PLAGIHEDRAL CRYSTAL
\plˌad͡ʒɪhˈiːdɹə͡l kɹˈɪstə͡l], \plˌadʒɪhˈiːdɹəl kɹˈɪstəl], \p_l_ˌa_dʒ_ɪ_h_ˈiː_d_ɹ_əl k_ɹ_ˈɪ_s_t_əl]\
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[Gr.] As quartz, which commonly takes the form of a six-sided prism terminated by a pyramid. In some cases the solid angles at the junction are replaced by secondary planes obliquely placed ; the form of crystal is then said to be plagihedral, and may be right-handed or left-handed according to the direction of the secondary planes. This difference in the form of the crystals corresponds to a difference in their action on polarized light.
By Henry Percy Smith
Word of the day
hydromorphic
- [Greek] Structurally adapted to an aquatic environment, as organs of water plants.