title: In situ chemical speciation of sulfur in calcitic biominerals and the simple prism concept.
abstract: The microstructure and composition of two mollusc shells were investigated using a combination of light microscopy, SEM, EPMA, and XANES. The shells of Pinna and Pinctada are composed of calcite prisms separated by organic walls. The prismatic units of Pinna are monocrystalline, and those of Pinctada are polycrystalline with internal organic radial membranes. High-spatial-resolution XANES maps for the different S species across adjacent prisms show that sulfate is the principal component in both the intraprismatic organic matrices and the outer membranes. Additionally, these maps confirm that the inner structures of the prismatic units are different for both genera. In many ways, the prisms of Pinna and Pinctada are different and invalidate the "simple prism" concept.
authors.affiliation: Laboratoire de Paléontologie, Université Paris XI-Orsay, FRE2566 du CNRS, Bât 504, F-91495 Orsay Cedex, France. dauphin@geophy.u-psud.fr
authors.forename: Yannicke
authors.initials: Y
authors.lastname: Dauphin
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Cuif
authors.forename: Jean
authors.initials: J
authors.lastname: Doucet
authors.forename: Murielle
authors.initials: M
authors.lastname: Salomé
authors.forename: Jean
authors.initials: J
authors.lastname: Susini
authors.forename: C Terry
authors.initials: CT
authors.lastname: Willams
mesh_terms: D000818:Animals; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D004577:Electron Probe Microanalysis / Q000379:methods; D007525:Isoelectric Focusing; D008832:Microchemistry / Q000379:methods; D008854:Microscopy, Electron; D008974:Mollusca / Q000737:chemistry*; D013057:Spectrum Analysis; D013455:Sulfur / Q000737:chemistry*; D014965:X-Rays
chemical_list: D013455:Sulfur; D017886:Durapatite