Crystal Black Onyx

Chemical Formula

SiO₂

Color

White, Blue, Red, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Black, Banded, Multicolored

Hardness

7

Crystal System

Hexagonal

Refractive Index

1.54 - 1.55

SG

2.63 - 2.65

Transparency

Translucent

Double Refraction

.009

Luster

Vitreous

Cleavage

Indiscernible

Mineral Class

Quartz (Chalcedony).