Lherzolite

It is a coarse-grained rock consisting of 40 to 90% olivine along with significant orthopyroxene and lesser amounts of calcic chromium-rich clinopyroxene.

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.

The name is derived from its type locality, the Lherz Massif (an alpine peridotite complex, also known as orogenic lherzolite complex), at Étang de Lers, near Massat in the French Pyrenees; Étang de Lherz is the archaic spelling of this location.

The layers represent partial melts extracted from the host peridotite during decompression in the mantle long before emplacement into the crust.