Rainbow obsidian

Rainbow Obsidian is an obsidian variety in which all colors except yellow are included in the black or gray base, sometimes in pronounced bands. These may or may not have spangles, but are usually tumbled into irregular gemstones in either case. Like other obsidian, the rainbow variety is hard but brittle, and rarely finds use in places that will receive some wear. A typical specimen has a base value of 50gp.