How are intrusive igneous rocks formed?

Intrusive Igneous Rocks. Intrusive, or plutonic, igneous rocks form when magma cools slowly below the Earth's surface. Most intrusive rocks have large, well-formed crystals. Examples include granite, gabbro, diorite and dunite. Mineral Photos courtesy of R.Weller/Cochise College. read more

Igneous rocks are of two types, intrusive (plutonic rocks) and extrusive (volcanic rocks). Intrusive Igneous Rocks; Intrusive igneous rocks are formed when the magma cools off slowly under the earth’s crust and hardens into rocks. Gabbro and granite are examples of intrusive igneous rocks. read more

Intrusive, or plutonic, igneous rocks form when magma cools slowly below the Earth's surface. Most intrusive rocks have large, well-formed crystals. Examples include granite, gabbro, diorite and dunite. read more

Compared to intrusive rock, this type of igneous rock cools and crystallizes at a much faster rate due to it being exposed to air or water, which results in it being fine-grained. How igneous rocks are formed. read more

Intrusive Rocks Igneous rocks which form by the crystallization of magma at a depth within the Earth are called intrusive rocks. Intrusive rocks are characterized by large crystal sizes, i.e., their visual appearance shows individual crystals interlocked together to form the rock mass. read more