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Universita di Modena, Dipartimento di Scienze della Terra, Modena, Italy
A Ba-rich celestine (Sr (sub 0.87) Ba (sub 0.13) SO 4 ) filling cavities of volcanoclastic rocks from Montecchio Maggiore (Vicenza, Italy) was studied. The role of the Ba content in the mineral was determined using X-ray powder data, single crystal X-ray refinement, thermal and chemical analyses. The unit cell parameters (obtained by single crystal diffraction) are a = 8.408, b = 5.372, c = 6.897 Aa. and the refinement in the space group Pnma (Z = 4) gives the final R value of 0.039. The average (Sr,Ba)-oxygen bond length is 2.842 Aa and agrees with an occupancy of Sr 87% and Ba 13%. Individual bond lengths (Sr,Ba)-O and bond strength calculations confirm that all twelve interactions are significant and define an irregular array around the cation.
This record provided courtesy of AGI/GeoRef.
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  R. W. Luth and M. Bowerman MICROTEXTURAL AND POWDER-DIFFRACTION STUDY OF ANALCIME PHENOCRYSTS IN VOLCANIC ROCKS OF THE CROWSNEST FORMATION, SOUTHERN ALBERTA, CANADA Can Mineral, June 1, 2004; 42(3): 897 - 903. [Abstract] [Full Text] [PDF]
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