Computer Science
Scientific paper
Jul 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994metic..29..538t&link_type=abstract
Meteoritics (ISSN 0026-1114), vol. 29, no. 4, p. 538-539
Computer Science
Chemical Composition, Crystal Structure, Meteoritic Microstructures, Chemical Bonds, Temperature Effects, X Ray Diffraction
Scientific paper
Crystal structures of plagioclases from three monomict eucrites, ALH 85001 (ALH), Moore County (MC), and Serra de Mage (SM), were refined using X-ray diffraction data. The chemical compositions of plagioclases selected from the eucrites were An(92-94), An93, and An90 for the plagioclase of ALH, SM, and MC respectively according to the results of the microprobe analysis. The X-ray diffraction photographs indicated that b reflections are sharp and fairly strong in all three eucrites together with sharp and strong a reflections. C reflections are, however, weak and very diffuse in ALH, strong and fairly sharp in SM, and medium and diffuse in MC. Totals of 4237 reflections (a,b) for ALH, 6637 reflections (a,b,c) for Sm, and 6884 reflections (a,b,c) for MC were collected and supplied to the structure refinements. The average bond lengths of tetrahedral cations are shown together with those in the Pasmeda anorthite, where Al and Si are perfectly ordered. From those results, it can be concluded that the Al/Si ordering was attained in the tetrahedral sites approximately 94%, approximately 92%, and approximately 77% in MC, SM, and ALH respectively. The intensity distribution of b reflections depends on the ordering of Al/Si in the tetrahedral sites and it is sensitive to the cooling rate in the temperature range of 900-1200 C, where the cooling rate of MC may be comparable with that of SM. The cooling of MC and SM is much slower than that of ALH in 900-1200 C. The diffraction characteristics in c reflections, which are sensitive to the cooling rate in the range of 800-300 C, indicate that SM experienced the extremely slow cooling in that temperature range and that the cooling of MC is much slower than that of ALH.
Hoshi Takeo
Tagai Tokuhei
Takeda Hidenori
No associations
LandOfFree
Crystal structures and diffraction characteristics of the calcic plagioclases from three monomict eicrites: ALH 85001, Serra de Mage, and Moore county does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Crystal structures and diffraction characteristics of the calcic plagioclases from three monomict eicrites: ALH 85001, Serra de Mage, and Moore county, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crystal structures and diffraction characteristics of the calcic plagioclases from three monomict eicrites: ALH 85001, Serra de Mage, and Moore county will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-822041