Crystallization of calcite on chitin

Chitin, a nitrogen-containing polysaccharide which is a major component of the exoskeletons of arthropods, was found to be a substrate favouring the deposition of calcite crystals from stable supersaturated solutions at pH 8.50 and at 25 degrees C. The crystallization was studied at constant solution supersaturation thus making it possible for relatively large amounts of the overgrowth to be formed and be identified exclusively as calcite. The induction periods varied markedly with supersaturation. The apparent order found from kinetics data was n = 2, thus suggesting a surface diffusion-controlled mechanism.