Peridotite
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Peridotite is a dense, phaneritic igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magne
Typical peridotite sample (dunite, left) and large olivine crystal (right)
Olivine in a peridotite weathering to iddingsite within a mantle xenolith
Serpentinized and carbonated peridotite
Pyroxenite
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Pyroxenite is an ultramafic igneous rock consisting essentially of minerals of the pyroxene group, such as augite, diopside, hypersthene, bronzite or enstatite. Pyroxenes have the general formula XY2O
Pyroxenite from Rustenburg, South Africa
Metamorphosed (serpentinized) clinopyroxenite, made of green diopside, from the Shetland ophiolite, Unst, Scotland