coesite


Also found in: Dictionary, Wikipedia.

coesite

[′sē‚zīt]
(mineralogy)
A high-pressure polymorph of SiO2 formed in nature only under unique physical conditions, requiring pressures of more than 20 kilobars (2 gigapascals); usually found in meteor impact craters.
References in periodicals archive ?
The discipline was established -25 years ago after discoveries of high pressure minerals, coesite and diamond, in the rocks of the continental affinities, a place where such minerals are "forbidden"according to main geological concepts.
UHPM rocks consist of the fragments of continental and oceanic crustal rocks and associated mafic-ultramafic intrusions and/or mantle peridotite initially formed at shallow lithosphere, but which subsequently have experienced a recrystallization within or above coesite and diamond stability fields (>2.
Here coesite appears in larger nodules, up to a few millimeters in diameter, with its typical radial cracking.
Not until the discovery, several years later, that the "shock metamorphism" of large-body impacts (and nuclear explosions) can form two separate minerals, stishovite and coesite, and that many suspected impact sites had high concentrations of both, did the hypothesis begin to win converts.
When researchers recently fired single-wavelength beams of X rays and then laser light through two small crystals of coesite trapped in a Venezuelan diamond, the patterns of light scattering from the crystals revealed that the material's atoms are more closely packed than they are at atmospheric pressure.
The distances between atoms in the coesite indicated that the material is currently under a pressure of about 36,000 atm.
The pyrope crystals are rich in interesting inclusions such as coesite (the monoclinic polymorph of quartz which formed at pressures higher than 25 kbar, corresponding to depths of some 100 kin), two species for which this is the type locality (ellenbergerite, and magnesiodumortierite) and also phosphoellenbergerite, bearthite, zircon and monazite-(Ce).
1984) Coesite and pure pyrope in high-grade blueschists of the Western alps: a first record and some consequences.
DF died / fief DH dumdum / humhum DJ dingledangle / jinglejangle DL dowdy / lowly DN dogged / noggen DR dashed / rasher DT dread / treat DW dada / wawa DZ danda / zanza DG danda / ganga DI odd / oii DK deled / kelek DM daytide / Maytime DP daddies / pappies DS coedited / coesites DV dad / vav DY dawned / yawney