Dunite


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Related to Dunite: Harzburgite, pyroxenite, wehrlite, Rhyodacite

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.

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.

References in periodicals archive ?
Nickel, copper and platinum group element mineralization is hosted in dunite and herzolite within the Tonsina Ultramafic Complex.
In addition to dissolution channeling, dunite formation may also have been influenced by other processes including focusing of melt in zones of localized deformation, "suction" of melt into the region of plate separation beneath ridges, focusing of melt flow beneath permeability harriers, especially near the top of the upwelling mantle column, and perhaps the formation of dunite in porous reaction zones around melt-filled cracks.
The alluvial deposits on Dime Creek are composed of mostly volcanic andesite and basalt sand and gravel with occasional cobbles of intrusive olivine dunite.
In some cases the penetration of Dunite dykes that have cut the Harzburgites floation direction are also observed.
Nickel, copper, and platinum group element mineralization is hosted in dunite and lherzolite within the Tonsina Ultramafic Complex.
1997) show a textural division that includes an upper part (Zone A), characterized by spinifex-textured rock, and a lower part (Zone B) containing a high proportion of equant olivine crystals resembling various peridotite to dunite cumulates (Fig.
The joint venture effort over the last two years consisted of $3 million worth of exploration on the Fish Lake and Dunite Hill prospects.
1 by 1 km consist of(meta)harzburgite and minor dunite with associated gabbro (#4 in Fig.
This project is an extension of previous work on the Dark Ridge dunite in Jackson County, North Carolina.
E[acute accent]Mooihoek Platinum Pipe Deposit contains the remnants of a platinum-rich dunite pipe of which platinum makes up 97.
The intervals sampled and reported by Noront include both massive chromitite and zones of intercalated beds of chromitite and heavily disseminated chromite hosted by talc-altered dunite and peridotite.
Near Asbestos, he recognized that the peridotite, chromite-beating dunite, pyroxenite, gabbro, diabase, porphyrite, hornblende granite, and aplite are all parts of a thick sill.