摘要
通过详细研究世界范围内1842—1993年他人76个及作者42个含Cr的且与白云母同结构的云母化学成分资料,确立了自然产出的云母族矿物结构层内八面体中Cr^(3+)与Al^(3+)的完全类质同象关系。重新核查了云母族矿物分类,强调了按云母族矿物结构层内,八面体位置上所占据的阳离子类型,及其类质同象程度进行亚族划分的原则,将过去的二八面体型Al系列即白云母亚族。
Generally the mica group can be classified on the basis of their octahedral occupancy into the trioctahedral subgroup corresponding to the Mg-Fe series and the dioctahedral subgroup corresponding to the Al series considered before.In fact, many of the major rock-forming silicate minerals appear to be capable of accommodating substantial substitutional Cr3+ in their crystal structure, while the maximum extent of the substitution of Cr3+ for Al3+in octahedral positions in naturally occurring micas is far greater, especially at low pressures, than people imagine hitherto. Data of 118 chromian muscovites from different corners of the world including data of 42 Chinese samples analyzed by the authors have been gathered and on that basis the relationship between Cr3+ and Al3+ at octahedral sites has been established, which shows that there is an extensive solid-solution series between octahedral Cr3+ and Al3+ , which was rarely demonstrated before.In regard to the existence of a complete Mg-Fe solid-solution series in the mica group, this paper for the first time proposes the existence of a Cr-Al series in the mica group, and accordingly extends the muscovite subgroup, into a new subgroup——the Cr-Al mica subgroup.
出处
《地质论评》
CAS
CSCD
北大核心
1995年第3期272-276,共5页
Geological Review
关键词
铬铝云母亚族
云母族
白云母
isomorphous replacement of the Cr-Al series, Cr-Al mica subgroup, mica group
