Some peridotites contain significant amounts of chromite. Some of these form when a subsurface magma slowly crystallizes. During the early stages of crystallization, the highest-temperature minerals such as olivine, orthopyroxene, clinopyroxene, and chromite begin to crystallize from the melt. The crystals are heavier than the melt and sink to the bottom of the melt. These high-temperature minerals can form layers of peridotite on the bottom of the magma body. This can form a layered deposit where up to 50% of the rock can be chromite. These are known as “stratiform deposits.” Most of the world’s chromite is contained in two stratiform deposits: the Bushveld Complex in South Africa and the Great Dyke in Zimbabwe.

Another type of chromite deposit occurs where tectonic forces push large masses of oceanic lithosphere up onto a continental plate in a structure that is known as an “ophiolite.” These ophiolites contain significant amounts of chromite and are called “podiform deposits.”