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Peridotite is the dominant rock of the upper part of Earth's mantle. The compositions of peridotite nodules found in certain basalts are of special interest along with diamond pipes , because they provide samples of Earth's
Peridot can be found in mafic and ultramafic rocks occurring in lava and peridotite xenoliths of the mantle. The gem occurs in silica-deficient rocks such as volcanic basalt and pallasitic meteorites. Along with diamonds, peridot is one of only two gems observed to be formed not in Earth's crust, but in the molten rock of the upper mantle. [1]
Pillow lavas and oceanic basalts are among the most common rocks found within the formation. There are a number of exposures that straddle the ancient Mohorovičić discontinuity . Metamorphosed peridotite , in the form of a serpentine rock, is an indicator of the formation.
Peridotite, a type of ultramafic rock. Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are usually composed of greater than 90% mafic minerals (dark colored, high magnesium and iron content).
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 onto continental crust by obduction during continental or island arc collisions . It is also found in alpine peridotite massifs that represent slivers ...
In the area of Ogo dour at the Northern reaches of Predannack, dunite, a highly depleted peridotite derivative which consists of almost pure olivine, is found. Earlier theories, most notably the BGS publication "Lizard & the Meneage" [ 4 ] that summarised thinking up to the point of publication, proposed that the serpentinite body represented ...
Serpentine soil is an uncommon soil type produced by weathered ultramafic rock such as peridotite and its metamorphic derivatives such as serpentinite. More precisely, serpentine soil contains minerals of the serpentine subgroup, especially antigorite, lizardite, and chrysotile or white asbestos, all of which are commonly found in ultramafic ...
Harzburgite may also be found in some Alpine peridotite massifs that consist mostly of lherzolite. Alpine or orogenic lherzolites represent subcontinental mantle lithosphere (the upper mantle below continental crust) exposed during the plate tectonic collision of continental plates.