Obsidian Bracelet with Evil Eye Charm Chemical Formula: R3R2(SiO4)3 (R =

Chemical Formula: R3R2(SiO4)3  (R = Various elements that contribute to the species of garnet

heulandite

The amount of cobalt contained within the specimen usually determines how pink the specimen is

Opal is a form of amorphous silica

and gray hues

Obsidian Bracelet with Evil Eye Charm Chemical Formula: R3R2(SiO4)3 (R =Stone: Obsidian Bead: Round 6mm Average Length: 7 in. Obsidian is a naturally occurring form of volcanic glass. Obsidian forms as lava cools very rapidly and is not considered a mineral as its lacks any form of crystal structure. It is said that obsidian is actually a mistranslation from Pliny the Elder's Natural History. The first spelling of the word was obsian. Obsidian has been used to make surgical blades and arrowheads throughout history because