Original paper

Crystal structure of synthetic Pb12.65Sb11.35S28.35Cl2.65 - A new view of the crystal chemistry of chlorine-bearing lead-antimony sulphosalts

Kostov, Vladislav V.; Macicek, Jοsef

European Journal of Mineralogy Volume 7 Number 4 (1995), p. 1007 - 1018

29 references

published: Aug 1, 1995
manuscript accepted: Mar 7, 1995
manuscript received: Jul 20, 1994

DOI: 10.1127/ejm/7/4/1007

BibTeX file

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Abstract

Abstract The structure of a new synthetic chlorine sulphosalt - Pb10+xSb14-xS31-xClx, x = 2.65, is determined by X-ray structure analysis using site-occupancy refinement and bond-valence method. Microprobe analyses give: Pb - 52.7, Sb - 28.2, S - 18.1, Cl - 1.9 wt%. The crystals are prepared at 420°C by dry synthesis. Reflectance data (Rmax and Rmin between 400 and 700nm) decrease regularly from 40.5-36.1 to 30.8-29.5%. Powder data: monoclinic I - lattice, a = 19.512(12), b = 4.052(3), c = 35.134(17) Å, ß = 96.34(5)°, V = 2761(3) Å3. Single crystal investigations establish the space group as 121 m, with a = 19.502(1), b = 4.049(1), c = 35.115(1) Å, ß = 96.32(1)°, V = 2756(1) Å3, Z = 2, F.W. = 5007.5, Dx = 6.032 gem-3, and R = 0.033 for 1978 observed reflections with I > 3 σ (I). The crystal structure is closely related to that of dadsonite. Application of the bond-valence method shows that the special position 1/2, 1/2, 0 is entirely occupied by chlorine. Other chlorine atoms partially substitute on specific sulphur positions, in connection with mixed (Pb, Sb) sites. The major Cl content is due to this second substitution rule, and may play a fundamental role in the crystal chemistry of Cl-rich lead antimony sulphosalts.

Keywords

lead-antimony chlorine sulphosaltcrystal structurebond-valence methoddadsonite series