钙质闪石11种阳离子占位度的X射线衍射测定  

X-RAY DIFFRACTION DETERMINATION OF 11 CATION SITE-OCCUPANCIES IN CA-AMPHIBOLE

作　　者：孙以谏[1] 刘万余[1] 黄俊杰[1] 王冠鑫[2] 张建洪[3] 

机构地区：[1]南京地质矿产研究所,南京210016 [2]中科院广州地球化学研究所,广州510640 [3]中国地质大学,北京100083

出　　处：《火山地质与矿产》1998年第3期177-195,共19页Volcanology & Mineral Resources

基　　金：国家自然科学基金!49413179

摘　　要：本义对前期[1][2]的理论分析成果进行修改和验证。前期曾用大量文献上的晶体结构参数仅演为理论的X射线树木图，从中选出若干条特征峰，用逐步回归方法对其强度比与钙质闪石的11种阳离子占位度问，建立一系列经验公式，用以估算未知的钙质冈石样品阳离子占位度，精度在85％－98％之间，多数阳离子精度超过90％．在闪石晶体化学研究上具有重要意义的阳离子如M1、M3位中Mg、Fe2＋、A位的K、三缺值Em及万位的Si等精度均超过90％；晶体化学类型定名的准确度达85％。成果表明，利用X射线衍射法估算闪石的阳离子占位在理论上是可能的。但还有待于用实测数据检验其可行性。本次工作的日的，便是以实测数据来验证前期理论成果并确定其可靠性。通过反复改变衍射圈上特征反射的选择和改变样本数，以实测结果验证各种组合建立的线性模型，所估算的各品位各种阳离子占位数的准确度在78％－96％之间，大多数大于80％，接近或超过90％的有八位的K、空缺值Em、位的Mg、Fe没＋及T位的Si等。晶体化学类型定名的准确度可达80％。但在建立线性模型时，必须将理沦计算的粉末国与实测阁一起进行统计。所选用的实测样品愈多，该族矿物种后愈广泛，则建立的模型的代表性也愈广泛，可靠程度愈高。The present paper modifies and tests the previous resea-rch results of theoretical anlyses. Inthe previous study, certain characteristic peaks were selected from the theoretical X - raydiffraction powder patterns given by crystal structure parameter version in many references. Bythe method of step by step regression a series of experimental formulas were given between intensities and cation site- occupancies of 11 ca - amphiboles to calculate the cation site - occupancy of unknown ca - amphibole with the precision of 85 % - 98 %, but most cation precisionsurpasses 9o%. Based on the experiment that the cation precision is more than 9o %, such asMg.Fe2+ in M1. M3 sites. K in A site, vacancy Em and Si in Ti site, which have important significience in crystal chemistry study on amphibole, the results show it is possible to calculatecation occupancy for amphibole by x - ray diffraction in theory but it required proof - test itsfeasibility by experiments.The purpose of this study is to prove the previous results and determinate its reliability,through repeatedly changing samples and selection of character reflection in an X - ray diffraction pattern, identified results test combined linear models. The results show that the precisionof estimated each crystal site and cation site - occupancy rangs from 78 % - 96 %, most of themmore than 80 %, K in A site is near or more than 90 %, as well as vacancy Em, Mg.Fe2 + in ∑site and Si in T site. The precision is up to 80% for named crystal chemistry class but to establish linear model both theoretical calculation powder pattern and identification pattern should beput together. The more measured sample selected, the wider the mineral classes, the morewidespreed the representative model, the higher reliabilty is. The study results prove that estimation of cation occupancy for unknown sampie by the method of linear model is correct, Themethod is turned out not only possible but filrther more feasible.

关 键 词：钙质闪石 阳离子占位 X射线衍射 矿物分析 

分 类 号：P578.955[天文地球—矿物学] P575.5[天文地球—地质学]