Peridotitt

Peridotitt is a term used in some languages as a variant spelling of peridotite, a coarse‑grained ultramafic igneous rock. In English, the standard term is peridotite; peridotitt may appear as a transliteration or regional spelling. Peridotite forms the compositionally light end of mantle rocks and is dominated by olivine and pyroxenes, with accessory minerals such as spinel or garnet.

The rock occurs in several subtypes, primarily dunite (mostly olivine), harzburgite (olivine and orthopyroxene), and lherzolite (olivine, orthopyroxene, and clinopyroxene). It is typically coarse-grained due to slow cooling and high-temperature formation in the mantle. Peridotite can be altered by surface or tectonic processes, producing serpentinite through hydration, or it can be exposed at the surface in ophiolites and ultramafic intrusions.

Geologically, peridotite is significant because it is representative of the Earth's upper mantle material and provides insights into mantle composition, partial melting processes, and tectonic dynamics. It can host sulfides and chromian spinels, which may concentrate economically valuable elements such as platinum-group elements in certain contexts. Because of its mantle origin, peridotite and its variants help scientists understand crust–mantle interactions, subduction, and mantle convection.

In summary, peridotitt refers to a regional spelling of peridotite, a mantle-derived ultramafic rock essential to understanding Earth's interior. See also ultramafic rocks, serpentinite, ophiolites.