Acta Musei Moraviae

Zeolites from the Bernartice quarry near Zruč nad Sázavou (Czech Republic)

An unusual zeolite mineralization was found in fissures and cavities of oligoclasite pegmatite hosted in serpentinite rocks in the active Bernartice quarry, 7 km S from Zruč nad Sázavou, central Bohemia, Czech Republic. The earliest thomsonite-Ca forms light grey acicular crystals, up to 10 mm in size, usually replaced by Mg-Al-Si-(Ca) saponite-like mineral. It is orthorhombic, space group Pncn, with unit-cell parameters refined from PXRD: a 13.108(4), b 13.068(3), c 13.244(4) Å and V 2268.6(9) ų. Barium- and Mg-rich chabazite-Ca forms abundant white rhombohedral, cube-like crystals with vitreous lustre, up to 4 mm in size. It is trigonal, space group R-3m, with unit-cell parameters refined from PXRD: a 13.8055(12), c 14.967(2) Å and V 2470.4(5) ų. The rare chabazite-Mg and chabazite-K form sometimes the youngest 30–40 μm thick margin of chabazite crystals. The youngest harmotome was observed as white prismatic crystals with vitreous lustre up to 0.5 mm in size. It is monoclinic, space group P2₁/m, with unit-cell parameters refined from PXRD: a 9.8581(16), b 14.1494(12), c 8.6854(11) Å, β 124.622(8)° and V 997.0(3) ų. The quantitative chemical composition (by electron microprobe) for all studied zeolites are given.