Dunite


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dunite

[′dü‚nīt]
(petrology)
An ultrabasic rock consisting almost solely of a magnesium-rich olivine with some chromite and picotite; an important source of chromium.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Dunite

 

(named after Mount Dün, New Zealand), a magmatic rock that is ultrabasic and black, dark-green, or light-green in color; it consists of 85 to 100 percent olivine and contains chromite as an admixture, sometimes together with magnetite. Dunite is very rich in magnesium and contains little silica. It is rarely found in an unchanged state; it is usually more or less serpentinized and even totally transformed into serpentine. Dunite is linked by gradual transitions with several gabbros and pyroxenites. Dunites are widespread; they usually form sills, parallel lenses, and intersecting pipes; more seldom they form large intrusive bodies (for example, the dunite belts along the entire Urals and the Mugodzhary). It is thought that dunites are chunks of the upper mantle that were tectonically introduced into the young rocks of the upper part of the earth’s crust. Deposits of various minerals (including chromites, platinum, nickel, cobalt, talc, and chrysotile-asbestos) are associated with dunite. Dunite is used for the manufacture of fire-resistant materials.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
This is why, for the present study, dunite is an important benchmark, but the researchers focus on basalt as a more sustainable option.
Pakistan has enormous wealth of decorative and building stones such as granites, diorite, dunite, tanatite, pyroxenite, serpentite, gabbro, onyx, marble of different shades, recrystallized limestone, fossiliferrous limestone, sand stone, magnesium sandstones etc.
Bits of these rocks-peridotite, dunite, lherzholite and others - may be squeezed to the surface when continental plates collide with oceanic plates, or, less often, when the interiors of continents thin and develop rifts.
The prospect returned values up to 2.27 grams of platinum from chromium iron oxides outcropping in dunite. The target at Suzie Mountain is 50 meters by 100 meters, with greater than 50 parts-per-billion platinum in soils with grades up to 432 parts-per-billion platinum.
Dun (of Dunite fame) Ophiolite belt of South Island, New Zealand.
The Piedmont Uplands along the Maryland-Pennsylvania border contain Precambrian-age rocks, including gneisses, quartzites, schists and marbles, which are locally intruded by ultramafic peridotite (dunite) and pyroxenite.
4:15 Metamorphism of Dark Ridge Dunite, North Carolina.
Dunite and peridotite comprise about 1,200 m of the 1,800 m thickness of the layered series.
We can then ask, are there dunite channels wide enough and numerous enough to account for chemically isolated transport of melt from deep in the melting region to the base of the crust?