释义 |
cristobalite Min.|krɪˈstəʊbəlaɪt| Also erron. christobalite, crystobalite. [ad. G. cristobalit (G. vom Rath 1887, in Neues Jahrbuch für Min. I. 198), f. the name of Cerro San Cristóbal, near Pachuca, Mexico, where it was first found: see -ite1.] One of the three main forms of silica (the others being quartz and tridymite), formed at high temperatures as high-cristobalite and changing at lower temperatures to a structurally related metastable polymorph, low-cristobalite, which occurs both massive (e.g. in opal) and as small, usu. octahedral, crystals.
1888Min. Mag. VIII. 36 A New Mineral. Cristobalite... An analysis..gave 91 per cent. of silica and 6 per cent. of oxide of iron and alumina. 1920Brit. Museum Return 144 Artificial minerals (cristobalite, fayalite, rhodonite, apatite, spinel..) from furnace slags. 1935Discovery July 206/1 When ware is fired above a certain temperature a very large number of extremely fine crystals of a mineral (crystobalite) are formed. 1959Chambers's Encycl. IX. 423/1 Both cristobalite (stable 1,470°–1,710° C) and tridymite (stable 870°–1,470° C) are known to occur in certain natural lavas. 1962C. Frondel Dana's Syst. Min. (ed. 7) III. 287 In recent years..study has shown that opal..is a submicrocrystalline aggregate of crystallites of cristobalite. |