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pyroxene

Definitions

  • WordNet 3.6
    • n pyroxene any of a group of crystalline silicate mineral common in igneous and metamorphic rocks
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Webster's Revised Unabridged Dictionary
    • n Pyroxene (Min) A common mineral occurring in monoclinic crystals, with a prismatic angle of nearly 90°, and also in massive forms which are often laminated. It varies in color from white to dark green and black, and includes many varieties differing in color and composition, as diopside, malacolite, salite, coccolite, augite, etc. They are all silicates of lime and magnesia with sometimes alumina and iron. Pyroxene is an essential constituent of many rocks, especially basic igneous rocks, as basalt, gabbro, etc.☞ The pyroxene group contains pyroxene proper, also the related orthorhombic species, enstatite, bronzite, hypersthene, and various monoclinic and triclinic species, as rhodonite, etc.
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Century Dictionary and Cyclopedia
    • n pyroxene An important mineral species, embracing many varieties differing in appearance and chemical composition. It occurs in monoclinic crystals, often short prismatic in habit, and with an angle in front of nearly 90°, so that these crystals resemble square prisms. Granular forms are common, and also massive varieties, the latter being usually coarsely laminated in structure, rarely fibrous or columnar. The color varies from white to gray, green, brown, and black, and the composition from the simple metasilicate of calcium and magnesium to kinds containing, with calcium or magnesium, or both, iron, manganese, and aluminium. The different varieties are usually divided into two groups, the non-aluminous and the aluminous. Of the former the prominent kinds are — diopside or malacolite, which contains only calcium and magnesium, and is white to gray or light-green in color, with the subvarieties called alalite or mussite (the diopside proper, from the Mussa Alp in the Ala valley in Piedmont, occurring in beautiful slender crystals), traversellite, canaanite, and white granular coccolite, and those containing iron, namely the grayish-green to deep-green or black salite, occurring in laminated masses, the crystallized baikalite, the granular green coccolite, and the deep-green diallage, which is characterized by a distinct parting parallel to the orthopinacoid plane and often by a pearly to metalloidal luster on this surface; also the lime-iron variety, hedenbergite, and the manganesian schefferite. The aluminous kinds include fassaite, which is light- to dark-green in color, and the common augite, which is dark-green to black and contains considerable iron. Augite is characteristic of many eruptive rocks, especially those of a basic character, as diabase, basalt, etc. Diallage is an essential constituent of the gabbros, of norite, etc. Besides the above varieties or subspecies belonging to pyroxene proper, the pyroxene group includes the related species enstatite or bronzite and hypersthene, which are orthorhombic in crystallization (hence called rhombic pyroxenes); also the mono clinic species wollastonite, ægirite and acmite, spodumene, and the triclinic rhodonite and babingtonite. Jadeite probably also belongs here. All these are characterized by the same prismatic angle of 87°. This group is closely related to the analogous amphibole (or hornblende) group, the species of which are characterized by a prismatic angle of 124½°; and several of the kinds under the two groups correspond exactly in composition — for example, diopside to tremolite, etc. A change of pyroxene to hornblende by a process of paramorphism is often observed, especially in certain igneous rocks. See uralite and uralitization.
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Chambers's Twentieth Century Dictionary
    • n Pyroxene pī′rok-sēn an important mineral species, occurring in monoclinic crystals
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Etymology

Webster's Revised Unabridged Dictionary
F. pyroxène, from Gr. fire + a stranger; -- so called because it was supposed to the be a stranger, or of rare occurrence, in igneous rocks,]
Chambers's Twentieth Century Dictionary
Gr. pyr, fire, xenos, a guest.

Usage

In literature:

The rock was of garnet gneiss, traversed by black dykes of pyroxene granulite.
"The Home of the Blizzard" by Douglas Mawson
BRONZITE, a member of the pyroxene group of minerals, belonging with enstatite and hypersthene to the orthorhombic series of the group.
"Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3" by Various
Pyroxene, potash in, 220.
"Manures and the principles of manuring" by Charles Morton Aikman
It is supposed to have formed by the alteration of olivine and pyroxene in the igneous rocks.
"The Economic Aspect of Geology" by C. K. Leith
DIALLAGE, an important mineral of the pyroxene group, distinguished by its thin foliated structure and bronzy lustre.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 3" by Various
The rocks are liparites, dacites, hornblende and pyroxene andesites.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 2" by Various
Serpentine, which may be fibrous or scaly, is a secondary product of olivine and certain pyroxenes.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 4" by Various
It seems therefore that a holocrystalline pyroxene-garnet rock may be one source of the diamond found in blue ground.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 4" by Various
Both Great and Little Ararat consist entirely of volcanic rocks, chiefly andesites and pyroxene andesites, with some obsidian.
"Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 4" by Various
PYROXENIC-PORPHYRY, same as augitic-porphyry, pyroxene being Hauey's name for augite.
"A Manual of Elementary Geology" by Charles Lyell
Enstatite and the other orthorhombic pyroxenes are distinguished from those of the monoclinic series by their optical characters, viz.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 6" by Various
Pyroxene-gneisses are less frequent but occur in many parts of both hemispheres.
"Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 2" by Various
Their essential minerals are pyroxene, plagioclase and garnet: chemically they resemble the gabbros.
"Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3" by Various
They consist essentially of felspar with hornblende (generally of brown colour) and pale pyroxene.
"Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 6" by Various
The lava is black, rich in pyroxene, and strongly attracted by a magnet.
"The Catholic World; Volume I, Issues 1-6" by E. Rameur
The pyroxene is morphic, yellow or green, and is surrounded by formless areas of nepheline.
"Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 3" by Various
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In news:

Obtained by the Chemistry and Mineralogy (CheMin) experiment on NASA's Curiosity rover, these data reveal crystalline feldspar, pyroxenes and olivine mixed with some amorphous (non-crystalline) material.
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In science:

The particles could take the form of micron-sized pyroxene or aluminum oxide dust grains.
Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548
This requirement can be met by micronsized grains of pyroxene, but not of olivine.
Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548
Crystalline pyroxene survives for still longer, a consequence of its lower absorptivity at optical wavelengths and hence cooler temperature.
Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548
For the numerical evaluation in (19), we have used the results of Kimura et al. (2002, their Figure 2) for a spherical pyroxene particle, scaled for the luminosity and mass of our K star.
Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548
Pyroxene grains, each a fraction of a micron in size, are a good candidate for the obscuring grains because of their relatively long lifetimes against sublimation—alumina is also a promising high-temperature mineral to consider.
Possible Disintegrating Short-Period Super-Mercury Orbiting KIC 12557548
Kimura et al. (2002) suggest that the dust observed in the tails of sungrazing comets consists mainly of crystalline silicates and perhaps also of amorphous pyroxene at distances farther than 20 R⊙ .
Are the sungrazing comets the inner source of pickup ions and energetic neutral atoms?
Highcalcium pyroxene as an indicator of igneous differentiation in asteroids and meteorites.
Meteoritical and dynamical constraints on the growth mechanisms and formation times of asteroids and Jupiter
The silicates are a mixture of olivine- and pyroxene-type amorphous dust and for part of the stars also up to about 15% of nearly iron free crystalline forsterite and enstatite is observed to be formed (cf. the review of Molster & Waters 2003).
Evolution of interstellar dust and stardust in the solar neighbourhood
In the model calculation of Ferrarotti & Gail (2006), olivine- and pyroxene-type dust are treated as separate species but their production rates are added for the reasons mentioned above.
Evolution of interstellar dust and stardust in the solar neighbourhood
In a recent attempt to fit the sili cate features of the interstellar extinction curve Min et al. (2007) found that the composition of the ISM silicates is consistent with a Mg-rich mixture of olivine and pyroxene with a bigger contribution from pyroxene than from olivine.
Evolution of interstellar dust and stardust in the solar neighbourhood
An olivine-pyroxene mixture with a contribution of more pyroxene than olivine is therefore chosen for modelling the ISM silicates in the present paper.
Evolution of interstellar dust and stardust in the solar neighbourhood
Let fol be the ( fixed) fraction of the silicate dust that has olivine s toichiometry; the fraction 1 − fol then has pyroxene stoichiometry.
Evolution of interstellar dust and stardust in the solar neighbourhood
They are dominated by ferromagnesian olivine and pyroxene minerals embedded in a Ca-Al-rich glassy mesostasis of close-to-feldspathic composition. Different groups of chondrules are recognized based on their textural and chemical properties (Fig. 3.).
Meteorites and the physico-chemical conditions in the early solar nebula
Fig. 3. Scanning electron micrographs of chondrules and CAIs. A. Porphyritic Olivine type I chondrule. B. Porphyritic Olivine Pyroxene type I chondrule. C. Porphyritic Pyroxene type I chondrule. D . Barred O liv ine type I chondrule. E. Porphy ritic O liv ine type II chondrule. F . Amoeboid Olivine Aggregate. G.
Meteorites and the physico-chemical conditions in the early solar nebula
Porphyritic type I chondrules vary from olivine-rich (PO) to pyroxene-rich (PP) with intermediate members rich in olivine and pyroxene (POP).
Meteorites and the physico-chemical conditions in the early solar nebula
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