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A new nondestructive X-ray method for the determination of the 3D mineralogy at the m scale
- Source :
- American Mineralogist, American Mineralogist, Mineralogical Society of America, 2004, 89, pp.547, The American Mineralogist, The American Mineralogist, 2004, 89, pp.547
- Publication Year :
- 2004
- Publisher :
- HAL CCSD, 2004.
-
Abstract
- The combination of synchrotron-based X-ray absorption and fluorescence computed tomographies (CT) is a new method allowing a noninvasive and nondestructive determination of the three-dimensional (3D) mineralogy with micrometer resolution of sub-millimeter silicate grains, possibly stored in a silica holder. These CT were performed with beams of a few tens of keV from a third-generation synchrotron source on one olivine grain of the NWA817 Martian meteorite presenting a reddish alteration phase. The reconstructed sections show a network of fractures and a few micrometer-thick layers formed on one grain. The 3D facet orientation and the X-ray attenuation coefficient indicate that this grain is an Fo44±9 olivine crystal. The fluorescence section reveals rims enriched in Fe (a major element) or depleted in Ca (a minor element). This CT combination shows that the micrometer-thick layer is preferentially formed on the (010) olivine face and has a lower density (3.5 ± 0.4 g/cm3 ) than the olivine, even though it is enriched in Fe. Its complex nano-petrography and the distributions of nanometer-sized voids and fractures in such a micrometer thick layer, first observed by scanning electron microscopy on focused ion-beam cuts, is not shown by CT. The precision presently achieved, although moderate, is sufficient to obtain a 3D semi-quantitative view of the mineralogy consistent with the one previously established by electron probe microanalyses (Sautter et al. 2002).
Details
- Language :
- English
- ISSN :
- 0003004X and 19453027
- Database :
- OpenAIRE
- Journal :
- American Mineralogist, American Mineralogist, Mineralogical Society of America, 2004, 89, pp.547, The American Mineralogist, The American Mineralogist, 2004, 89, pp.547
- Accession number :
- edsair.dedup.wf.001..f67a4f42cacf6b1e7fedb3e2819bdbd5