ABSTRACT

The fluoride content of skeletal magnesian calcites increases with increasing magnesium carbonate content of the calcites. And the determination of the fluoride content of various carbonate rocks from Daito-jima shows that fluoride tends to be concentrated in protodolomites rather than in calcites. This trend was observed in the laboratory experiment on the coprecipitation of fluoride and magnesium ions with calcium carbonate. The results show that the fluoride content of carbonate sediment is controlled by the concentration of magnesium ions in a parent solution and also by the magnesium carbonate content of carbonate sediment.