J. Aizenberg et al., STABILIZATION OF AMORPHOUS CALCIUM-CARBONATE BY SPECIALIZED MACROMOLECULES IN BIOLOGICAL AND SYNTHETIC PRECIPITATES, Advanced materials, 8(3), 1996, pp. 222
Communication: Composite structures in which amorphous and crystalline
phases coexist are formed by some organisms. The spicules of the spon
ge Clathrina are shown to be composed of a crystalline calcitic core a
nd an outer layer of amorphous CaCO3 (see figure). The latter material
, normally a highly unstable mineral, is stabilized in vitro by macrom
olecules extracted from the outer sponge spicule layer. The combinatio
n of crystalline and stabilized amorphous phases may have important im
plications for materials applications.