A mineral of volcanic rocks that solidified at a higher temperature. Cristobalite is chemically the same as quartz, with the chemical formula SiO2, but has an unusual crystal construction. Crystals are always microscopic, and often form tiny curved public.
a kind of silica within little octahedral crystals in cavities in the andesite of Cerro San Cristobal, Mexico. It may possibly be pseudomorphous.
a white mineral composed of silica; present in volcanic rocks