Obsidian (rock)

Obsidian is a naturally occurring volcanic glass formed when lava cools rapidly, preventing crystals from forming. Its smooth, glassy texture is often jet black, though it can have hints of dark brown or green. Because it’s solidified through quick cooling, obsidian is extraordinarily hard and sharp—historically used for cutting tools and arrowheads. It has no crystalline structure, giving it a shiny, mirror-like appearance. Commonly found in volcanic regions, obsidian's unique properties make it valuable in both archaeological artifacts and modern jewelry.