“…The se quence of the inhibition effect of ions on the Mg" ion adsorption is as follows: phos phate > Ba2+, F > Ca2+. This sequence is consistent with that of the power of ions forming calcitic carbonate from solution containing Mg" ions (53.5 mM): phosphate (0.05-0.5 mM) > citrate(0.2 mM, 1966), Ba2+(0.25 mM, 1979a), F-(0.5 2.5 mM) > alkalinity(10-50 mM, 1983) > Ca2+(50 mM, Tomiyama and Kitano, 1984 Several authors have mentioned the polymor phic crystallization of calcium carbonate. The first concept is based on the thermodynamical consideration (Berner, 1975): Dissolved Mg" ions in solution, which favor aragonite precipita tion from the solution, have a strong retarding effect on the calcite growth, whereas they have no effect on the aragonite growth.…”