LOW TEMPERATURE ABIOGENIC SYNTHESIS OF DOLOMITE

Abstract

Endowed with the theoretical knowledge of carbonate evaporation and the precipitation of CaMg carbonates from aqueous solutions the authors systematically researched the low temperature: formation of dolomite-like carbonates. The results obtained at 40 degreesC indicate that the formation of rhombohedral CaMg carbonates depends on the solid matter/water ratio (solidus index Is). The higher the ratio, the mure MgCO3 enters into the carbonate structure. The results also confirm a gradual transition of these relationships from calcite, through Mg-calcite, Ca-dolomite and Q-dolomite (Quasi-dolomite) to Mg-dolomite (Ca44Mg56). The structure of these synthesised carbonates: is disordered, much like their natural counterparts in lagoons, sabkhas, soil:; etc. When studying Ca-dolomite in the laboratory it was found to restructure into stable dolomite at 100 degreesC and into calcite at 180 degreesC. Synthetized dolomite (Ca50Mg50) does not show superstructural X-ray reflections and hence it was denominated as a Quasi-dolomite (Q-D).