What do all igneous rocks have in common? Variety of Igneous Rocks: There are many different types of igneous rocks based on where they formed and what minerals they contain. They can be extrusive or intrusive, depending on whether they form below the ground or on the surface. They can als...
themselves into minerals, so instead become natural glass. Volcanic ash is a dust-sized form of obsidian. SEDIMENTARY ROCKS Deposits of sediment which have been compressed or precipitated and cemented together into hard layers. Clastic Rocks