Zeolites in Tertiary coal from the Çayirhan mine, Beypazari, Turkey

Abstract

The study focuses on the mineralogy of the upper coal seam accumulated at the top of the Çoraklar Formation (Miocene), Beypazari, Turkey. This coal seam is laterally extensive and averages 3.0 m thick, varying from 1.0 to 4.9 m. Analcime and clinoptiolite comprise up to 80% of the mineral matter (which also includes feldspars, quartz and pyrite and traces of dolomite, clay minerals and apatite) in the coal from the Cayirhan mine. Zeolites were formed when sodium-rich solutions altered aluminosilicate epiclastic material derived from contemporaneous volcanic activity. The allocthonous organic matter accumulated as a result of detrital plant and epiclastic material from an adjacent fresh-water environment being washed into a saline lake in sufficient quantities to form peat with a high mineral matter content (29.7% mean mineral matter content in raw coal). Subsequent syngenetic alteration of the volcanic glass incorporated into the peat resulted in zeolite formation. Alteration of sodium-rich epiclastic material by sodium-rich solutions resulted in the formation of analcime, whilst alteration of calcium-rich epiclastic material by sodium-rich solutions resulted in the formation of clinoptilolite.