Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
tetragonaluncommonSilicates
Cristobalite
SiO2
This specimen features white, spherical to radiating aggregates of cristobalite embedded within a dark, glassy obsidian matrix.
Cristobalite Physical Properties
Mohs Hardness
6.5Crystal System
tetragonalLuster
vitreousStreak Color
whiteCleavage
poor/indistinct on {111}Fracture
conchoidalSpecific Gravity
2.2Colors
white, colorless, grayTransparency
transparentType Locality
Canyon Butte occurrence (Couger Butte), Canyon Butte, Siskiyou County, CaliforniaMineral Group
SilicatesUses
scientific research, ceramic component, refractory materialAssociated Minerals
obsidian, tridymite, quartz, feldsparRarity
uncommonGeological Context
Cristobalite is a high-temperature polymorph of silica that forms in volcanic rocks, such as rhyolite and obsidian, often as spherulites or lining vesicles, crystallizing from silica-rich magmas.
