OCCURRENCE AND CHEMICAL COMPOSITION OF ZIRCONOLITE (CaZrTi_2O_n)

摘要

Zirconolite, ideally CaZrTi_2O_7, is a rare accessory mineral crystallising under different geological conditions and in a wide range of generally SiO_2-poor rock types. It has been observed in: kimberlite; ultrabasic rocks, including metasomatized mantle rocks; anorthosite; dolerite; gabbroic rocks; dioritic rocks (diorite-monzodiorite-granodiorite); syenite and nepheline syenite; sanidinite; carbonatite; metasomatic and metamorphic rocks; and placer deposits. It also occurs in lunar samples, where it has been found in basalts, feldspathic peridotite, lithic fragments, granite, and metamorphosed breccia. Moreover, zirconolite has been reported as a phase in plagioclase-olivine inclusions in the Allende carbonaceous chondrite.