| 释义 |
ditrigonal, a. Cryst.|daɪˈtrɪgənəl|
[f. di-2 + trigonal.]
Having six (dihedral) angles, of which the first, third, and fifth are equal, and also the second, fourth, and sixth, but those of the one set not equal to those of the other. (Cf. dihexagonal, ditetragonal.)
1878Gurney Crystallogr. 60 Some minerals..appear to possess a truly hexagonal and not merely a trigonal or ditrigonal symmetry. 1895Story-Maskelyne Crystallogr. v. §116. 133 A form with six poles grouped round the axis, that may be viewed as an axis of ditrigonal symmetry. Ibid. vii. §244. 293 The ditrigonal scalenohedron.
Hence diˈtrigonally adv.
1895Story-Maskelyne Crystallogr. vii. §246. 296 The summit-quoins are symmetrical ditrigonally on the axis. |