Cowlesit a doprovodná mineralizace z vrchu Hackenberg u České Kamenice (Česká republika)

Publication Type:Journal Article
Year of Publication:2014
Authors:Pauliš, P, Hrůzek, L, Janeček, O, Sejkora, J, Malíková, R
Journal:Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze
Volume:22
Issue:2
Start Page:248
Pagination:13
ISSN:1804-6495
Keywords:analcime, chabazite-Ca, chemical composition, cowlesite, Czech Republic, erionite-Ca, gismondine, Hackenberg near Česká Kamenice, lévyne-Ca, natrolite, phillipsite-K, powder X-ray diffraction data, thomsonite-Ca, unit-cell parameters
Abstract:

Nine zeolites were found at the Hackenberg hill, a very interesting mineralogical site located 2 km southwest from Česká Kamenice (northern Bohemia, Czech republic). These zeolites were found in the cavities which are located at the contact of basalt, volcanic tuffs and breccia. Cowlesite forms white hemispherical aggregates with size up to 10 mm, which belongs to the world´s largest examples of this species. The unit cell parameters of cowlesite, refined from powder X-ray data, are a 11.267(7), b 15.255(7), c 11.992(8) Å and V 2061(5) Å3. Chemical analyses of cowlesite correspond to the empirical formula Ca0.90Na0.12Mg0.01K0.01(Al1.89Si3.10)O10·4 H2O. Lévyne-Ca forms hexagonal tabular colorless crystals with an average size of 2 - 4 mm. The unit cell parameters of lévyne-Ca, refined from powder X-ray data, are a 13.330(3), c 23.0122(3) Å and V 3541.3(9) Å3. Its empirical formula is Ca2.76K0.68Na0.17Sr0.02(Si14.46Al6.36) O36·18H2O. Erionite-Ca forms white epitaxial aggregates on the surface (0001) of lévyne-Ca crystals. These aggregates are composed of fine needles oriented perpendicular to the surface of lévyne-Ca. Its chemical analyses correspond to the empirical formula Ca2.76K0.68Na0.17Sr0.02(Si14.46Al6.36)O36·18H2O. Gismondine, the rarest mineral found at this site, forms typical colorless to whitish dipyramidal crystals with size up to 1 mm. The unit cell parameters of gismondine, refined from powder X-ray data, are a 10.021(2), b 10.630(3), c 9.828(3) Å, β 92.51° and V 1045.8(5) Å3. Chemical analyses of gismondine correspond to the empirical formula Ca1.98Na0.06(Si4.10Al3.85)O16·8H2O. Thomsonite-Ca forms colorless to yellowish tabular crystals and hemispherical aggregates. The unit cell parameters of thomsonite-Ca, refined from powder X-ray data are a 13.104(2), b 13.056(1), c 13.247(2) Å and V 2266.4(6) Å3. The empirical formula of thomsonite-Ca can be expressed as Ca1.78Sr0.05Na1.12(Al4.69Si5.29)O20·6H2O. Phillipsite-K forms typical columnar colorless to whitish crystals with a size 1 - 2 mm. The unit cell parameters of phillipsite-K, refined from powder X-ray data, are a 9.917(4), b 14.314(8), c 8.737(4) Å, β 124.920° and V 1016.9(9) Å3. Chemical analyses of phillipsite-K correspond to the empirical formula K1.95Ca1.91Na0.12(Si10.09Al5.91)O32·12H2O. Chabazite-Ca forms colorless glassy rhombohedron. The unit cell parameters of chabazite-Ca, refined from powder X-ray data, are a 13.837(6), c 15.0073(4) Å and V 2488(1) Å3. Its empirical formula is Ca1.54Na0.20K0.14Sr0.04(Al3.46Si8.53)O24·13H2O. Natrolite forms whitish needles and hemispheres of up to 1 cm, which fill in cavities up to 5 cm. The unit cell parameters of natrolite, refined from powder X-ray data are a 18.376(5), b 18.552(5), c 6.585(2) Å and V 2244(1) Å3. The empirical formula can be expressed as Na1.79Ca0.10 (Si3.01Al1.99)O10·2H2O. Analcime occurs in the cavities together with larger hemispheres of cowlesite and lévyne-Ca and it forms whitish lenticular crystals. The unit cell parameters of analcime, refined from powder X-ray data are a 13.703(5) Å and V 573(1) Å3. Chemical analyses of analcime correspond to the empirical formula Na0.90K0.01(Al0.93Si2.07)O6·H2O.

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