Structural and Chemical study on magma crystallization and mineral melting processes.

（1）玻璃的结构研究首先，分析了岩浆主要成分之一的Al_2O_3-SiO_2系统的玻璃结构。这些玻璃中的许多Al原子具有四面体，并且八面体Al的数量可能很小。这一结果与MonteCarlo模拟得到的模型结构一致。分析了长石（NaAlSi_3O_8-CaAl_2Si_2O_8）玻璃的结构。从观察结果可以看出，随着Ca和Al原子的增加，密度增加，摩尔体积减小，这可以用玻璃结构中T-O-T角（T=Si，Al）的减小来解释。B）用X射线衍射和拉曼光谱研究了阴极射线管玻璃中硅酸盐熔体富Sb μ晶的析晶过程，发现该晶体具有蔷薇辉石型结构。分析了硼镁石晶体周围富锑玻璃相的结构。结果表明，该玻璃的网络结构发生了较大的畸变，这种畸变可能与蔷薇辉石的析晶有关。分析了天然火山玻璃（黑曜岩玻璃）的结构，发现其具有液相和小晶相。结果表明，该黑曜岩中存在不含正常液相的亚μ相.该相可能与黑曜石中的微晶相有关。采用二元硅酸盐体系结晶过程数值实验研究了火山岩结构的形成过程。火山岩和深成岩之间的结构差异可能是由它们不同的冷却速率造成的。c）所有项目成员都讨论了这些结果，我们编写了一些科学论文。

Principle results on the study on magma crystallization and mineral melting processes were followed.a) Structural studies of glassesFirstly, The glass structures of Al_2O_3-SiO_2 system that is one of the principle components of magma were analyzed. Many Al atoms in these glasses have tetrahedra and the number of octahedral Al may be small. This result is consistent with the model structure derived from Monte Carlo Simulation. The structures of feldspar (NaAlSi_3O_8-CaAl_2Si_2O_8) glasses were also analyzed. From the observations, it was evident that the density increase and molar volume decrease with increases of Ca and Al atoms could be explained by decrease of T-O-T angle (T=Si, AL) in the glass structure.b) Study on crystallization of silicate meltSb rich μ size crystals in cathode ray tube glass were investigated by X-ray diffraction and Raman spectra measurements and revealed that this crystal had romeite type structure. The structure Sb rich glass phase surrounding romeite crystal was also analyzed. It was evident that the network structure of this glass was rather distorted and this distortion may relate to crystallization of romeite. The structure of natural volcanic glass (onsidian) which had liquid and small crystalline phases was also analyzed. Obtained results show that this obsidian has sub-μ size phase which is not included normal liquid phase. This phase may be related in crystallite phase in obsidian. Numerical experiments on crystallization for binary silicate system were adopted for study on formation process of textures of volcanic rocks. The texture differences between volcanic and plutonic rocks may be caused by their different cooling rate.c) These results were discussed by all project members and we prepared some scientific papers.