Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite
P(論文) X-ray single crystal diffraction studies, supplemented by electron microprobe analyses, have been made of pyroxene and chromite in the Yamato (b) achondrite. The major phases in the meteorite are homogeneous grains of bronzite (Ca_2Mg_<74>Fe_<24>) with no exsolution lamellae of aug...
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ftnipr:oai:nipr.repo.nii.ac.jp:00000832 2024-09-09T19:51:59+00:00 Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite Takeda, Hiroshi Reid, Arch M. Yamanaka, Takamitsu 1975-08 application/pdf https://nipr.repo.nii.ac.jp/record/832/files/KJ00000011806.pdf eng eng Memoirs of National Institute of Polar Research. Special issue 5 83 90 AA00733561 https://nipr.repo.nii.ac.jp/record/832/files/KJ00000011806.pdf 1975 ftnipr 2024-06-17T04:03:38Z P(論文) X-ray single crystal diffraction studies, supplemented by electron microprobe analyses, have been made of pyroxene and chromite in the Yamato (b) achondrite. The major phases in the meteorite are homogeneous grains of bronzite (Ca_2Mg_<74>Fe_<24>) with no exsolution lamellae of augite, and euhedral to subhedral grains of chromite with high Cr and Mg contents. Troilite and metallic iron are also present. The pyroxene is identical in composition to those of the hypersthene achondrites but the portion of the meteorite examined does not have the very coarse-grained and brecciated texture of most hypersthene achondrites. X-ray diffraction study of an octahedral chromite grain shows that it consists of portions with slightly different orientations. Measurement of the magnetic moment of the chromite shows no abrupt change in magnetization and the absence of a distinct thermal hysteresis between 20 and 400℃, consistent with the magnetic properties of chromite. Yamato (b) is a unique hypersthene achondrite with a non-brecciated granoblastic texture. We suggest that Yamato (b) may have undergone a reheating event that caused recrystallization of the pyroxene, without change in composition. departmental bulletin paper Other/Unknown Material Memoirs of National Institute of Polar Research Polar Research National Institute of Polar Research Repository, Japan Yamato ENVELOPE(35.583,35.583,-71.417,-71.417) |
institution |
Open Polar |
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National Institute of Polar Research Repository, Japan |
op_collection_id |
ftnipr |
language |
English |
description |
P(論文) X-ray single crystal diffraction studies, supplemented by electron microprobe analyses, have been made of pyroxene and chromite in the Yamato (b) achondrite. The major phases in the meteorite are homogeneous grains of bronzite (Ca_2Mg_<74>Fe_<24>) with no exsolution lamellae of augite, and euhedral to subhedral grains of chromite with high Cr and Mg contents. Troilite and metallic iron are also present. The pyroxene is identical in composition to those of the hypersthene achondrites but the portion of the meteorite examined does not have the very coarse-grained and brecciated texture of most hypersthene achondrites. X-ray diffraction study of an octahedral chromite grain shows that it consists of portions with slightly different orientations. Measurement of the magnetic moment of the chromite shows no abrupt change in magnetization and the absence of a distinct thermal hysteresis between 20 and 400℃, consistent with the magnetic properties of chromite. Yamato (b) is a unique hypersthene achondrite with a non-brecciated granoblastic texture. We suggest that Yamato (b) may have undergone a reheating event that caused recrystallization of the pyroxene, without change in composition. departmental bulletin paper |
author |
Takeda, Hiroshi Reid, Arch M. Yamanaka, Takamitsu |
spellingShingle |
Takeda, Hiroshi Reid, Arch M. Yamanaka, Takamitsu Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite |
author_facet |
Takeda, Hiroshi Reid, Arch M. Yamanaka, Takamitsu |
author_sort |
Takeda, Hiroshi |
title |
Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite |
title_short |
Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite |
title_full |
Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite |
title_fullStr |
Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite |
title_full_unstemmed |
Crystallographic and Chemical Studies of a Bronzite and Chromite in the Yamato (b) Achondrite |
title_sort |
crystallographic and chemical studies of a bronzite and chromite in the yamato (b) achondrite |
publishDate |
1975 |
url |
https://nipr.repo.nii.ac.jp/record/832/files/KJ00000011806.pdf |
long_lat |
ENVELOPE(35.583,35.583,-71.417,-71.417) |
geographic |
Yamato |
geographic_facet |
Yamato |
genre |
Memoirs of National Institute of Polar Research Polar Research |
genre_facet |
Memoirs of National Institute of Polar Research Polar Research |
op_relation |
Memoirs of National Institute of Polar Research. Special issue 5 83 90 AA00733561 https://nipr.repo.nii.ac.jp/record/832/files/KJ00000011806.pdf |
_version_ |
1809921344919306240 |