Obsidian is a natural glass that is formed from volcanic lava that cooled quickly.
Black is the most common color but can also be found in shades of brown and gray. Red is a rare color. The color can be uniform, spotted or striped and sometimes inclusions can create a metallic sheen.
Obsidian has been sourced from Japan, Hawaii, Java, Mexico, Iceland, Hungary, as well as Arizona and New Mexico.
Many prehistoric tools such as arrowheads, jewelry and even mirrors were made with Obsidian. Types of Obsidian are rainbow, snowflake, and Apache tears.