This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association, Commission on New Minerals and Mineral Names. In a working definition of a zeolite mineral used for this review, structures containing an interrupted framework of tetrahedra are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundant in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix, except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on the ratio Si : Al except for heulandite (Si : Al < 4.0) and clinoptilolite (Si : Al ≥ 4.0). Dehydration, partial hydration, and overhydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term "ideal formula" should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows: brewsterite-Sr, -Ba, chabazite-Ca, -Na, -K, clinoptilolite-K, -Na, -Ca, dachiardite-Ca, -Na, erionite-Na, -K, -Ca, faujasite-Na, -Ca, -Mg, ferrierite-Mg, -K, -Na, gmelinite-Na, -Ca, -K, heulandite-Ca, -Na, -K, -Sr, levyne-Ca, -Na, paulingite-K, -Ca, phillipsite-Na, -Ca, -K, and stilbite-Ca, -Na. Key references, type locality, origin of name, chemical data, IZA structure-type symbols, space-group symmetry, unit-cell dimensions, and comments on structure are listed for 13 compositional series, 82 accepted zeolite mineral species, and three of doubtful status. Herschelite, leonhardite, svetlozarite, and wellsite are discredited as mineral species names. Obsolete and discredited names are listed.Keywords: zeolite nomenclature, herschelite, leonhardite, svetlozarite, wellsite, brewsterite, chabazite, clinoptilolite, dachiardite, erionite, faujasite, ferrierite, gmelinite, heulandite, levyne, paulingite, phillipsite, stilbite. SOMMAIRECe rapport contient les recommandations à propos de la nomenclature des zéolites, telles qu'approuvées par l'Association minéralogique internationale, commission des nouveaux minéraux et des noms de minéraux. Dans la définition d'une zéolite retenue ici, les structures contenant une trame interrompue de tétraèdres sont acceptées dans les cas où les autres propriétés satisfont les critères de cette famille de minéraux. De plus, il peut y avoir remplacement complet de Si et Al par d'autres éléments. Des espèces distinctes font partie de séries de compositions dont l'agencement topologique est le même, le cation dominant ne faisant pas partie de la trame ...

This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association Commission on New Minerals and Mineral Names. In a working definition of a zeolite mineral used for this review, interrupted tetrahedral framework structures are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundant in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on Si : Al ratio except for the heulandite (Si : Al < 4.0) and clinoptilolite (Si : Al ≥ 4.0) series. Dehydration, partial hydration, and over-hydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term "ideal formula" should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows:

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A check of recent articles in Acta Crystallographica Section C shows that some confusion exists about the definition of the equivalent isotropic displacement factor Ueq. A common error is the use of the non-orthogonalized tensor U for the calculation of Ueq in non-orthogonal crystal systems. In addition, a number of cases have been found where at* is confused with a t or B with fl, or where the wrong factors are used to relate Ulj or fllj to Btj or vice versa. Ue~'S for the different crystal systems are derived from the general Y YUaaaa

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