Extrusive igneous rocks are erupted onto the surface or into the atmosphere. Extrusive igneous rocks are also termed volcanic rocks—named for Vulcan, the Roman god of fire. Volcanic rocks have generally smaller crystal size and usually have a very-fine-grained or glassy groundmass that formed due to rapid cooling at the time of eruption.
Igneous rock, any of various crystalline or glassy rocks formed by the cooling and solidification of magma, which is a hot (600 to 1,300 °C, or 1,100 to 2,400 °F) molten or partially molten rock. Igneous rocks constitute one of the three principal classes of rocks, the others being metamorphic and sedimentary.
Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface. Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies.Intrusive Igneous Rocks:Intrusive, or plutonic, igneous rock ...
Intrusive igneous rocks crystallize below Earth's surface, and the slow cooling that occurs there allows large crystals to form. Examples of intrusive igneous rocks are: diabase, diorite, gabbro, granite, pegmatite, and peridotite. Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals.
Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in a terrestrial planet 's mantle or crust.