The Geology of silex occurence at Çan (Çanakkale) region and industrial evaluation

VII ABSTRACT Silex is an important grinding raw material in ceramic industry which has been found in Tertiary volcanic rocks as irregular bodies in Biga Peninsula in Turkey. In the study area the silex occurence have been outcropped mainly in tuffs and lavas of trachyandesite as steep colins. İt has been inferred that the silex occurences were formed in the centre of the advanced argillic zone due to alteration Miocene trachyandesites in epithermal conditions. It has been concluded that silicification was formed as two consecutive events either devitrification of volcanic glass or crystallisation of silica in the fractures of the rock. The field observations and the mineralogic- petrographic studies show that advanced argillic zone can be identified in to three different zones as : 1- Massif silicified zone 2- Silicified-argilic zone 3- Argilic zone Massif silicified zone is the most widespread unit of advanced argilic alteration. It is possible to divide this zone into two subzone as - massif silicified zone -porous silicified zone. The mineral paragenesis of the advanced argillic zone has been determined as quartz ( a quartz and its polymorphes ), kaolinite, alunite and hematite. In economic aspect the SİO2 content purity and resistance to corrosion are the critical factors to apprise the silica as a raw material. Collected samples from the survey area have SİO2 contents more than % 90 Si02 and Fe203 contents less than % 0,9 Fe203. T C YOKSEICÖCRETİM KURUUJ 0OK0MANTASYGN MSBMSMvm With the aim of establishing the properties of these silex ; corrosion, acide and cook tests were applicated to the collected samples. Corrosion tests inferred that fine grained crystals have low values; however coarse grained crystals have high values. Acid tests were applicated either to sedimantery flint stones which has been imported or flint stones from survey area related to volcanism. The flint stones which have sedimentary origin have the loss of weight due to reaction with acidic. Whereas the flint stones of Çanakkale region don't have any reaction with acide. The result of cook tests indicates that Çanakkale silex doesn't show any Fe vomit and sticking except Güvemalanı area. This results reveal that silex of güvemalanı have high alkali content. Geological, mineralogic and petrographic studies show that, the silex with volcanic origin of Çanakkale region, have high qualities in industrial manner and physical properties of them are more availible than those of sedimantery origin.