Obsidian is a type of black or dark glass formed from cooling lava. So if you find a shiny, hard, dark piece of glass next time you’re hanging around a volcano, it’s probably a piece of obsidian. The word obsidian essentially means “stone of Obsius.” So who was Obsius? Think of an obsidian arrowhead, blade or mirror.
How do I pronounce basalt?
What part of speech is Obsidian?
noun. a volcanic glass similar in composition to granite, usually dark but transparent in thin pieces, and having a good conchoidal fracture.
