Why do intrusive igneous rocks have large crystals?
Hereof, what is an igneous rock with large crystals?
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 diorite, gabbro, granite, pegmatite, and peridotite. Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals.
One may also ask, why are igneous rocks important? Igneous rocks are also very important because their mineral and chemical makeup can be used to learn about the composition, temperature and pressure that exists within the Earth's mantle. They can also tell us much about the tectonic environment, given that they are closely linked to the convection of tectonic plates.
One may also ask, what does grain size tell you about igneous rocks?
Grain size tells us much about the crystallisation of an igneous rock. It is also the most noticeable feature and thus provides our first criterion for classification. When a large magma body remains underground, it is insulated from heat loss and cools and solidifies very slowly.
Why are some intrusive rocks found above ground?
Intrusive rocks are formed by solidification of lava beneath the Earths surface, in environments that allow slow cooling, giving ample time for mineral crystals to form, a good example is a granite. Technically, intrusive rocks don't reach the Earth Surface, they are exposed as a result of geologic activitie.