from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A dense igneous rock that consists mainly of olivine and is a source of magnesium.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A type of igneous rock with a coarse-grained or phaneritic texture.
from The Century Dictionary and Cyclopedia
- n. A rock consisting essentially of a crystalline granular mass of olivin with chromite or picotite, containing also frequently more or less of various other minerals, alteration products of the olivin. Dunite appears to be frequently more or less altered into serpentine.
C peridotite and dunite the upper mantle is composed of ultramafic rock called peridotite which is mostly olivines and pyroxenes.
The Ural Mountain deposits of Russia are gold - and platinum-bearing placers, in streams which drain areas of dunite rock containing minute quantities of native platinum.
The zones are separated by a horizon of disseminated chromite hosted within peridotite and dunite.
One shows how dunite terrain is desert even if well watered: a dunite massif in New Zealand adjoins another mountain, and at the joint, the other mountain is green, the dunite is orange.
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 process of mineral carbonation on ultramafic rocks such peridotite, dunite and lherzholite takes thousands of years for large quantities of carbon dioxide to be soaked up.
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.
Chromite mineralization is hosted within a continuous northeast to southwest-trending ultramafic sill complex consisting of variably altered dunite, peridotite and pyroxenite.
C) peridotite and dunite (the upper mantle is composed of ultramafic rock called peridotite which is mostly olivines and pyroxenes.
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