A new insight on the role of Mg in calcite

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 2p_z atomic orbitals (AOs) toward the O 2p_x and 2p_y AOs for impurity nearest oxygens. On the other hand, the high Mg impurity concentrations make the chemical bonding in calcite more ionic. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011