A sample of the zeolite paulingite from the locality Vinaricka Hora was investigated by means of chemical, thermal, powder and single crystal X-ray methods. The fully transparent, colourless to pale yellow crystals exhibit the form {110} and occur together with phillipsite. The chemical composition is (Ca (sub 2.57) K (sub 2.28) Ba (sub 1.39) Na (sub 0.38) ) (Al (sub 11.55) Si (sub 30.59) O 84 ).27H 2 O, Z = 16 with minor amounts of Mg (<0.05), Sr (<0.13), Mn (<0.01), and Fe (<0.04). The chemical differences from previously described paulingites are a high Ba-content, a lower Si/(Al+Fe) ratio of 2.64, and a reduced water-content. The calculated density is 2.098 g cm (super -3) , and the observed refractive index is 1.482(2). The dehydration behaviour is characterized by a main weight loss from 24-190 degrees C (-11.2 wt.%, congruent to 21H 2 O) and a minor weight loss from 190-390 degrees C (-3.1 wt.%, congruent to 6H 2 O). The rehydration capability was proven up to 150 degrees C. The dehydration process during the main weight loss is accompanied by a reduction of the cell volume of 11%. The refined lattice parameters of the X-ray powder data are a = 35.1231(5) Aa and a = 33.7485(8) Aa of an untreated and a dehydrated sample, respectively. A breakdown of the paulingite structure can be observed while the remaining water content decomposes. The single crystal X-ray refinement of this chemically different sample material derived three main cation positions, which are inside a so called paulingite or pi -cage (Ca), between 8-rings of neighbouring pi -cages (Ba), and in the centre of the non-planar 8-rings of the gamma -cage (K). Further partially occupied cation positions (Ca,Na) were located in the planar 8-rings of the alpha - and gamma -cages. No positions within the double 8-membered rings were detected. The water is localized around the main cation positions and in three clusters of partially occupied sites.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not currently have access to this article.