The effect of solution stoichiometry on mineral growth rates has been well studied using atomic force microscopy (AFM) on barite and calcite. For both of these minerals, step velocities are maximized at cation-to-anion ratios close to or greater than unity and decrease with changes in ratio. However, the kinetics of growth of other sparingly soluble minerals is less well understood. Magnesite is of particular interest as it is isostructural with calcite, however while calcite grows readily at low temperature conditions, magnesite precipitates much slower. Here we present research on magnesite step velocities as a function of the magnesium-to-carbonate ratio at multiple saturation states and 80�C. We found little difference in step velocities as a function of ratio at the lowest saturation index studied, however as the saturation index was increased, step velocities were greater at a ratio near unity and decreased at more extreme ratios, similar to behavior observed with calcite and barite. The implications for this finding is that the reaction mechanism for attachment and detachment of cations and anions to step edges plays an important role in determining the growth behavior of a mineral.

Magnesite growth rates as a function of the aqueous magnesium-to-carbonate ratio

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.