Here's why:
* Crystal Growth: Mineral crystals form from the cooling and solidification of molten rock (magma or lava). The slower the cooling process, the more time the atoms have to arrange themselves into larger, more organized crystal structures.
* Intrusive vs. Extrusive:
* Intrusive igneous rocks (like granite) cool slowly beneath the Earth's surface, giving ample time for large crystals to grow.
* Extrusive igneous rocks (like basalt) cool quickly at the surface, resulting in smaller, less visible crystals.
Therefore, the large crystals in igneous rocks are a direct result of slow cooling.
