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Topic: Enstatite

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In the News (Mon 19 Aug 19)

  Bronzite - LoveToKnow 1911
Enstatite is magnesium metasilicate, MgSiO 3, with the magnesia partly replaced by small amounts (up to about 5%) of ferrous oxide; in the bronzite variety, (Mg,Fe)SiO 3, the ferrous oxide ranges from about 5 to 14%, and with still more iron there is a passage to hypersthene.
Like enstatite, bronzite is a constituent of many basic igneous rocks, such as norites, gabbros, and especially peridotites, and of the serpentines which have been derived from them.
Masses sufficiently large for cutting are found in the norite of the Kupferberg in the Fichtelgebirge, and in the serpentine of Kraubat near Leoben in Styria.
www.1911encyclopedia.org /Bronzite   (383 words)

An enstatite (class EL 4-5) chondrite found in 1997 in the Ténéré du Tafassâsset, a part of central Sahara in the northeast of the Republic of Niger.
Enstatite is found as rockbuilding material in basic and ultrabasic rocks such as gabbro, norite and peridotite.
Enstatite meteorites are the least common type of chondrite (stony meteorites containing submillimeter-sized inclusions called chondrules), accounting for only about 2% of the chondrites that fall to Earth.
www.daviddarling.info /encyclopedia/E/enstatite.html   (558 words)

 Enstatite - Wikipedia, the free encyclopedia
Enstatite and the other orthorhombic pyroxenes are distinguished from those of the monoclinic series by their optical characteristics, such as straight extinction, much weaker double refraction and stronger pleochroism.
Enstatite is white, gray, greenish or brown in color; its hardness is 5 - 6, and its specific gravity is 3.2 - 3.3.
Measurements of the calcium, aluminum, and chromium contents of enstatite in these xenoliths have been crucial in reconstructing the depths from which the xenoliths were plucked by the ascending magmas.
en.wikipedia.org /wiki/Enstatite   (539 words)

 Enstatite - LoveToKnow 1911
It is also a common constituent of meteoric stones, forming with olivine the bulk of the material: here it often forms small spherical masses, or chondrules, with an internal radiated structure.
Enstatite and the other orthorhombic pyroxenes are distinguished from those of the monoclinic series by their optical characters, viz.
Enstatite is white, greenish or brown in colour; its hardness is 51, and sp.
www.1911encyclopedia.org /Enstatite   (253 words)

 ENSTATITE (Magnesium Silicate)
Enstatite is a relatively common mineral and is found in metamorphic and some igneous rocks as well as in stony and iron meteorites.
In this case, the elements are iron and magnesium and enstatite is the magnesium end member of the series.
Enstatite is an orthopyroxene or a pyroxene with an orthorhombic symmetry.
mineral.galleries.com /minerals/silicate/enstatit/enstatit.htm   (477 words)

 PSR Discoveries:Hot Idea: Enstatite Meteorites
Enstatite is the magnesium-rich version of a group of minerals called pyroxenes.
The enstatite meteorites include chondrites (many of which have been melted by impacts), aubrites (igneous rocks), stony-iron meteorites, and iron meteorites.
One of the exotic sulfide minerals in enstatite chondrites and aubrites is oldhamite, calcium sulfide (CaS).
www.psrd.hawaii.edu /Dec99/indarch.html   (2183 words)

 [No title]
Enstatite (E) chondrites are a rare and unusual type of meteorite.
E chondrites are unusual in that they are high in the mineral enstatite and most of their iron is in the form of metal or sulfide rather than taken up as oxides in silicates.
This implies that E chondrites formed in an area of the solar nebula that was very poor in oxygen, possibly inside the orbit of Mercury.
www.meteorlab.com /METEORLAB2001dev/enstchon.htm   (146 words)

 Astrology & Gemstones, Birthstones: Enstatite Gemstone - Gems shop online
The name 'Enstatite' comes from the Greek "Enstates" which means "An Opponent" referring to its refractory nature.It is composed of Magnesium Silicate.
The most famous variety of Enstatite is Chrome-Enstatite, the emerald-green variety which is commonly cut as a gemstone.
Enstatite is a relatively common mineral and is found in metamorphic and some igneous rocks as well as in stony and iron meteorites.Enstatite is an orthopyroxene or a pyroxene with an orthorhombic symmetry.
www.findyourfate.com /gemology/gemstones/Enstatite.html   (167 words)

 Thaigem.com | Info Center | Gemstone Discovery | Enstatite
Enstatite occur in association with volcanic rocks and meteorites.
Enstatite is commonly collected as mineral specimen rather than cut into gemstones.
With a hardness of 5.5 Enstatite is considered a rather soft stone.
www.thaigem.com /dis_enstatite.asp   (268 words)

 Faceted Enstatite from Morogoro, Tanzania   (Site not responding. Last check: 2007-11-02)
Enstatite, a collector's gem, is a magnesium silicate of Mohs' hardness 5.5.
Faceting enstatite is a rather tricky endeavor because of the mineral's tendency to cleave when ground in certain directions.
In the hands of a very skillful metalsmith, this gem could be set in a pendant (Enstatite is too fragile for use in a ring).
www.mtlilygems.com /enstatite/ens645.html   (107 words)

 Enstatite / EH3 / Sahara 97096, 97072, 97158   (Site not responding. Last check: 2007-11-02)
It can be classified among the most primitive enstatite chondrite comparable to Qingzhen and Parsa.
The main mass SAH97091, EH3 is a single stone found in 1997, weighing 6140g.
Note the engraved name "Sahara 97096" on one side of the slice, this was made on the past by our family to prevent some mixt on the different paired
www.meteorites.tv /contents/en-us/d36.html   (211 words)

 Multicolour.com > Gem Library > Gemstones Varieties > Enstatite   (Site not responding. Last check: 2007-11-02)
Enstatite is a member of the pyroxene group of minerals.
Because of its two directions of prismatic cleavage, enstatite is rather difficult to facet.
A dark brown six-rayed star enstatite is known to occur in Mysore, India.
www.multicolour.com /gemstones/enstatite.html   (312 words)

 Bronzite - Wikipedia, the free encyclopedia
Rather than a distinct species, it is really a ferriferous variety of enstatite, which owing to partial alteration has acquired a bronze-like sub-metallic luster on the cleavage surfaces.
Masses sufficiently large for cutting are found in the norite of the Kupferbergin the Fichtelgebirge, and in the serpentine of Kraubat near Leoben in Styria.
In this connection mention may be made of an altered form of enstatite or bronzite known as bastite or schiller spar.
en.wikipedia.org /wiki/Bronzite   (429 words)

 www.meteorites.com classification
Within each of these groups, chondrites are also classified according to their petrologic type; that is, on the basis of the degree of alteration (or alteration grade) to which they have been subjected on their parent body prior to arriving on Earth.
Enstatite chondrites (or E chondrites) represent only 1.0% of all falls.
They are sometimes referred to as enstatite achondrites and might somehow be related to the enstatite chondrites.
www.meteorites.com /classif.html   (3318 words)

 Enstatite: Enstatite mineral information and data.
Arima, M. and Onuma, K. (1977) The solubility of alumina in enstatite and the phase equilibria in the join MgSiO3-MgAl2SiO6 at 10-25 kbar.
Ohashi, Y. (1984) Polysynthetically-twinned structures of enstatite and wollastonite.
Duffy, T.S. and Vaughan, M.T. (1988) Elasticity of enstatite and its relationship to crystal structure.
www.mindat.org /min-1384.html   (685 words)

 Enstatite Achondrites
Description and classification (T. Bunch and J. Wittke, NAU): The meteorite has an igneous texture; it is a brecciated enstatite orthopyroxenite with a series of prominent, parallel compression fractures (0.1 to 0.8 mm spacing)
None of the exotic sulfides common to aubrites and enstatite chondrites were found.
Shock level, S4 (parallel fractures, reduced birefringence, and mottled extinction in enstatite; all plagioclase is maskelynite); weathering grade is W2/3.
www4.nau.edu /meteorite/Meteorite/EnstatiteAchond.html   (182 words)

 New analysis sheds light on Earth's origins
ANN ARBOR---A new analytical method has resolved a longstanding scientific debate on the origins of Earth and the moon, researchers from the University of Michigan and the Swiss Federal Institute of Technology report in the June 2 issue of Science.
Because the ratio of different forms (isotopes) of oxygen in materials from Earth and the moon matches that of enstatite chondrites---but no other meteorites---it had been proposed that Earth formed from materials much like the enstatite chondrites.
Based on this evidence, "we propose for the first time with much certainty that there is no direct genetic relationship between Earth and enstatite chrondrites." Instead, the data support the alternative idea that planets, as they formed, received materials from very broad regions of the solar system.
www.eurekalert.org /pub_releases/2000-05/UoM-Nasl-3005100.php   (271 words)

 Molecular dynamics simulations of MgSiO3 enstatite and seismic discontinuity in the upper mantle
The seismic velocities for three kinds of enstatite (low clinoenstatite, L-CEn; orthoenstatite, OEn; and high-pressure clinoenstatite, HP-CEn), which is a major component in the upper mantle, were estimated using molecular dynamics simulations based on the interatomic potential model.
We conclude that the transitions in enstatites are related to the seismic discontinuity observed at depths less than 410 km and that enstatite is as an important a mineral as olivine for the mineralogical model and for the anisotropic propagation of seismic waves in the Earth's upper mantle.
enstatite and seismic discontinuity in the upper mantle, Geophys.
www.agu.org /pubs/crossref/2005/2004GL022264.shtml   (270 words)

The mineralogy of Shallowater is inconsistent with an origin from either of the enstatite chondrite parent bodies (EH and EL), or from the aubrite parent body, and is considered to represent a fourth enstatite parent body.
The first stage reflects rapid cooling (supercooling) from a melt temperature of ~1580°C to ~712°C. This is consistent with the collisional breakup of a differentiated body, which consisted primarily of an enstatite melt phase, as a result of an impact with a solid enstatite-like object.
This was a low-velocity collision that permitted the gravitational reassembly of the disrupted body and the incorporation of xenolithic material from the solid body.
www.meteoritestudies.com /protected_SHALLOW.HTM   (872 words)

 Enstatite, Gemstones, Colored Gems, Semi Precious Gems, Gem Cutting, Faceting
Enstatite, greenish brown, 0.62ct., oval, VSI, 4.7x6.8mm, Asia.
Enstatite, light yellow, 1.06ct., pulsar emerald, VSI, ~5.5x6.5mm, E. Africa.
Enstatite, pale yellow, 1.06ct., pulsar, VSI, ~5x6mm, unknown locality.
www.buenavistagemworks.com /gemstones/gempages/enstatite.htm   (302 words)

 Ocean 540: Petrological Relationships in Generating Ocean Crust
The naturally occurring diopside is of the composition marked a and the enstatite is of the composition marked b.
The diopside rich member is in the monoclinic crystal system while the enstatite rich member is in the orthorhombic crystal system, thus they are often referred to as clinopyroxene (cpx) and orthopyroxene (opx), respectively.
The melt is generated mainly at the expense of diopside but also minor amounts of forsterite; additional enstatite is produced.
www2.ocean.washington.edu /oc540/lec02-7   (888 words)

Figure 5.12: Laboratory spectra of enstatites; the x-axis is wavelength in µm, the y-axis is the normalised extinction K.
The three amorphous enstatite spectra are almost identical.
The three crystalline enstatite spectra have peaks in the same positions, but there are variations in the exact shapes of the features.
www.missouri.edu /~speckan/witch-stuff/Research/chapter5/node5.html   (686 words)

 Astron. Astrophys. 363, 1115-1122 (2000)
In the pure enstatite group, the spectra are not so much dependent on the type of crystal structures (ortho or clino) in the mid infrared region, but the peaks of the clinoenstatite in the mid infrared region become about 30% stronger than those of the orthoenstatite.
The enstatite group shows sharp peaks compared with the orthopyroxenes, which has slightly broader or degenerate bands.
The mass extinction coefficients of the amorphous pyroxenes; diopside glass, enstatite gel, and enstatite glass, which are multiplied by 1, 10, and
aa.springer.de /papers/0363003/2301115/sc3.htm   (616 words)

 ENSTATITE - Online Information article about ENSTATITE
long before enstatite, which was first described by G.
Kenngott in 1855, and named from ivgTaTi S, " an opponent," because the mineral is almost in-fusible before the See also:
Enstatite and the other orthorhombic pyroxenes are distinguished from those of the See also:
encyclopedia.jrank.org /EMS_EUD/ENSTATITE.html   (443 words)

Enstatite is one of the pyroxene family - a series of magnesium to iron rich silicates.
Cuttable enstatite varies in color from a gray to yellowish green or olive green, to an iron rich brownish green.
Brownish green enstatite is found in Myanmar, Norway and the U.S.A. (California).
www.gemsandjewelryrus.com /ensatite.html   (105 words)

 Condensation sequences - expected minerals
Amorphous enstatite has a single peak at about 9.4 µm.
As the forsterite is transformed into enstatite we should see a shift in the main spectral feature from about 9.8 µm to about 9.4 µm, as well as shifts in the minor peaks (see Fig.
If the density structure of the stellar atmosphere is such that there is a high density region at a sufficient distance from the star for it to be cool enough for the enstatite to react with gaseous iron, various ferro-magnesian olivines should form (Tielens 1990).
www.missouri.edu /~speckan/witch-stuff/Research/chapter5/node7.html   (949 words)

 enstatite chondrite concept from the Meteorites knowledge base
enstatite chondrite concept from the Meteorites knowledge base
rock > meteorite > highly reduced meteorite > enstatite chondrite
Next anhydrous chondrite: ordinary chondrite Up: anhydrous chondrite, highly reduced meteorite Previous anhydrous chondrite: CK chondrite
www.site.uottawa.ca:4321 /meteorites/enstatitechondrite.html   (465 words)

 EarthRef.org Reference Database (ERR) -- Zhang et al. 1995
We have carried out instrumental neutron activation analyses of 11 enstatite chondrites and electron microprobe analyses of 17 enstatite chondrites, most of which were previously little described.
Most of the petrologic type criteria are not applicable to enstatite chondrites and, unlike the ordinary chondrites, texture and mineralogy reflect different aspects of the meteorite history.
We therefore propose that the existing petroloic type scheme not be used for enstatite chondrites.
earthref.org /cgi-bin/err.cgi?n=60604   (285 words)

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