Occurrence and properties of natron in the Miocene lacustrine Beypazari basin, Turkey

Abstract

Natron, Na2CO3 . 10H(2)O, is a rarely forming evaporite mineral, which precipitates under the unique physicochemical conditions of Na wt.%, temperature and HCO3/CO3. Natron is observed in the upper parts of the lower trona level of the Beypazari Neogene volcanosedimentary sequences, where exist two trona beds between 260 in and 285 m depths. In this study, natron and some other soda minerals were examined by detailed geochemical, physicochemical and experimental studies. Euhedral natron crystals were determined sporadically within sedimentary beds. Based on our studies, it is postulated that white, soft and platy-fibrous natron minerals formed in the microenvironments within the rhythmic series of marls and claystones, are precipitated from pore solutions under the conditions of low temperature and high CO3/HCO3 ratio during the end of the first precipitation of the trona deposits. The contents of the trace elements were measured using wet chemical analyses; XRD, DTA and SEM techniques were performed, and the results were evaluated based on the formation conditions of the mineral.