五年来我们在华北广大地区勘探了很多耐火粘土和铝土矿,岩矿研究室相应地做了不少的室内研究工作。在最初工作的时候我们感到非常困难,这是由于粘土矿物多呈隐品质[0.01～0.0001(0.0002)mm]或胶凝体[0.0001(0.0002)mm～50A],或受杂质浸染,不能只靠显微镜来鉴定。何况某些粘土矿物的光学性质相同或近似,而它们又不是同 In the past five years we have explored a great deal of refractory clay and bauxite in vast areas in North China. Rock and Mineral Research Office has done a lot of indoor research accordingly. We were struggling with the initial work because clay minerals were mostly invisible quality [0.01-0.0001 (0.0002) mm] or gel [0.0001 (0.0002) mm to 50 A] or contaminated with impurities and could not be relied on Microscope to identify. Moreover, the optical properties of some clay minerals are the same or similar, but they are not the same