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Primitive enstatite achondrites

Pilski A. S., Przylibski T. A., Łuszczek K.

Meteorites

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2011

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Vol. 0, No. 0

9-21

EN

Conclusions drawn from the breadth of analytical data on primitive achondrites and enstatite chondrites paired with results of research performed by the authors have led the authors to propose the establishing of a new group of meteorites: primitive enstatite achondrites. The group is defined as the residual remaining after the partial melting of their protolith, which, in the case of primitive enstatite achondrites, is the parent body of enstatite chondrites. In this article are characterized textural features and characteristics of their mineral, chemical, and isotopic composition. The most important of these defining features are the presence of relic chondrules and/or triple junctions of crystal faces, as well as characteristic atomic and molar ratios of main elements: Si, Al, Fe, Mg, Mn and Ca, and particularly the molar ratios Fe/Mn and Fe/Mg. Another important characteristic is the isotopic composition of entrained noble gases, especially ratios of the heaviest of the isotopes and oxygen isotopes, whose values should be close to that typical for enstatite chondrites. It seems likely that the first meteorite to be classified as primitive enstatite achondrite will be the Zakłodzie enstatite achondrite.

2

Diamonds in ureilites

Jakubowski T., Karczemska A., Kozanecki M.

Meteorites

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2011

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Vol. 0, No. 0

3-8

EN

The presence of diamonds in meteorites was confirmed for the first time in the Novo-Ureiureilite in 1888. Ureilites are a rare class of achondrites, often referred to as primitive achondrites. They are composed of olivine and pyroxene (pygeonite), as well as graphite inclusions often coexisting with diamonds. The following three main hypotheses of diamond origin in ureilites have been proposed: the HPHT process, graphite-to-diamond conversion under shock compression due to impact on the parent body (the most popular theory, as of the time of publication), and the CVD process in the solar nebula. The samples of all types of ureilites, from less shocked up to highly shocked, were examined using Raman Spectroscopy and Scanning Electron Microscopy. The results show the presence of diamonds in all of our samples. Of particular significance is the comparison of Raman spectra of diamonds and graphite phases of different ureilites.

3

Microscopic investigations of Shisr 007 meteorite

Szurgot M., Polański K., Burski M.

Scientific Bulletin. Physics / Lodz University of Technology

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2009

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Vol. 30

73-83

EN

Elemental composition, mineral composition and microstructure of Shisr 007 meteorite found in 2001 have been studied by analytical electron microscopy. It was established that the main meteorite minerals: olivines, pyroxenes, troilite, and graphite identified in the sample represent extraterrestrial minerals typical of olivine-pyroxene achondrites. Chemical and mineral composition, and texture confirm previous classification of this achondrite as ureilite.

PL

Badano skład pierwiastkowy, skład mineralny i mikrostrukturę meteorytu pustynnego Shisr 007 wykrytego w Omanie w 2001 roku. Do badań wykorzystywano analityczną mikroskopię elektronową. Ustalono, że zarówno skład pierwiastkowy, jak i skład mineralny, a także mikrostruktura tego nowego materiału pozaziemskiego potwierdzają jego przynależność do urelitów. Stwierdzono, że zawartość fajalitu w pewnych oliwinach jest wyższa, a zawartość wollastonitu w pewnych piroksenach jest wyższa lub niższa niż poprzednio ustalono. Ureilit Shisr 007 uległ prawdopodobnie utlenieniu podczas wietrzenia na Ziemi.

4

Different diamonds in meteorites - DaG 868 and NWA 3140 ureilites

Karczemska A., Jakubowski T., Vergas F.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

292-297

EN

Purpose: Ureilites are a rare type of meteorites containing tiny diamond grains. In our research we used two ureilites: NWA 3140 and DaG 868. The aim of this paper is to show the non-uniformity of carbon in ureilites, especially differences of ureilitic diamonds. Design/methodology/approach: One of the best methods to examine different allotropic forms of carbon is Raman Spectroscopy. This method used to investigate diamonds provides a lot of information about diamond polytypes, crystals sizes, a level of defects and internal stresses, etc. 2D imaging was done with a Confocal Raman Imaging alpha 300 R WITec apparatus equipped with an Nd:YAG laser with 532 nm excitation. The spectra were collected with a high-sensitive confocal microscope connected to a high-throughput spectrometer equipped with a CCD camera. Mean and local elemental compositions of the samples were determined by an energy dispersive X-ray (EDX) method. A scanning electron microscope HITACHI S-3000 N was used to characterize microstructures (carbon veins) of the samples. Findings: Different diamond generations were found in ureilites in the presented research with a wide range of Raman shifts from 1309 cm -1 to 1339 cm -1. Also graphite and amorphous carbon were found. Research limitations/implications: Presented research is another step to solve the problem about diamond origin in meteorites. Practical implications: Understending diamonds and the other carbon phases in meteortites could help in manufacturing new carbon materials in laboratory. Originality/value: Authors use Raman imaging to show distribution of diamonds in ureilites, this is pioneer research, results of DaG 868 and NWA 3140 are shown for the first time.