc.]. Ibid., 206, 207, 210.
