Obsidian (named after the roman, Obsius) is a volcanic glass.
Its color is black, grey, brown, green and can be gold or silver due to inclusions.
Transparent to opaque.
Obsidian has a hardness of 5-5 1/2.
Obsidian has a density of 2.35-2.60.
Obsidian is singly refractive with an R.I. range of 1.45 to 1.55.
- Snowflake obsidian is the trade name for an obsidian with grey-white, ball shaped inclusions of Spherulites found in Mexico and the United States.
Deposits are found in the United States, Mexico, Japan, Italy, Iceland, Indonesia, and Equador.