SiO2Trigonal
Onyx
SiO2
SilicatesChemical FormulaSiO2
Crystal SystemTrigonal
Mohs Hardness7
Specific Gravity2.6
ColorBlack and white banded
LusterVitreous
StreakWhite
CleavageNone
FractureConchoidal
Occurrence
Banded variety of chalcedony with parallel bands. Used in cameos and intaglios.