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 ...

he deposits of Pleistocene Lake Tecopa cover about 90 square miles along the Amargosa River in southeastern Inyo Co'unty. These deposits consist chiefly of mudstone and inter-be~ded rhyolitic vitric tuffs that interfinger marginward with co~rser clastic sediments. A total of 12 tuffs, 2 inches to 13 fet=tt thick, were recognized in the 220 feet of exposed section. Tliey are mainly the result of ash falls directly into the lake, although the upper parts of some contain reworked material. This report summarizes the physical properties, chemistry, and areal distribution of those silicate minerals that formed in the tuffs during diagenesis.Zeolites, monoclinic potassium feldspar, searlesite, clay minerals, and opal occur in the altered tuffs. The zeolites are mainly phillipsite, clinoptilolite, erionite, and in trace to minor amounts, analcime and chabazite. Clay minerals are nearly ubiquitous and occur in trace to major amounts associated chiefly with zeolites and potassium feldspar. Most beds contain two or more zeolites, but some beds are monomineralic. Potassium feldspar also locally forms monomineralic beds.Zeolites are locally associated with relict glass; potasssium feldspar and searlesite are locally associated with zeolites, but nowhere has potassium feldspar oc searteslite been round associated with relict glass. Textural evidence shows that some po•tassium feldspar and searlesite replace phillipsite and suggests that all potassium feldspar and searlesite in the tuffs formed from phillipsite and other early diagenetic zeolites rather than directly from the rhyolitic glass.Three diagenetic facies recognized in the tuffs have fresh glass, zeolite, and potassium feldspar or searlesite as their diagnostic constituents. The fresh-glass facies is alrong the lake margin and is succeeded basinward by the zeolite facies and then by the potassium feldspar facies in the central part of the basin. The boundary between the zeolite and potassium feldspar facies bulges basinward at the inlets to Lake Tecopa. Original textures and sedimentary structures are generally preserved in tuffs of the zeolite and potassium feldspar facies. Preservation of these features in altered tuffs that are laterally equivalent to tuffs of the fresh-glass facies is convincing evidence that the present differences in composition and mineralogy are due to postdepositional processes. Experimental work by other mineralogists indicates that the formation of zeolites and feldspar is favored over clay minerals by a relatively high alkali ion to hydrogen ion activity ratio. The distribution and the gradational character of the facies are undoubtedly due to a chemical zonation of the pore water during diagenesis. The pore water was "fres'h" near the margin and inlets of the lake but increasingly alkaline and saline bas:inward. This zonation was probably inherited from the depositional environment. Water of Lake Tecopa was probably moderately to highly saline with a pH of 9 or higher, except near the lake margin.Solution of the 'rhyolitic glass by alkal...

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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