Nacre organic matrix has been conventionally classified as both water-soluble and water-insoluble ,basedonits solubility in aqueous solutions after decalcificationwith acid or EDTA. Some characteristics (aspartic acid-rich, silk-fibroin-like content) were specifically attributed to either one or the other. The comparative study on the technique of extraction (extraction with water alone vs. demineralization with EDTA) presented here, seems to reveal that this gen-erally accepted classification may need to be reconsidered
