Synonym Discussion of NORMAL. regular, normal, typical, natural mean being of the sort or kind that is expected as usual, ordinary, or average. regular stresses conformity to a rule, standard, or pattern.
Extrusive Igneous Rocks. VOLCANOES! Extrusive igneous rocks form when magma reaches the Earth's surface a volcano and cools quickly. Most extrusive (volcanic) rocks have small crystals. Examples include basalt, rhyolite, andesite, and obsidian. Mineral Photos courtesy of R.Weller/Cochise College.
Obsidian and basalt. If the magma cools quickly, small crystals form in the rock. This can happen if the magma erupts from a volcano. Obsidian and basalt are examples of this type of rock. They are called extrusive igneous rocks because they form from eruptions of magma.ranite and gabbro are examples of this type of rock. They are intrusive igneous rocks because they form from magma underground. Unlike sedimentary rocks, igneous rocks do not contain any fossils. This is because any fossils in the original rock will have melted when the magma formed. 1  Page. 2  1. 3  2.