Mineralogy of natural zeolites

Ol-K-01 — Pentasil zeolites from Antarctica from mineralogy to zeolite science and technology 

This paper deals with chemical and crystallographic properties of new and very rare zeolites found at Mt. Adamson (Northern Victoria Leind, Anteirctica). These are gottardiite, mutinaite and tschernichite, the natural counterparts of synthetic NU-87, ZSM-5 and beta, respectively, eind terranovaite and boggsite, whose frameworks are unknown among synthetic materials. Mineral properties are compared with those of the synthetic analogues. 

01-0-02 - Natural zeolites mineralization in the Oligocene-Miocene volcano-sedimentary succession of Central Sardinia (Italy) 

C 3pelletti G. Cerri, M. de GennaIlo A. Langella S. Nai1za G. Padalino, M. Palomba and R. Dipartimento di Scienze della Terra, Universitd di Napoli Federico II, Napoli, Italy Facoltd di Scienze, Universitd del Sannio, Benevento, Italy 

Dipartimento di Scienze della Terra, Universitd di Modena e Reggio Emilia, Italy, alex unimo. it 

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Flanigen, E. M. (1977). Crystal structure and chemistry of natural zeolites, pp. 19— 52. In F. Mumpton, ed. Mineralogy and Geology of Natural Zeolites. Short Course Notes 4. Min. Soc. America. Washington, DC. 

Hay, R. L. Sheppard, R. A. 1981. Zeolites in open hydrologic systems. In Mumpton, F. A. (ed) Mineralogy and Geology of Natural Zeolites. Mineralogical Society of America, Reviews in Mineralogy, Washington, DC, 4, 93-102. 

Boles J. R. (1977) Zeolites in deep-sea sediments. In Mineralogy and Geology of Natural Zeolites, Mineral. Soc. Am. Short Course Notes (ed. F. A. Mumpton). Washington, DC, vol. 4, pp. 137-163. 

F.A. Mumpton, Ed., Mineralogy and geology of natural zeolites, Mineralogical Society of America, Washington, D.C., 1977. 

Fig. 1. Increment of the number of natural zeolites discovered, starting from their appearance on the mineralogy scenery.

The concept of natural zeolite and the connected classification underwent numerous changes in the last seventy years. The first definition, taking care not only of the physical-chemical behaviour, but also of the peculiar structure, is due to Hey in the early 1930s [22]. Further proposals on this subject were made by Smith [23] and Liebau [24], but the discovery of new minerals having only partly the structural features, the chemistry and the properties of the "traditional" zeolites, made necessary the redefinition of the term "zeolite" and the proposition of novel nomenclature rules. A Committee was constituted for this in 1993 by the International Mineralogical Association. After a capillary work lasted about five years a Report was produced on the Recommended nomenclature for zeolite minerals [25]. 

Armbruster, T. Gunter. M.E. Crystal Structures of Natural Zeolites. In Reviews in Mineralogy and Geology Bish, D.L.. Ming, D.W., Eds. Mineralogical Society of America Washington, 2001 Vol. 45. 1-67. 

Armbruster T., Gunter M.E. Crystal structure of natural zeolites. Natural zeolites Occurrence, properties, applications. In Reviews in Mineralogy and Geochemistry 45, D.L. Bish and D.W. Ming (Eds.), Mineralogical Society of America, Washington, D.C., 2001, pp. 1-67. 

The following pages give a review of the chemistry of natural minerals, their typical occurrence in nature and their common mineral associations. This review is used to establish the major groupings of the common clay mineral species as a function of the chemical systems to which they can be related. Because various forms of silica as well as zeolites and organic materials are commonly associated with clays, these materials have been considered in the same manner as the phyllosilicates. It is evident that they have an influence on the clay mineralogy and that they form an integral part of clays in the broad sense of the term. However, they are not normally considered to be clay minerals. 

Mineralogical Composition (in wt %) of Several Natural Zeolite Rocks Employed to Illustrate Some Properties and Applications of These Materials... 

Table 7 lists the currently known aluminosilicate zeolites based upon definition by their unique frameworks following Baerlocker, Baerlocher, Meier, and Olson. It also contains typical unit cell compositions, the lUPAC code, and type localities, but is restrictive in the sense that it does not consider the mineralogical aspects of the study of zeolites. The authoritative body for these is the Subcoimnittee for Zeolite NomenclaMe of the Conunission on New Minerals and Mineral Names of the International Mineralogical Association. Their guidelines have been cited in a recent book on natural zeolites by Tschemich, as follows. 

The natural zeolite community has followed a different path towards a systematisation of its nomenclature. An historically-determined nomenclature in which the crystal structure, the nature of the charge-compensating cation and some thermal properties were taken into account in a non-systematic manner [41] has been replaced by a nomenclature in accordance with the rules of the International Mineralogical Association (IMA) [42], in which both the structure and composition of the mineral are considered. This has led to a substantial increase... 

The NZ was supplied by Nemetali , Vranjska Banja, Serbia Montenegro. The mineralogical composition of the natural zeolite is 90% clinoptiolite and the rest is mordenite and haylandrite. The chemical analysis of the natural zeolite shows that the oxides of silicon, aluminum, calcium and iron are the main constituents while other oxides are present in trace amounts (Table 1). Prior to the experiments, the NZ was dried at 300°C for 48 h in order to remove any traces of moisture or other constituents. The properties of the adsorbents used are listed in Table 2. 

Similarly, XRD of naturally available zeolitic minerals do exhibit variations in their mineralogical features, and hence their properties (viz., stmcture type, pore size dimensions, channel dimensions, surface charge density and electro- negativity), which are the decisive factors related to zeolites and their industrial applications [16, 23, 53, 54]. 

Under the mineralogical name zeolite such sieves occur naturally. For technical purposes due to their higher uniformity only synthetic zeolites are used [10], In the empirical formula Me is an exchangeable cation of the valence n (zeolites are cation exchangers). Molecular sieves have a very regular and orderly crystal structure, which is characterized by a three-dimensional system of cavities with a diameter of 11 A. These cavities are interconnected by pores with a constant diameter. The value of this diameter depends on the type of the exchangeable cation Me. It is 5 A, if in the above formula Me stands for 75% Na+ and 25% Ca2+. 

Researchers [36, 38] have characterized NaOH activated fly ash residues (zeolites) and have ascertained their highly zeolitic nature [7]. It has also been opined [37,39] that the purity of these residues is mainly decided by their cation exchange capacity, mineralogy and morphology. However, study of pore characteristics (viz., size and volume) of such residues has not been explored in detail. 

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