Tags: Chemical Substance, Mineral.
The mineral cristobalite is a high-temperature polymorph of silica meaning that it has the same chemical formula SiO2 but a distinct crystal structure. Both quartz and cristobalite are polymorphs with all the members of the quartz group which also include coesite tridymite and stishovite. Cristobalite occurs as white octahedra or spherulites in acidic volcanic rocks and in converted diatomaceous deposits in the Monterey Formation of the US state of California and similar areas.
