On the crystal structure of the zeolite heulandite

  • A. Alberti


Heulandite is a zeolite of ideal composition (Ca,Na2)Al2Si7O18·6H2O which crystallizes in the monoclinic system, witha=17.718,b=17.897,c=7.428 Å and β=116°25′; Z=4. As heulandite is strongly pseudocentrosymmetric its structure has been refined, by the least-squares method, in space groupsCm, C2 andC2/m. The “more probable” space group results to beCm. A detailed description of the tetrahedral framework has been given byMerkle andSlaughter (1968). The average distances (Si,Al)−O within each tetrahedron show a partial order of Si and Al atoms in the framework. The observed order is different from that reported byMerkle andSlaughter. Half of the exchangeable cations sites are in sevenfold coordination and half in eightfold coordination; according toMerkle andSlaughter, on the contrary, they are always eightfold.


Crystal Structure Zeolite Geochemistry Exchangeable Cation Average Distance 
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Über die Kristallstruktur des Zeoliths Heulandit


Heulandit ist ein Zeolith der idealen Zusammensetzung (Ca,Na2)Al2Si7O18 ·6H2O, der monoklin mita=17,718,b=17,897,c=7,428 Å und β=116°25′ kristallisiert; Z=4. Da Heulandit ausgeprägt pseudo-zentrosymmetrisch ist, wurde seine Struktur mittels der Methode der Kleinsten Quadrate in den RaumgruppenCm, C2 undC2/m verfeinert. Es ergibt sich, daß die “wahrscheinlichere” RaumgruppeCm ist. Eine detaillierte Beschreibung des Tetraedergerüstes wurde vonMerkle undSlaughter (1968). gegeben. Die durchschnittlichen (Si,Al)O-Abstände innerhalb einer Tetraederart zeigen eine teilweise Ordnung von Si und Al im Gerüst an. Die beobachtete Ordnung ist verschieden von jener, dieMerkle undSlaughter angegebeb haben. Je die Hälfte der Lagen der austauschbaren Kationen hat 7- bzw. 8-Koordination; im Gegensatz dazu habenMerkle undSlaughter durchwegs 8-Koordination angegeben.


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Copyright information

© Springer-Verlag 1972

Authors and Affiliations

  • A. Alberti
    • 1
  1. 1.Istituto di Mineralogia e Petrologia dell'Università di ModenaModenaItaly

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