What is the difference in organic matrix of aragonite vs. vaterite polymorph in natural shell and pearl? Study of the pearl-forming freshwater bivalve mollusc Hyriopsis cumingii

► WSM, ASM and AIM are extracted from shell nacre, aragonite and vaterite pearls. ► Hydrophobic residues are major components of all extracts. ► Unbalanced acidic residues rates exist in WSM vs. ASM and in aragonite vs. vaterite. ► A 140 kDa material is specific for aragonite sample in WSM. ► All acid soluble extracts reveal 50 kDa components.