Titre du document / Document title

Structural reinvestigation of getchellite As^0.09Sb^1.02S^3.00

Auteur(s) / Author(s)

KYONO Atsushi ; KIMATA Mitsuyoshi ;

Résumé / Abstract

The crystal structure of getchellite, As^0.98Sb^1.02S^3.00, from the type-locality (the Getchell mine, Humboldt County, Nevada), monoclinic, P2¹/a, a = 11.949(3), b = 9.028(1), c = 10.130(2) Å, β = 116.15(1)°,V = 980.9(4) Å₃, Z = 8, was solved by direct methods and refined with full-matrix least-squares techniques to R = 0.058 and Rw = 0.062 for 505 observed reflections [I^o > 5σ(I^o)] collected using MoKa radiation. The structure is made up of (As,Sb)S³ trigonal pyramids forming an eight-membered (As,Sb)⁸S⁸ ring; the sheets formed by the eight-membered rings are connected to each other by Sl and S6 atoms are parallel to (001). The sheet structure is responsible for the cleavage and twin planes of getchellite. The cations predominantly occupy the M2 site in natural getchellite, because the M2S⁶ polyhedron has the most distorted (irregular) geometry compared with other metal polyhedra in the structure. The amount of As incorporated at the M1 sites correlates strongly with M2 site composition. An important feature of As₃₊ sulfide minerals is that the crystal structures are composed of a 3-dimensional network consisting not only of AsS³ pyramids but also containing trigonal pyramids of other constituent cations because the structures are governed strongly by the stereochemical requirement of As₃₊cations for MS³ trigonal pyramids.

Revue / Journal Title

The American mineralogist   ISSN 0003-004X   CODEN AMMIAY 

Source / Source

2004, vol. 89, n^o5-6, pp. 696-700 [5 page(s) (article)]

Langue / Language

Anglais

Editeur / Publisher

Mineralogical Society of America, Washington, DC, ETATS-UNIS  (1916) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 503, 35400011198794.0030