• journal_title：Clays and Clay Minerals
• Contributor：Fernando Nieto ; Marcello Mellini ; Isabel Abad
• Publisher：Clay Minerals Society
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.1346/CCMN.2010.0580511
• journal_abbrev：Clays and Clay Minerals
• issn：0009-8604
• volume：58
• issue：5
• firstpage：721
• section：Articles

The arguments of Vidal et al.(2010) against the incorporation of H₃O⁺ rather than of H₂O in the interlayer position of illite are disputable. Stoichiometric arguments do indeed suggest that the excess water in the Silver Hill illite is in the form of H₃O⁺. No reason exists to assume less water content in the IMt-2 sample than in those determined by Hower and Mowatt (1966) and confirmed by the thermogravimetric analyses of Nieto et al.(2010). The comparison between element contents calculated from end-members and those from the structural formula in figure 1 of Vidal et al.(2010) is not an experimental result, but rather a trivial mathematical artifact. The fact that thermodynamic models, based on the incorporation of interlayer H₂O in illite, may provide reasonable estimates neither proves nor disproves the presence of H₃O⁺; this is because thermodynamics is a non-atomistic, macroscopic approach.