Crystal structure of a natural and a partially silver-exchanged heulandite
- 1 January 1980
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 9,p. 1511-1514
- https://doi.org/10.1039/dt9800001511
Abstract
The crystal structure of a natural calcium heulandite (Ca)heu and a partially silver-exchanged heulandite (Ag,Ca)heu is reported. The monoclinic crystals, space group C2/m, have cell parameters a= 17.672(6), b= 17.930(6), c= 7.443(4)Å, β= 116.5(1)°, Z= 1, and formula Ca3.1Na1.1K0.1Al7.6Si28.5O72·24H2O (from electron microprobe analysis) for (Ca)heu. For (Ag,Ca)heu a= 17.741(6), b= 17.974(6), c= 7.408(4)Å, β= 116.4(1)°, Z= 1, and the formula is Ca3.1Na0.1Ag1.3Al7.8Si28.2O72·25H2O (from electron microprobe analysis). The final R index is 0.041 for (Ca)heu and 0.051 for (Ag,Ca)heu using 1 863 and 1 414 independent reflections respectively in the least-squares refinement. Chemical analysis and X-ray results show that Ag+ ions have exchanged only univalent cations which are all located in one of the two occupied cationic sites, the other being populated by only Ca2+ ions. These results may be interpreted on the basis of the chemical and structural features of heulandite.Keywords
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