Long ago, in Russia’s distant Northwest, a bird pooped. But this was not just any old splat of excrement. The feces landed on a very hot rock. It lay atop an underground coal fire. The intense heat quick-baked the poop. And that caused one of the substances previously dissolved in the feces to crystallize. With that, a new mineral was born.
Minerals are substances with a distinct chemical recipe. And the atoms of each mineral will always arrange themselves exactly the same way.
You’d expect to find crystals in rocks. You’d expect to find them in caves and mines. You would not expect to find one in baked bird poop.