COESITE

Habit: tabular, high pressure.
Color: colorless.
Luster: vitreous (i.e., glassy).
Streak: white.
Fracture: conchoidal.
Twinning: {011}, {021}.
Diaphaneity: transparent to translucent.
Chemical: resistant to strong mineral acids, attacked by HF and molten alkali-metal hydroxides.

ChEBI: Silicon dioxide is a silicon oxide made up of linear triatomic molecules in which a silicon atom is covalently bonded to two oxygens.