Is andesite intrusive or extrusive?
Intrusive or extrusive describe properties of an igneous rock. An intrusive rock is formed within the crust and it insulated and cooled slowly. Some examples of an intrusive rock include diorite, granite, gabbro, and periodite. They have large grains because they have more time for growth. On the other hand, extrusive rocks cool at the surface rapidly. They are comprised of tiny crystals and/or glass. Some examples include rhyolite, andesite, and basalt.
Both andesite and diorite are igneous rocks with an intermediate color index. Diorite; however, is intrusive and phaneritic, whereas andesite is aphanitic and extrusive. Andesite is said to be the extrusive equivalent of diorite. Diorite is made up of plagioclase feldspar and ferromagnesian mineral crystals, mainly amphibole. Contrarily, andesite may resemble rhyolite, meaning it presents a need for microscopic examination to see its mineral crystals. The two have a composition of plagioclase feldspar and amphibole…