Cristobalite
Chemical Formula	SiO2
Species	Silicates
Crystal System	Tetragonal
Mohs Scale	6-7
Specific Gravity	2.32-2.36
Color	Colorless, white
Streak	White
Luster	Vitreous
Refractive Index	n = 1.487 n = 1.484
Diaphaneity	Transparent, Translucent
Fracture	Conchoidal
Crystal Habit：Octahedra or spherulites up to several cm large
Geological Setting：Individual crystals in vesicles and lithophysae. Common constituent of opal (opal-C and opal-CT) in sedimentary rocks and silicious sinter.