Klebelsbergite, Sb4O4SO4(OH)2

stability relationships, formation in Nature, and refinement of its structure

Adam J. Roper, Peter Leverett, Timothy D. Murphy, Peter A. Williams*, David E. Hibbs

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The extent to which secondary Sb minerals control Sb dispersion in the supergene environment is yet to be fully understood. Stability studies of klebelsbergite have been undertaken to better under-stand its role in controlling Sb mobility and relationships with other secondary Sb minerals. Solubility in aqueous 0.1084 M HNO3 was determined at 298.15 K and the data obtained used to derive Gfθ(klebelsbergite, s, 298.15 K) =-2056.4 ± 5.0 kJ/mol. Solubility data have been used to deduce the conditions under which the mineral can form as a thermodynamically stable phase. The single-crystal X-ray structure of synthetic klebelsbergite has been determined 293 K and is essentially the same as that reported earlier for atoms with Z ≥ 8. Crystal data: orthorhombic, space group Pca21, a = 5.7563(4), b = 11.2538(7), c = 14.8627(9) Å, V = 962.81(11) Å3, Z = 4. Refinement converged to R1 = 0.0154 for 2206 unique reflections with I > 2σ(I). The present study has located the hydroxyl H atoms on both O5 and O9. The H-bond arrangements are somewhat different to those proposed earlier with the quasi-linear O9-H···O3 interaction having <(DHA) = 171(6)°. The O5 hydroxyl H atom lies in a different position to that proposed earlier and is involved in a bifurcated H-bond arrangement with O2 and with itself in a symmetry-related position, with <(DHA) = 133(5) and 125(5)°, respectively.

Original languageEnglish
Pages (from-to)602-607
Number of pages6
JournalAmerican Mineralogist
Volume100
Issue number2-3
DOIs
Publication statusPublished - 1 Feb 2015
Externally publishedYes

Keywords

  • Klebelsbergite
  • antimony
  • antimony sulfate
  • solubility
  • stability
  • structure
  • hydrogen bonding

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