Geology and physical properties of Palygorskite from Central China and Southeastern United States

摘要

Relatively new and large palygorskite deposits of Miocene age have been discovered in Anhui and Jiangsu provinces in Central China. The Guanshan deposit is used as an example to compare the geologic occurrence and physical properties of the Chinese palygorskites with the palygorskites produced from the Miocene Florida-Georgia deposits in the United States. The thickness of the Chinese palygorskite beds range from 3 to 6 meters and the Florida-Georgia palygorskite beds range from 2 to 4 meters in thickness. Both the Chinese palygorskites and the Florida-Georgia palygorskites are Middle Miocene in age. The Guanshan palygorskite was formed as the alteration product of basaltic ash deposits in a lacustrine environment. By contrast, the Florida-Georgia palygorskite was precipitated in restricted lagoonal and tidal environments. These different conditions of formation resulted in mineralogical and physical property differences. For example, the Guanshan palygorskite deposit contains a lower quartz and carbonate content than the Florida-Georgia deposits. Also, no phosphate minerals are present in the Guanshan deposit. As a result, the overall palygorskite content is higher in the Chinese deposits. Chemically, the Guanshan deposit has a higher content of MgO and also the viscosity and absorption capacity are higher. In addition, because of the higher palygorskite content, the bulk density is lower. Both the Florida-Georgia and Chinese deposits are high quality and large. However, because they were formed in different depositional environments, there are differences in mineral content and physical properties. (240)