Peridot

Peridot is formed deep within the mantle region, unlike most gemstones that are formed in earth's crust. Peridot crystals form in magma from the upper mantle and are brought to the surface by tectonic or volcanic activity where they are found in extrusive igneous rocks such as Basalt, Gabbro, Dunite, Diabase, and Peridotite. Many people are familiar with Olivine because it is the mineral of a very popular green gemstone known as Peridot.