Obsidian

About Obsidian

A natural volcanic glass formed when silica rich lava cools too quickly for crystals to grow. It breaks with a conchoidal fracture that leaves edges far sharper than steel. Prehistoric people traded it over great distances for tools and blades. The Aztecs edged wooden clubs and weapons with obsidian blades. Snowflake obsidian contains white patches of cristobalite. Some surgeons have used obsidian scalpels for very fine incisions.