Crystal Black Agate

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). See also the Agate mineral page.