Structural characterization and chemical composition of aragonite and vaterite in freshwater cultured pearls

A. L. Soldati*, D. E. Jacob, U. Wehrmeister, W. Hofmeister

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

Vaterite and aragonite polymorphs in freshwater cultured pearls from mussels of the genus Hyriopsis (Unionidae) were structurally and compositionally characterized by Raman spectroscopy, Micro computer tomography, high resolution field emission scanning electron microscopy, electron microprobe analysis and laser ablation inductively coupled plasma mass spectrometry. The appearance ofvaterite in pearls is related to the initial stages of biomineralization, although we demonstrate that vaterite can not be a precursor to aragonite. It is not related to a particular crystal habit and therefore does not have a structural functionality in the pearls. Larger contents of elements typically bound to organic molecules, such as P and S in vaterite, as well as larger total organic contents in vaterite as opposed to aragonite in conjunction with larger concentrations of Mn2+ and Mg2+, imply a stabilizing role oforganic macromolecules and X2+ ions for biological vaterite. Distribution coefficients between aragonite and vaterite for provenance-independent elements, such as Mn and Mg (0.27 and 0.04, respectively) agree very well with those observed in fish otoliths.

Original languageEnglish
Pages (from-to)579-592
Number of pages14
JournalMineralogical Magazine
Volume72
Issue number2
DOIs
Publication statusPublished - 2008
Externally publishedYes

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