Obsidian nodules and flakes have a smooth, glassy texture and sharp edges. At a microscopic level, obsidian flakes can be sharper than instruments made of surgical steel. While obsidian tools are ...

Obsidian is a black, often translucent rock. Volcanic eruptions sometimes ooze out magma that turns into this natural glass as it cools. Obsidian is hard, durable and can be worked to a razor ...