ABSTRACT

The effect of citrate, malate, lactate and acetate ions in a parent solution on the incorporation of fluoride ions into formed calcite has been studied experimentally. Citrate ions in a parent solution containing no magnesium ions increase intensively the amount of fluoride ions incorporated into magnesium-free calcite, and malate ions do so but moderately, while lactate and acetate ions have little effect on the incorporation of fluoride ions into calcite. The amount of fluoride ions incorporated into low Mg-calcite (smaller than 4% magnesium carbonate) formed from a parent solution containing magnesium ions but no citrate ions remarkably increases with increasing magnesium carbonate content of the formed low Mg-calcite. This trend is in agreement with that observed in marine calcareous skeletons (OHDE and KITANO, 1980). The amount of fluoride ions incorporated into high Mg-calcite formed from a parent solution containing both magnesium and citrate ions is large. The fluoride amount slightly increases with increasing magnesium carbonate content of the formed high Mg-calcite.