The classfication of fractures in coal

The field and laboratory investigation on the coal in the areas including Wulan,Rujigou,Lulin,Jincheng,Pingdingshan,Jiaozuo,Jiyuan,Xin'an,and Yima have been finished recently.The results show that according to the genesis and morphology,the fractures in coal can be divided into 4 classes,7 groups,and 17 types.the characteristics of each class or type are described in this paper.