peridotite


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peridotite

(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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Peridotite

 

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.

peridotite

[pə′rid·ə‚tīt]
(petrology)
A dark-colored, ultrabasic phaneritic igneous rock composed largely of olivine, with smaller amounts of pyroxene or hornblende.
References in periodicals archive ?
If all goes well, in three years, we will be able to start cutting down carbon emission levels in Oman," the Earth scientist said, adding that they have plans to export peridotite rocks globally so that everyone can benefit from it.
This interaction only requires that holes be drilled into the peridotite rock.
Three geological areas may contain asbestos: the Boghen unit, the Peridotite massifs, and the Northern Caledonian metamorphic complex (Figure 1).
The volcanic action preferentially removed aluminum, calcium and iron-rich minerals from the deep, leaving behind a slag of peridotite.
Melting of phlogopite-bearing peridotite produces potassic rather than sodic magmas, but melting of amphibole- and clinopyroxene-bearing lherzolite yields magmas with low CaO/[Al.
The host rock consists mainly of serpentinized peridotite (harzburgite).
These peridotite massifs are 150 km away from one another and stand on an E-W trend on both sides of the Quaternary volcanic cordillera.
A diamond drilling programme has uncovered a new ultramafic, serpentinized peridotite, containing some sulphide mineralization.
As with quartz, the Al that formed gibbsite could have come from the peridotite and the accompanying minerals such as calcic feldspar.
INCO, there are three broad types of basic rocks, namely: Type A, unserpentinized peridotite; Type B, weakly serpentinized and crudely grained peridotite; and Type C, strongly serpentinized and crudely grained peridotite.
The company holds 70 square kilometers of concessions within the Dominican Peridotite Belt, which contain nickel laterite formations (see National Geology map of the Dominican Republic).