combining form of Gr. τέταρτος fourth (cf. TETRA-), in scientific terms belonging chiefly to crystallography. Tetartohedral a. [Gr. ἕδρα base], having one fourth of the number of faces required by the highest or holohedral degree of symmetry belonging to its system; hence Tetartohedrally adv., in a tetartohedral manner. Tetartohedric, -hedrical adjs., = tetartohedral. Tetartohedrism, the property or quality of crystallizing in tetartohedral forms; the condition in which a crystal symmetrically develops only one-fourth of the number of planes demanded by holohedral symmetry. Tetartohedron, a tetartohedral crystal. Tetartohedry, = tetartohedrism. Tetartohexagonal a., having one quarter of the number of normals belonging to the hexagonal system. Tetartoprismatic a., Tetartopyramid: see quots. Tetartosymmetric, -symmetrical adjs.: see quot. Tetartosymmetry, a variety of merosymmetry, in which only one-fourth of the faces of the holosymmetrical form are retained. Tetartosystematic a., said of a form in which only one-fourth of the origin-planes are extant.
1858. Dana, Min. (ed. 4), 49. They are *tetartohedral forms, or contain only one-fourth the number of planes occurring under complete symmetry.
1864. Watts, Dict. Chem., II. 144. Quartz likewise exhibits other forms of tetartohedral development.
1888. Rutley, Rock-Forming Min., 64. The development of certain plagihedral, or tetartohedral, faces.
1864. Webster, *Tetartohedrally.
1854. Pereira’s Pol. Light, 234. Doubly oblique prismatic system … or the *tetartohedric-rhombic system.
1860. Mayne, Expos. Lex., *Tetartohedrical.
1858. Dana, Min. (ed. 4), 49. A form of this kind … is found in Titanic Iron, and is called rhombohedral *tetartohedrism.
1895. Story-Maskelyne, Crystallogr., 160. The ambiguity in which the terms hemihedrism, tetartohedrism, etc. are involved. Ibid., 231. There can only be a single kind of *tetartohedron in the Cubic system.
1864. Watts, Dict. Chem., II. 144. *Tetartohedry. Quartz affords a remarkable example of a combination in which only one-fourth of the possible faces are present.
1895. Story-Maskelyne, Crystallogr., 284. Six faces corresponding to three normals: *tetarto-hexagonal diplohedral forms. Three faces corresponding to three normals: tetarto-hexagonal haplohedral forms.
1847. Webster, *Tetartoprismatic,… one fourth prismatic, applied to oblique rhombic prisms.—Mohs.
1851. Richardson’s Geol., v. (1855), 98. Classification of Mohs … V. The Tetarto-Prismatic is composed of the oblique rhomboidal prism.
1891. Cent. Dict., *Tetartopyramid,… a quarter-pyramid: said of the pyramidal planes of the triclinic system, which appear in sets of two (that is, one fourth the number required by a complete pyramid).
1895. Story-Maskelyne, Crystallogr., 159. Mero-symmetrical forms may be hemi-symmetrical … or *tetarto-symmetrical, presenting one-quarter only of the faces of the holo-symmetrical form. Ibid., 160. *Tetarto-symmetry, where the form is (i) hemisystematic and haplohedral, (ii) *tetarto-systematic and diplohedral. Ibid., 308. Tetarto-systematic haplohedral forms.
b. Path. ǁ Tetartophyia [Gr. φυή growth], a remitting quartan fever.
1857. Dunglison, Dict. Med. Sc., Tetartophia,… a quartan, in which the intermission is inordinately short or imperfect.
1895. Funk’s Stand. Dict., Tetartophyia.
