| 释义 |
hemitrope, a. and n. Cryst.|ˈhɛmɪtrəʊp|
[ad. F. hémitrope (1801 Haüy), f. hemi- + Gr. -τροπος turning.]
A. adj. = hemitropic.
1805–17R. Jameson Char. Min. (ed. 3) 225 Hemitrope..that is, one-half turned round, when it is composed of two halves of one and the same crystal, of which the one-half appears to be turned upon the other one-half of the circumference. Example, Twin-crystal of felspar. 1823H. J. Brooke Introd. Crystallogr. 89 A hemitrope crystal..resembling one of the varieties of the common spinelle. 1895Story-Maskelyne Crystallogr. §159 In the hemitrope position..one pair of the faces forms a re-entrant angle.
B. n. A hemitropic crystal.
1805–17R. Jameson Char. Min. (ed. 3) 176 Haüy has given to these reversed crystals the name hemi-tropes, denoting one half reversed. 1895Story-Maskelyne Crystallogr. §157 Repetition of the twinning on similar twin-faces may indeed occur..Such crystals are triple, quadruple, &c. hemitropes (or triplings, fourlings, &c.).
So ˈhemitropism, heˈmitropy, hemitropic crystallization.
1845Encycl. Metrop. IV. 578 A variety of cases of hemitropism. 1879Rutley Study Rocks x. 92 Due to hemitropy or a half revolution of one of the halves of the crystal. 1895Story-Maskelyne Crystallogr. §163 It results from the law of hemitropy that each pair of corresponding faces on the two crystals lies in one zone with the twin-plane and that the faces make equal angles with it. |