Here's a breakdown:
* Igneous rocks form when molten rock (magma or lava) cools and solidifies. The process of crystallization involves the arrangement of atoms and molecules into a specific, ordered structure, forming minerals. This can happen:
* Intrusively: When magma cools and solidifies beneath the Earth's surface, forming intrusive igneous rocks like granite.
* Extrusive: When lava erupts onto the surface and cools, forming extrusive igneous rocks like basalt.
* Metamorphic rocks are formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are subjected to intense heat and pressure deep within the Earth's crust. This process doesn't involve crystallization from a melt. Instead, the existing minerals within the rock are recrystallized or transformed into new minerals without melting.
Key Difference:
* Igneous rocks form from the cooling and solidification of molten rock, while metamorphic rocks form from the transformation of existing rocks under heat and pressure without melting.
