• journal_title：Mineralogical Magazine
• Contributor：A. Baronnet ; J. P. Cuif ; Y. Dauphin ; B. Farre ; J. Nouet
• Publisher：Mineralogical Society of Great Britain and Ireland
• Date：2008-
• Format：text/html
• Language：en
• Identifier：10.1180/minmag.2008.072.2.617
• journal_abbrev：Mineralogical Magazine
• issn：0026-461X
• volume：72
• issue：2
• firstpage：617
• section：Minerals in Biological Systems

Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to investigate the fine structure of the calcite prisms from the pearl-oyster shell Pinctada margaritifera. The AFM analysis shows that the prisms are made of densely packed circular micro-domains (in the 0.1 μm range) surrounded by a dense cortex. The TEM images and diffraction patterns allow the internal structure of the micro-domains to be described. Each of them is enriched in Ca-carbonate. Hosted in distinct regions of each prism, some are fully amorphous, and some others fully crystallized as subunits of a large calcite single crystal. At the border separating the two regions, micro-domains display a crystallized core and an amorphous rim. Such a border probably marks out an arrested crystallization front having propagated through a previously bio-controlled architecture of the piling of amorphous micro-domains. Compared to recent data concerning the stepping mode of growth of the calcite prisms and the resulting layered organization at the μm-scale, these results give unexpected views regarding the modalities of biocrystallization.