Conchoidal fracture

Imagine you have a yummy chocolate chip cookie. If you break it in half, it will most likely look like it has two straight edges where it broke. But if you drop the cookie on the floor, the broken pieces might have much curvier edges that look kind of like tiny pieces of glass. That's what a conchoidal fracture looks like when something is broken - like a wavy or curved line instead of a straight one.

Now, imagine that cookie is actually a piece of rock. If you hit it hard enough to break it, the rock might have a conchoidal fracture. This kind of fracture happens when something is strong enough to break the rock, but the way the rock breaks creates those curved lines. It looks a bit like the inside of a seashell or a very smooth glass bottle.

Conchoidal fractures happen because of the way that rocks are made up. Rocks are made of tiny crystals, and when rocks break, those crystals break apart in a special way. The force of the break causes some of the crystals to shatter, and the way they shatter is what makes the curved lines.

People who study rocks use conchoidal fractures to figure out what kind of rock they are looking at. Different kinds of rocks have different patterns of conchoidal fractures. If you ever break a rock and it has a curvy edge like that, you can use that clue to help you figure out what kind of rock it is.