Cristobalite
WordNet
noun
(1) A white mineral consisting of silica; found in volcanic rocks
WiktionaryText
Noun
- A mineral of volcanic rocks that solidified at a high temperature. Cristobalite is chemically identical to quartz, with the chemical formula SiO2, but has a different crystal structure. Crystals are always microscopic, and usually form small rounded masses.
See also
- Wikipedia article on Silicon dioxide minerals
- Silicate, Silica group