Amorphous biogenic calcium oxalate

Eva Weber, Andreas Verch, Davide Levy, Andy N. Fitch, Boaz Pokroy

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Transition from an amorphous to a crystalline phase and stabilization of amorphous phases is a common strategy in biomineralization. Although no such phenomenon has yet been reported for biogenic calcium oxalate systems, it was recently demonstrated for synthetic calcium oxalate monohydrate (COM). Here we focused on COM raphides—needle shaped biominerals—synthesized by Duckweed. Although these raphides show some birefringence in polarized light, implying their crystallinity, they diffracted poorly when examined by x-ray diffraction in our experiments. By means of transmission electron microscopy coupled with electron diffraction experiments we demonstrated that raphides from Duckweed are completely amorphous in their tip region and transform into a crystalline phase under the electron beam after a few seconds of exposure. To the best of our knowledge, this is the first report on biogenic amorphous calcium oxalate produced by a living organism.

Original languageEnglish
Pages (from-to)132-135
Number of pages4
Issue number2
StatePublished - Feb 2016
Externally publishedYes

Bibliographical note

Funding Information:
The research leading to these results received funding from the European Research Council under the European Union’s Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement (no. 336077). E.W. thanks the Minerva foundation for financial support. The authors thank Matanya Ben Sasson for plant cultivation, Philipp Engel for AFM measurements, and Roland Bennewitz, Lia Addadi and Ingrid Weiss for helpful discussions.

Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • TEM
  • XRD
  • amorphous
  • biogenic
  • calcium oxalate


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