ABSTRACT:  Many of the Turkish kaolin deposits are hydrothermal type although some of the country`s major deposits are believed to have originated from weathering. Intensive silicification and limonitization and the associated hydrothermal ores such as mercury, antimony, fluorite and sulfur minerals are taken as indication to hydrothermal origin. The thickness of the hydrothermal kaolin deposits controlled by volcanic phenomena is, generally speaking, comparatively less, where as their lateral persistances often considerable* Those oecuring within the fault zones, however, attain considerable thickness — locally as much as 100 meters. Bulk of the Turkish kaolin deposits formed by hydrothermal actions are presently considered uneconomic due to extensive alunitization, and the associated pyrite, and sulfur formations and 3b, Hg, Pb, Zn, Cu, Ni, and Co - sulfide minerals. Chemical processes associated with kaolinization are believed to have led to the high concentrations of metallic ores, which in turn caused considerable changes in the pH - conditions of the deposit, thus resulting in marked increases in the illite and montmorülonite content of these deposits*