A new insight on the role of Mg in calcite

Abstract

Magnesium is a key determinant in calcite (CaCO3) mineralization having a notable significance upon the carbonate growth. Magnesium is also present in CaCO3 mineral scale formation which is a persistent and expensive problem in oil and gas production. In the present work, we attempt to treat CaCO3 calcite mineral bulk inducing different concentrations of Mg impurity. The study is done using a quantum-chemical computer code based on the Hartree-Fock method. It is found that small Mg impurity concentrations produce a significant distortion of the defect-closest O atoms thus developing local microstructures being distinct to those of the original calcite structure. This structural alteration is accompanied by the electron density redistribution from the O 2pz atomic orbitals (AOs) toward the O 2px and 2py AOs for impurity nearest oxygens. On the other hand, the high Mg impurity concentrations make the chemical bonding in calcite more ionic. Copyright © 2010 Wiley Periodicals, Inc.