Igneous Rock

Extrusive Igneous Rock

Extrusive igneous rocks forms when lava, which is magma that has risen to the Earth's surface through a volcano, cools and solidifies; the rocks formed are smooth and noncrystalline. Basalt, shown here, is an extrusive igneous rock that is formed when magma erupts to the Earth's surface as lava. [LM] {CC}