| 大别山绿辉石晶体结构的再研究—兼与谢窦克等同志商榷 |
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| 引用本文： | 郭卫东,罗谷风.大别山绿辉石晶体结构的再研究—兼与谢窦克等同志商榷[J].地质论评,1995,41(4):311-319. |
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| 作者姓名： | 郭卫东 罗谷风 |
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| 作者单位： | 南京大学地球科学系
(郭卫东，罗谷风)，南京大学地球科学系(郭昀) |
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| 基金项目： | 国家自然科学基金 (编号49070082) |
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| 摘 要： | 谢窦克等曾测定了大别山一个绿辉石的晶体结构，认为它具Ｐ２／ｃ空间群；四面体链分别呈ＳＡ和ＯＢ扭转；Ｍ阳离子日位全部为６次配位的八面体：Ａｌ在所有这四种晶位另均有相当多的占有率，为绿辉石的新型结构。本文对该资料再研究后确认其真实空间群为Ｐ２／ｎ；结构中仅有一种Ｏ旋转的四面体链；Ｍ２和Ｍ２晶位为８次配位；Ａｌ全部进入Ｍ１（１）晶位，Ａｌ－Ｍｇ呈完全有序分布，属典型的Ｐ２／ｎ有序绿辉石。本文给出了重新计
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| 关 键 词： | 绿辉石 空间群 晶体结构 大别山 |
RESTUDY ON THE CRYSTAL STRUCTURE OF OMPHACITE FROM THE DABIE MOUNTAINS |
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| Guo Weidong,Luo Gufeng and Guo Yun.RESTUDY ON THE CRYSTAL STRUCTURE OF OMPHACITE FROM THE DABIE MOUNTAINS[J].Geological Review,1995,41(4):311-319. |
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| Authors: | Guo Weidong Luo Gufeng and Guo Yun |
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| Abstract: | Xie Douke et al. (1989) determinated the crystal structure of omphacite from the Dabie Mountains. They affirmed that this crystal has space group P2/c, and in its structure, there are two kinds of tetrahedral chain with S-rotation and O-rotation respectively; the four symmetrically unequivalent M-sites are all 6-coordinated octahedra and Al exists in all of them with higher occupancies.A restudy on the data of this structure was carried out by the authors. It reveals that the true space group of the omphacite from the Dabie Mountains is P2/n rather than P2/c; and in its structure, there is only one kind of tetrahedral chain with O-rotation, the O3-O3-O3 chain angle is 170. 02% andM2 and M2(1) sites are of 8-coordination distinguished from 6-one of Ml and M1 (1) sites. In addition, the authors deem that, based on the M-O bond separation, all of Al should enter the smallest M1(1) site, while the site occupation between Al and Mg would be completely ordered. Thus, the structure mentioned above is a typical one of ordered omphacite with space group P2/n, rather than a new type P2/c structure for omphacite.The cause responsible for an incorrect space group is that the selection of the unit cell does not conform to the standard. The authors, therefore, recalculated the unit cell parameters and atom coordinates based on the data given by Xie Douke et al. , and furnish the correct ones here. Although some major errors have been found in the structural explanation given by Xie Douke et al. , the structural data are valuable. |
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| Keywords: | omphacite space group crystal structure Dabie Mountains |
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