Cristobalite nodules in obsidian from central Utah. This combination is
called "snowflake" obsidian.
CHEMISTRY SiO2 Silicon oxide
CRYSTALLOGRAPHY Tetragonal (pseudo cubic)
CRYSTAL GROWTH AND HABITS Cristobalite is found as dendritic or spherulitic masses, it is also found as fibrous to massive.
COLOR AND OTHER OPTICAL PROPERTIES White to light gray; translucent to opaque
HARDNESS 6 -7
SPECIFIC GRAVITY 2.3 - 2.4
LUSTER Vitreous to dull
STREAK White
BREAKABILITY Uneven to splintery fracture; brittle
OCCURRENCE Cristobalite is found in siliceous volcanic rocks.
ASSOCIATED MINERALS Quartz, Tridymite, Sanidine, Opal