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(pĕr'ēdō`tīt): see olivineolivine
, an iron-magnesium silicate mineral, (Mg,Fe)2SiO4, crystallizing in the orthorhombic system. It is a common constituent of magnesium-rich, silica-poor igneous rocks; metamorphism of some high magnesium sediments also can form olivine.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



an ultrabasic intrusive rock that is chiefly composed of olivine and pyroxene and sometimes contains hornblende. The olivine and pyroxene contents range from 70 to 30 percent and 30 to 70 percent, respectively; peridotite also contains 40 to 46 percent SiO2 and 34 to 46 percent MgO. Among the accessory minerals found in peridotite are magnetite, ilmen-ite, pyrrhotite, chromite, spinel, and garnet. In addition, peridotite sometimes contains platinum and certain nickel minerals.

Peridotite’s color is dark, usually green or greenish gray. When it is highly serpentinized with olivine and pyroxenes, it alters to serpentinite. Peridotite in combination with orthorhombic pyroxene is called saxonite, or harzburgite; with monoclinic pyroxene, wehrlite; and with both rhombic and monoclinic pyroxene, websterite, or lhertzolite. Peridotite in association with other ultrabasic and with basic rocks forms extensive belts and zones that are characterized by deposits of commercial minerals, including chromite, platinum ores, silicate nickel ores, chrysotile asbestos, and talc.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A dark-colored, ultrabasic phaneritic igneous rock composed largely of olivine, with smaller amounts of pyroxene or hornblende.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
An important point to also cover with Year 11 EES students is that most of the oceanic lithosphere is rigid upper mantle peridotite, similar in composition to the underlying asthenosphere.
All data from the literatures: river [3, 4, 11, 12]; ocean water [13-16]; oceanic sediment [6, 7, 12, 17]; hydrothermal sulfide [6, 18-20]; hydrothermal fluid [6, 7, 19-21]; Fe-Mn noddle and crust [8, 22-24]; deposit [25-31]; banded Fe formations [32-42]; carbonate rock [36, 43, 44]; loess/dust [6, 31, 45]; shale [6]; metamorphose rock [46]; basalt [32, 33, 45, 47-53]; mantle peridotite [32, 33, 45, 47-52, 54, 55]; meteorolite [24, 33, 34, 49, 50, 56-62].)
According to the lead scientist, peridotite rocks commonly found just under the crust of the earth could soak up the planet's entire carbon dioxide emissions, even without being mined, when it comes in touch with water.
Ayday, Statistical analysis of discontinuity parameters of Golbasi (Ankara) andesites, Supren (Eskisehir) marble and Porsuk Dam (Eskisehir) peridotite [Ph.D.
Jeanloz, "Equations of state of the high-pressure phases of a natural peridotite and implications for the Earth's lower mantle," Earth and Planetary Science Letters, vol.
The drilling also indicated that sulphides are regularly present in altered peridotite and pyroxenite gneisses underlying the mineralized laterite.
The measurements on ultrabasic rocks were carried out in the peridotite Balmuccia Massif in the Ivrea zone (northern Italy) which represents subcrustal lithospheric mantle material.
In addition to many of the popular gems, there are lesser-known stones to choose from, such as morganite, spinel, peridotite, and tanzanite--believed to have been discovered by the Masai.
The risk increased with serpentinite surface, proximity to serpentinite quarries and distance to the peridotite massif.
The gems form deep in cratons, embedded in rock called peridotite. Fast-moving volcanic eruptions pierce the cratons, dragging pieces of peridotite set with diamonds from the walls of the conduits and belching them, along with ash and residue, across the surface.