Igneous Bedrock
In Latin, "igneous" means fire. It is the root of ignite and ignition. Igneous rocks were once melted rock. They were liquid. They lost their crystal structure. They flowed from one place to another in the Earth's crust (generally only a few miles).
The type of rock that was melted to become the fluid (molten rock) determined the chemistry of the melt and the eventual chemistry of the igneous rock that would harden when the molten mass cooled.