Physical, chemical, and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland.

Physical, chemical, and mineralogical investigations of mineral concretions found in the human pineal gland were performed by means of optical microscopy and modern techniques of analytical electron microscopy and x-ray powder diffraction (OM,SEM + EDS,TEM + EDS,XRD). The mineral concretions were found to be nano-crystalline carbonate-hydroxyapatite with a mean Ca/P molar ratio equal to 1.65, very close to the theoretical value of 1.67. TEM and XRD showed that this is the only inorganic phase present in the concretions without the presence of amorphous phosphate as precursor. SEM and EDS, performed on cross-sectioned samples, showed a concentric layered distribution of the inorganic phase permeated by organic matter, within the concretions, with a slight increasing of the Ca/P molar ratio in their internal part.