lherzolite

thumb|Lherzolite thumb|right|Lherzolite at Etang de Lers, Ariège, France thumb|Garnet lherzolite, a xenolith from a kimberlite pipe, [[Kimberley, South Africa. Field of view ~1.6 cm across. Purplish red = pyrope garnet. Bright green = chromian diopside. Dark greenish-black = orthopyroxene. Olive-green = olivine.]]

Lherzolite is a type of ultramafic igneous rock. It is a coarse-grained rock consisting of 40 to 90% olivine along with significant orthopyroxene and lesser amounts of calcic chromium-rich clinopyroxene. Minor minerals include chromium and aluminium spinels and garnets. Plagioclase can occur in lherzolites and other peridotites that crystallize at relatively shallow depths (20 – 30 km). At greater depth plagioclase is unstable and is replaced by spinel. At approximately 90 km depth, pyrope garnet becomes the stable aluminous phase. Garnet lherzolite is a major constituent of the Earth's upper mantle (extending to ~300 km depth). Lherzolite is known from the lower ultramafic part of ophiolite complexes (although harzburgite is more common in this setting), from alpine-type peridotite massifs, from fracture zones adjacent to mid-oceanic ridges, and as xenoliths in kimberlite pipes and alkali basalts. Partial melting of spinel lherzolite is one of the primary sources of basaltic magma.