High resolution electron microscopic characterization of phyllosilicates and finding of a new type with 11Å structure in Yamato-74662

• Main Author: Akai, Junji
• Language: English
• Published: 1982
• Subjects: Yamato; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/record/1384/files/KJ00000012018.pdf; https://nipr.repo.nii.ac.jp/records/1384

P(論文) Matrix materials in Yamato-74662 have been examined by HREM and AEM. Under microscopic observations, phyllosilicates in Yamato-74662 were found; i) as matrix materials, ii) in irregular cavities, and iii) replacing pyroxene and olivine grains. Five types of phyllosilicates in the matrix were observed by HREM; a) 7Å platy phyllosilicate, b) 7Å poorly organized tubular phyllosilicate, c) 17Å platy phyllosilicate, d) poorly organized 7Å layer structures with interlayering of 5Å layer structure and e) 11Å platy phyllosilicate. Parallel intergrowth of the 11Å mineral and 7Å berthierine, and characteristic HREM suggest that the 11Å mineral is a new phyllosilicate with an interstratified structure of serpentine-like and brucite-like layers. Mineralogy and texture of the matrix suggest that the phyllosilicates were derived by alteration from such precursor materials as CV chondrites, and experienced some mixing or brecciation process after (or during) alteration. departmental bulletin paper