Intrusive igneous rock forms when magma pushes into surrounding rock below the surface of the Earth. Examples of intrusive igneous rocks are granite and diorite.
Forms when sediments get buried, compacted, and cemented together by Quartz or calcite. Examples of these rocks consist of mudstone, siltstone, and shale.
This type of rock forms from the remains or fossils of once living animals and plants. Coquina, chalk, and coal are all examples of organic sedimentary rocks.