hemihedron Cryst.
(hɛmɪˈhiːdrən, -ˈhɛdrən)
[f. hemi- c + Gr. ἕδρα after hexahedron, etc. Cf. F. hémièdre.]
A form or crystal of a hemihedral type.
| 1837 Dana Min. ii. 19 This species of hemihedral Crystal has been called the inclined hemihedron. 1895 Story-Maskelyne Crystallogr. §137 A form of the hemi-symmetrical kind will be termed a semiform or a hemihedron. Ibid. §176 Holo-systematic haplohedral forms; or holotesseral hemihedra. |
So hemiˈhedrism, hemiˈhedry [cf. F. hémiédrie], the property or quality of crystallization in hemihedral forms.
| 1837 Dana Min. ii. 19 The first species of hemihedrism gives rise to solids, whose opposite planes are not parallel. Ibid., Examples of the first kind of hemihedrism, in which half the angles of the cube are modified. 1864–72 Watts Dict. Chem. II. 143 This kind of hemihedry is strikingly exhibited in apatite. 1883 Nature 1 Feb. 317/1 Some remarks on hemihedry in crystals. |