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Earth Materials
Minerals | Rocks

Volcanic Products
Rate of Cooling

Igneous rocks form through crystallization of minerals from magmas (molten rocks). Their textures refer to the size and arrangement of the minerals that make up the rock and reveal about how the rock formed. For example, the size of crystals in igneous rocks primarily reflects the rate of cooling. Rapid cooling creates tiny crystals and freezes the liquid to glass, while slower cooling forms coarse-grained igneous rocks.

Gas content of magmas