• journal_title：The Canadian Mineralogist
• Contributor：Dan Topa ; Emil Makovicky ; Herman J. Schimper ; Herbert Dittrich
• Publisher：Mineralogical Association of Canada
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.3749/canmin.48.5.1127
• journal_abbrev：Can Mineral
• issn：0008-4476
• volume：48
• issue：5
• firstpage：1127
• section：Articles

The new compound, ideally Ag<sub>2.25sub>Pb<sub>2.5sub>Bi<sub>4.25sub>S<sub>10sub>, has been synthesized at 850°C by reacting simple sulfides of Bi, Pb and Ag. It crystallizes in the orthorhombic system, space group Cmcm, with a 4.084(1), b 13.453(4), c 33.932(9) Å, V 1864.4(9) Å<sup>3sup> and Z = 4. The crystal structure has been refined to R<sub>1sub> = 3.66% for 1132 unique [F<sub>osub> > 4σ(F<sub>osub>)] reflections collected on a Bruker single-crystal diffractometer with a CCD detector and monochromated MoKα X-radiation. The structure contains one Pb site with a trigonal prismatic coordination, positioned on the reflection planes of the space group, four distinct octahedral sites, of which one is a mixed (Pb,Ag) site and two are (Bi,Ag) sites, and six anion sites. The new compound is the member number N<sub>1,2sub> = 8,8 of the lillianite homologous series. It is the homologue of lillianite richest in silver known to date. The present synthesis and investigation of the lillianite homologue <sup>8,8sup>L allow us to contribute a new structural interpretation for the silver-rich portions of the system Pb–Bi–Ag–S. The existence of Ag-rich phases with N = 8 is caused by a viability of ordered slabs of Ag–Bi–Pb octahedra in the homologues that have favorable Ag:Bi:Pb proportions.