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三个干燥加热斜长石的分析晶格参数表明,它们具有像合成斜长石那样“高”的有序度。它们的晶体结构分析证明,在过渡成分的高温斜长石中,具有一种意想不到的 Al、Si 有序度(Kroll 1978)。特别是 An27.8(于1160℃加热22天),在 T_1O 四面体位置有 t_1o—0.4Al,其它三个位置各自具有 t_1o—0.3Al[即〈t_1m〉=1/3(t_1m+t_2O+t_2m)—0.3Al。An52(于1255℃加热29天),具有 t_1o—0.48.Al,〈t_1m〉—0.35Al。An68.7(于1365℃加热42天),具有 t_1o—0.52Al,〈t_1m〉—0.39Al。这些数据需要用测量斜长石中 Al,Si 分配的图解,根据人们熟知的△131=20(131)—20(1 )参数以及晶格角γ进行估算。用△131和γ作为钙长石分子百分比的函数作图,并绘制 t_1o—〈t_1m〉图。用γ绘制的图可得到比较精确的结果,如果斜长石中正长石含量尚不知道的话,应使用这种图,但是晶格参数必须慎重地精选.△131值的测定是要容易得多,利用它确定结构状态的精确度却稍许差一些,但是要求正长石的含量必须是已知的.此外,如果不同样品的 t_1o—〈t_1m〉值对比较是富有意义的,还要求必须修正钙长石含量对△131的影响.
The analytical lattice parameters of the three dry, heated plagioclase show that they have a “high” degree of order as synthetic plagioclase. Their crystal structure analysis shows that there is an unexpected degree of Al, Si ordering in the high-temperature plagioclase of transitional components (Kroll 1978). Especially An27.8 (heated at 1160 ° C for 22 days), with t_1o-0.4Al at the T_1O tetrahedron and t_1o-0.3Al at each of the other three positions (ie = 1/3 (t_1m + t_2O + t_2m ) -0.3Al. An52 (heated at 1255 ° C for 29 days) with t_1o -0.48.Al, -0.35Al. An68.7 (heated at 1365 ° C for 42 days) with t_1o-0.52Al, -0.39Al. These data need to be measured by the distribution of Al, Si in plagioclase, and are estimated based on the well-known Δ 131 = 20 (131) -20 (1) parameter and the lattice angle γ. The plot of Δ 131 and γ as a function of the percentage of calcium feldspar molecules is plotted and the plot t_1o- is plotted. The graph plotted with γ gives more accurate results and should be used if the orthoclase content of plagioclase is not yet known, but the lattice parameters must be carefully selected. The determination of Δ 131 is easy , The accuracy with which it is used to determine the state of the structure is somewhat less accurate, but the content of orthoclase must be known.In addition, if t_1o- values of different samples are meaningful for comparison, it is also necessary Amendment of the content of △ feldspar △ 131 impact.