Flint is a hard, glassy rock that was crucial to human survival for hundreds of thousands of years. When you strike flint against steel or another piece of flint, it creates sparks that can start a fire. Before matches were invented in the 1800s, people relied on flint to make fire for cooking and warmth.

Flint also breaks in a special way that creates extremely sharp edges. Ancient people discovered they could chip away at flint to make tools like arrowheads, knife blades, and scrapers. A skilled craftsperson could turn a rough chunk of flint into a razor-sharp spear point. Archaeological sites around the world contain countless flint tools, some over a million years old.

The rock forms naturally in chalk and limestone deposits and comes in various colors, usually gray, black, or brown. If you've ever seen old-fashioned firearms called flintlock rifles, they got their name because they used a piece of flint to create the spark that fired the gun.

Today, geologists and rock collectors still value flint for its distinctive appearance and historical importance. You might find pieces of flint along certain beaches or riverbeds, recognizable by their smooth, glassy surface when freshly broken.