5.2 Igneous Rocks

Question 1

Composition

Answer 1

The chemical elements and minerals a rock is made of.

Question 2

Extrusive

Answer 2

Igneous rocks formed on Earth’s surface rather than inside of Earth’s crust.

Question 3

Felsic

Answer 3

Magma or igneous rocks with a high silica (SiO₂) content; felsic rocks are generally light-colored.

Question 4

Intrusive

Answer 4

Igneous rocks formed beneath Earth’s surface.

Question 5

Mafic

Answer 5

Magma or igneous rocks with a low silica (SiO₂) content; mafic rocks are generally dark in color.

Question 6

Texture

Answer 6

Refers to the size of crystals in a rock. Coarse-grained texture has large mineral grains, and fine-grained texture has microscopic grain sizes.