> the cif-file below was created from the AMCSD... > The I/Ic value calculated by Match! is 20.5
>>The only ICSD entry has an RIR of over 23, so does >> vermiculite. Why is that so high? I guess these differences in I/Ic are not very significant, since the exact same montmorillonite entry is in ICSD, from which you can export the CIF directly. (In fact I doubt that there are any AMCSD entries that are not also in ICSD). Clays, micas etc are highly layered structures, often with variable amounts of intercalates, and usually not well ordered. They are therefore difficult to model, so the profile fit will be relatively poor. ______________________________________________ Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE <[EMAIL PROTECTED]> +33.476.98.41.68 http://www.NeutronOptics.com/hewat ______________________________________________