Dunite
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Dunite is an igneous, plutonic rock, of ultramafic composition, with coarse grained or phaneritic texture. The mineral assemblage is typically greater than 90% olivine with minor pyroxene and chromite. Dunite is the olivine rich endmember of the peridotite group of mantle derived rocks. Dunite and other peridotite rocks are considered to represent the Earth's mantle. Dunite is rarely found within continental rocks, but where it is found, it typically occurs at the base of ophiolite sequences where slabs of mantle rock from a subduction zone have been thrust into continental crust by obduction during continental or island arc collisions (orogeny). Dunnite weathers to form serpentine.
Dunite was named by the Austrian geologist, Ferdinand von Hochstetter in 1859 after Dun Mountain behind Nelson, New Zealand. Dun Mountain was given its name because of the dun colour of its vegetation which is itself a reflection of underlying ultramfic rocks.
Not to be confused with the explosive Dunnite