Mineralogy, geochemistry of altered tuff from Cappadocia (Central Anatolia) and its use as potential raw material for the manufacturing of white cement

The present study deals with mineralogy, geochemistry and uses of altered tuff from Cappadocia (Central Anatolia) as a potential raw material for the manufacturing of white cement. Mineralogical analyses show that altered tuffs are mainly composed of quartz and kaolinite. In some samples minerals such as jarosite, illite, smectite, sanidine and calcite have also been detected. A widespread, intensive hydrothermal alteration zone has developed across a NE-SW striking fault in the study area (Turkmenlik Hill). The field observations and the results of the analyses show that there are some changes in mineralogical and chemical composition across this fault zone. The central part of the fault zone shows an intensive silicification (> 85% SiO2). The amount of kaolinite increases towards the outsides; the outermost zone is composed of smectite (illite) in association with quartz and kaolinite. This phase zonation supports the proposition that those minerals were probably formed by hydrothermal activity. The presence of jarosite in some samples indicates that the hydrothermal solution might have had acidic character.