Intra-crystalline protein diagenesis (IcPD) in Patella vulgata. Part I: Isolation and testing of the closed system

► Successful isolation of an intra-crystalline fraction of proteins from Patella vulgata. ► Investigation of the mineralogical composition of P. vulgata by X-ray diffraction. ► Optimisation of the sampling strategy for AAR geochronology on P. vulgata. ► Testing of the intra-crystalline proteins as a closed system during diagenesis. ► P. vulgata is shown as a suitable substrate for IcPD geochronology.