Ba-rich Celestine: New Data and Crystal Structure Refinement

M. F. Brigatti, E. Galli and L. Medici
Dipartimento di Scienze della Terra, Università di Modena, Largo S. Eufemia 19, I-41100, Modena, Italy

Abstract: A Ba-rich celestine (Sr0.87Ba0.13SO4) 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 Å, 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 Å 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.

Keywords: celestine • barium • crystal structure refinement • Vicenza • Italy

Mineralogical Magazine; June 1997 v. 61; no. 406; p. 447-451; DOI: 10.1180/minmag.1997.061.406.10
© 1997, The Mineralogical Society
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