Ultramafic rock
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Ultramafic rocks are igneous and meta-igneous rocks with a very low silica content, generally >18% MgO, high FeO, low potassium, and are usually composed of greater than 90% mafic minerals. Earth's ma
Peridotite, a type of ultramafic rock dominated by olivine
Pyroxenite, a type of ultramafic rock dominated by pyroxene minerals
Archean komatiite from the Komati Formation in the Komati River Valley, South Africa, showcasing spinifex texture.
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
Ultramafic rock
…layers. Such cumulate rock types do not represent the chemistry of the magma from which they crystallized. The ultramafic intrusives include the dunites, peridotites and pyroxenites. Other rare varieties include troctolite which has a greater percentage of calcic plagioclase. These grade into the anorthosites. Gabbro…
Peridotite xenolith from the Kilbourne Hole maar, New Mexico.
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