近年来,甘肃建材地质勘探大队对广泛产出于天水地区的白土进行了一些工作,现简述于下: 白土呈白——灰白色,具贝壳——土状断口。水浸湿后呈灰绿——兰灰色,断口变粗糙。白士中的特征矿物是坡缕石、海泡石类粘土矿物。它们在电子显微镜下呈纤维状、束状晶形(见照片)。白土还伴有相当多的绿泥石、蒙脱石和碳酸盐、石英等。白土中的矿物颗粒细小,结晶程度差。白土赋存于天水地区的晚第三纪地层中,该区第三纪的地层大致分为: 5.浅绿色、白色粘土质岩石(白土)夹泥页 In recent years, Gansu Building Materials Geological Exploration Brigade on a wide range of output in the clay in Tianshui some work is now outlined below: white clay was white - gray, with shell - soil-like fracture. After the water soaked gray-green - blue gray, fracture rough. The characteristic minerals in Baishi are palygorskite and sepiolite-type clay minerals. They are fibrous under the electron microscope, bundled crystal (see photo). Clay is also accompanied by a considerable amount of chlorite, montmorillonite and carbonate, quartz and so on. Clay mineral particles in small, poor degree of crystallization. Clay is found in the Late Tertiary strata of the Tianshui area. The Tertiary strata of the area are broadly divided into: 5. Light green, white clay rocks (clay)