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Strontium Dependence of the Lattice Constants of Barites from the Kreševo Area in Central Bosnia (Bosnia and Herzegovina)

The lattice constants of a synthetic BaSO4 and fourteen natural barite samples from the Kreševo area (Central Bosnia) were determined by X-ray powder diffraction. The natural samples contained from 0.3&#65533; 17.6 mole % SrSO4, and negligible concentrations of Ca and Pb (<0.03 and 0.02 wt. %, respectively), thus representing almost pure (Ba, Sr)SO4 solid solutions. The diffraction lines of most natural samples were broadenrd in relation to those of synthetic BaSO4. This results from obvious compositional heterogeneity, e.g. the heterogeneous distribution of strontium, as is clearly observed from Sr variation patterns across a surface of the barite obtained by proton microprobe analysis. Nevertheless, the present values of unit-cell parameters are in agreement with those of synthetic (Ba, Sr)SO4 solid solutions documented in the literature. It has been proven that the interplanar spacing d004 may be used for determination of the Sr content of natural barites ; the absolute error varies from ą0.3 mole % SrSO4 (for homogeneous samples having the diffraction line 004 clearly resolved in spectral doublet components) up to ą0.5 mole % SrSO4 (for the smaples with compositional heterogeneity having a broadened and relative poorly defined diffraction line 004).

Strontium bearing barites; Lattice constants; Inhomogeneous strontium distribution in barite; XRD determination of Sr in barite; Kreševo; Central Bosnia

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