Abstract
Samples of natural fine-grained carbonate sediment from Florida Bay, Florida, undergo mole-for-mole cation exchange with aqueous solutions of MgCl2 and CaCl2 in the laboratory. The exchange reaction, which involves the surface of the grains of sediment, can be essentially described by a simple mass action-law equation. Enrichment of Mg++ beyond the amounts found within particle interiors should take place on the surface of CaCo3 sediments immersed in sea water; it may be on both exchangeable and unexchangeable sites.