Letter to the editor on fougerite

B.C. Christiansen, K. Dideriksen, L.L. Skovbjerg, S. Nedel, S.L.S. Stipp

Research output: Contribution to journalComment/debate

2 Citations (Scopus)


Fougerite (IMA 2003-057) was accepted by the Commission on New Minerals and Mineral Names of the International Mineralogical Association (IMA) in 2004 as a new mineral to represent the green rust (GR) family. The data on which it was approved, however, are inconsistent. X-ray diffraction patterns from the Fougères soils contain no peaks that could meaningfully be attributed to a GR phase. The sequential dissolution procedure used to identify GR in the soils was not rigorously tested for selectivity. If indeed it is selective, the results indicate the presence of 40-78% Fe in minerals other than GR. Other Fe-bearing phases were not included in the interpretation of the spectroscopy data that were presented. The data are consistent with the presence of Fe-bearing clays and other silicate minerals. In light of the ambiguous and conflicting data, we recommend that the case for fougerite as a mineral be re-evaluated by the IMA.

Original languageEnglish
Pages (from-to)3-9
Number of pages7
JournalClays and Clay Minerals
Issue number1
Publication statusPublished - Feb 2011
Externally publishedYes


  • Fougerite
  • Green rust
  • IMA 2003-057
  • Mineral ambiguity

Programme Area

  • Programme Area 2: Water Resources


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