TYPOMORPHIC PECULIARITIES OF BIOTITES FROM DIFFERENT GENETIC TYPES OF GRANITE IN THE HENGDUANSHAN REGION
Xie Yingwen;Zhang Yuquan Institute of Geochemistry, Academia, Sinica, Guiyang
The chemical compositions, trace elements, structures and physical prope-rties of biotites from different genetic types of granite in the HengduanshanRegion have been studied in this paper. Based on their chemical compositions,these biotites can be divided into three subspecies: magnesium-rich biotite (MF=1. 3-1. 5), magnesio-biotite (MF=1. 0-1. 3), and iron-rich biotite(MF=0. 5-1. 0). Each of them has its own features and is closely related to the originof the granites. Therefore, biotite is one of the most useful typomorphicminerals for the different genetic types of granite.