The distribution of elements in the alteration of feldspatic minerals

Feldspar (alkali feldspar and plagioclases) and in recent years feldspathoid minerals are used as raw materials in the ceramic-glass industries. The igneous rocks such as granite, syenite and foid syenite which mainly contain these minerals have the potential to be raw materials. Some inclusions within the feldspatic minerals affect extremely negatively the desired values for raw material. In this study, the effective processes in the alteration of feldspatic minerals within the Özvatan foid syenites, the effects of alteration minerals in the raw material were evaluated and the effects of the elements released by alteration on the environment were revealed. The foid syenites consist of nepheline, orthoclase, plagioclase, cancrinite, sodalite, amphibole, biotite, pyroxene, melanite with a rare amount of sphene, zircon, apatite and fluorite. The contents of the sericite and kaolinite, which are formed as a result of an alteration of these rocks, increase in direct proportion to alteration degree. As a result of the alteration index values, foid syenites samples show the low degreed decomposed property. According to the calculated mobility index (MI) from chemical analyses, there is a quantitative decrease in the major oxides such as SiO2, Al2O3, Na2O, K2O, CaO and Fe2O3 in the foid syenites. In accordance with the all data, Özvatan foid syenites have been exposed both weathering and hydrothermal alteration and the effect of hydrothermal alteration are observed more frequently in the altered rock. While the excess of diaclase structures within the rock provides ease of operation, on the other hand, it accelerated the weathering and alteration processes.