Several important equilibrium Si isotope fractionation factors among minerals, organic molecules and the H 4 SiO 4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth’s surface environments. The results reveal that, in comparison to aqueous H 4 SiO 4 , heavy Si isotopes will be significantly enriched in secondary silicate minerals. On the contrary, quadra-coordinated organosilic...