Figure 1
Microstructure of nacre.
Natural nacre has a brick-mortar-bridges microstructure where inorganic calcium carbonate layers are held together by organic protein "glue". Whereas, the inorganic portion represents 95% of the volume of nacre, its highly specidic properties (in particular its high toughness) are due to the interaction of this inorganic component with the organic phase that is found between the calcium carbonate platelets (image © Science)