Publication Date:
2015-02-01
Description:
The crystal structure of a specimen of `Pb-rich' chabournéite from Jas Roux, Hautes-Alpes, France, with the chemical formula obtained by electron microprobe analysis of Ag0.04 (1)Tl2.15 (2)Pb0.64 (1)Sb5.12 (1)As5.05 (1)S17.32 (5), has been solved by X-ray single-crystal diffraction on the basis of 36 550 observed reflections (withFo〉 4σFo) with a finalR1= 0.074. Pb-rich chabournéite is triclinicP1, with unit-cell parametersa= 8.5197 (4),b= 42.461 (2),c= 16.293 (8) Å, α = 83.351 (2), β = 90.958 (2), γ = 84.275 (2)°,V= 5823 (3) Å3. Its structural formula is close to [Tl2(Pb0.8Tl0.1Sb1.1)](Sb4.1As4.9)S17, withZ= 8. Its crystal structure is formed by the alternation of two pairs of slabs along thebaxis, deriving from the SnS and PbS archetypes, respectively. 104 independent cation sites and 136 S sites occur in the unit cell. Slab interfaces show the alternation, alongc, of Tl sites, ninefold coordinated, with Pb, Sb or mixed/split (Pb,Sb) and (Pb,Tl) sites. Within the slabs, 72 independentM3+sites (M3+= As, Sb) occur. ConsideringM3+—S bond distances shorter than 2.70 Å,MS3triangular pyramidal groups are condensed according to variousMmSnchain fragments (`polymers'). The solution of the crystal structure of chabournéite allows its comparison with the closely related homeotypes protochabournéite and dalnegroite.
Print ISSN:
2052-5192
Electronic ISSN:
2052-5206
Topics:
Chemistry and Pharmacology
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Geosciences
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Physics
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