Igneous Rocks

rock

A naturally formed mixture that can contain minerals, rock fragments, and volcanic glass bound together.

intrusive igneous rock

Igneous rocks that form within Earth’s crust from magma that cools slowly.

extrusive igneous rock

Igneous rocks that form from lava or ash that erupts onto Earth’s surface and cools rapidly.

mixture

A combination of two or more substances that can be physically separated.

grain size

The size of the mineral crystals in a rock.

Bowen’s reaction series

A series describing the order in which silicate minerals crystallize from magma as it cools.

mafic magma

A type of magma that is rich in magnesium and iron, producing mafic rocks.

intermediate magma

A type of magma with a composition between mafic and felsic magmas.

felsic magma

A type of magma that is rich in silica, producing felsic rocks.

fine-grained texture

A texture of igneous rocks that indicates rapid cooling, resulting in small crystals.

coarse-grained texture

A texture of igneous rocks that indicates slow cooling, allowing large crystals to form.

vesicular texture

A texture resulting from trapped gases escaping during an eruption, creating holes in the rock.

porphyritic texture

A texture that results when minerals crystallize at different rates, leading to different-sized crystals.

volcanic bombs

Irregularly shaped rocks formed from solidified blobs of lava that erupt into the air.