Geology Types of rock Igneous rock
 Igneous rock is rock that has been made by volcanic action. Igneous rock formed from magma that has become solid inside the earth is called intrusive igneous rock. Igneous rock formed from lava that has become solid on the outside of the Earth is called extrusive igneous rock. This can happen because of the eruption of a volcano. Some extrusive igneous rock types are basalt, andesite, rhyolite, tuff, obsidian, and pumice. Examples of intrusive igneous rock types are gabbro, diorite, and granite.