title: On the symmetry of wulfenite (Pb[MoO4]) from Meǽica (Slovenia).
abstract: Wulfenite [lead(II) molybdate(VI)] is known as a scheelite structure in the I4(1)/a space group. The structure of the unusual `hemimorphic' wulfenite crystals from the Meǽica mine was refined in the noncentrosymmetric space group I ̅4 using a Pb/Mo exchange disorder model with the approximate composition Pb(0.94)Mo(0.06)[MoO(4)]. Pb atoms in the 2b positions are substituted by Mo at about 12%. The crystal is shown to be twinned by inversion. Hemimorphism may result from the short-range chemical ordering of the metal atoms at the 2b positions.
authors.affiliation: Department of Mineralogy, Eötvös Loránd University, Pázmány P. stny. 1/c, 1117 Budapest, Hungary. coraildiko@gmail.com
authors.forename: Ildikó
authors.initials: I
authors.lastname: Cora
authors.forename: Mátyás
authors.initials: M
authors.lastname: Czugler
authors.forename: István
authors.initials: I
authors.lastname: Dódony
authors.forename: Aleksander
authors.initials: A
authors.lastname: Rečnik