Granite and basalt are excellent examples of coarsely grained igneous rocks. The coarseness of such igneous rocks is a result of magma becoming trapped beneath sediment and stone, which allows the liquid to cool at a slower rate.
Rocks that originate by this slow process are classified as phaneritic. These contrast with aphanitic igneous, which are made up of microscopic grains, and igneous rock that is cooled so quickly it takes on characteristics of glass. The conditions necessary to form phaneritic rock leave it buried beneath the Earth's crust. Over time, wind and water work to erode the mineral material containing this slow-cooled magma, until finally it is exposed to the surface.Learn More
Some uses of igneous rock include serving as material for buildings and roads. Igneous rocks reduced to gravel size serve as ballast for railroad beds. Igneous rocks are also used for countertops, backsplashes and sinks. They can be carved into works of art and weapons.Full Answer >
Examples of igneous rocks include granite, pegmatite, diorite, gabbro, dunite and peridotite. Other examples of igneous rocks are kimberlite, rhyolite, quartz porphyry, dacite, latite, andesite, basalt, obsidian and pumice.Full Answer >
Igneous rocks rarely contain fossils because the formation of a fossil requires sedimentation. A fossil results when the remains of a plant or animal are covered by sediment that hardens, forming the mold that eventually fills with minerals. Igneous rocks form under heat and pressure that destroy organic remnants.Full Answer >
Some examples of intrusive igneous rocks are granite, diorite, syenite, gabbro and pyroxenite. These rocks were formed over eons in magma chambers deep in the earth under high pressure and high temperatures.Full Answer >