Lechatelierite is a very big and hard word that sounds like something your grown-ups might say when they want to sound smart, but don't worry, it's not too hard to understand.
It's actually a type of rock, but not just any old rock! It's a special kind of rock called a mineral. This mineral is made of something called silica, which is a type of material that is made up of some very tiny pieces called atoms.
Lechatelierite is special because it's formed in a very cool way. Sometimes, when there is a big, hot explosion like a volcano or a meteor hitting the ground, the heat and pressure are so intense that they can turn sand into this special mineral. It's kind of like when you bake cookies in the oven, but way bigger and hotter!
The lechatelierite mineral is really pretty to look at, too. Often, it's clear like ice, but can also have some pretty colors like green or purple, depending on what type of minerals are mixed in with it.
So, to sum up, lechatelierite is a special kind of rock that is formed from sand during big, hot events like volcanoes or meteors, and it's made of a material called silica which has tiny little pieces called atoms. And it's really pretty, too!