What is the reason for the doubled unit-cell volumes of copper-lead-rich pavonite homologues? the crystal structures of cupromakovickyite and makovickyite

TY - JOUR

T1 - What is the reason for the doubled unit-cell volumes of copper-lead-rich pavonite homologues?

T2 - the crystal structures of cupromakovickyite and makovickyite

AU - Topa, Dan

AU - Makovicky, Emil

AU - Balic Zunic, Tonci

PY - 2008

Y1 - 2008

N2 - The crystal Structure of cupromakovickyite, ideally Cu8Pb4Ag2Bi18S36, from the skarn deposit at Baita Bihor, in Romania, has been solved by direct methods and refined to an RI index of 5.36% for 2680 unique reflections measured with MOKU radiation oil it four-circle diffractometer equipped with a CCD detector. Cupromakovickyite has a monoclinic cell with a 13.405(8), b 4.016(3), c 29.949(19) angstrom, beta 99.989(16), V 1587.8(17) angstrom(3), space group C2/m and Z = 1. There are eight metal sites and twelve Sulfur sites in each of the four asymmetric units. The thicker, galena-like layers are composed of parallel chains Bi4-Bi1-Bi1-Bi4 four octahedra long. In the thinner layers, the octahedra of Ag are replaced by two tetrahedrally coordinated Cu sites, whereas one of the paired Square pyramids of Bi is replaced by Pb. The asymmetry of the thin layer is responsible for the doubling of the c parameter for cupromakovickyite with respect to makovickyite. To be able to compare them, the crystal structure of Cu-bearing makovickyite, Cu2.25Ag1.56 (Pb0.27Cd0.13)(Sigma 0.4)Bi10.46S18, from a scheelite deposit at Felbertal, in Austria, has been refined to in R, index of 4.36% for 1320 unique reflections measured with the same equipment. Makovickyite has a monoclinic cell with a 13.239(3), b 4.0547(7), c 14.667(3) angstrom, beta 99.397(4), V 776.7(3) angstrom(3), space group C2/m and Z = 1. There are four metal sites and six sulfur sites in each Of the four asymmetric units. The thicker, galena-like layers are composed of parallel chains Bi2-Bi1-Bi1-Bi2 four octahedra long. In the thinner layers, the octahedra of Ag are partially replaced by two tetrahedrally coordinated Cu sites.

AB - The crystal Structure of cupromakovickyite, ideally Cu8Pb4Ag2Bi18S36, from the skarn deposit at Baita Bihor, in Romania, has been solved by direct methods and refined to an RI index of 5.36% for 2680 unique reflections measured with MOKU radiation oil it four-circle diffractometer equipped with a CCD detector. Cupromakovickyite has a monoclinic cell with a 13.405(8), b 4.016(3), c 29.949(19) angstrom, beta 99.989(16), V 1587.8(17) angstrom(3), space group C2/m and Z = 1. There are eight metal sites and twelve Sulfur sites in each of the four asymmetric units. The thicker, galena-like layers are composed of parallel chains Bi4-Bi1-Bi1-Bi4 four octahedra long. In the thinner layers, the octahedra of Ag are replaced by two tetrahedrally coordinated Cu sites, whereas one of the paired Square pyramids of Bi is replaced by Pb. The asymmetry of the thin layer is responsible for the doubling of the c parameter for cupromakovickyite with respect to makovickyite. To be able to compare them, the crystal structure of Cu-bearing makovickyite, Cu2.25Ag1.56 (Pb0.27Cd0.13)(Sigma 0.4)Bi10.46S18, from a scheelite deposit at Felbertal, in Austria, has been refined to in R, index of 4.36% for 1320 unique reflections measured with the same equipment. Makovickyite has a monoclinic cell with a 13.239(3), b 4.0547(7), c 14.667(3) angstrom, beta 99.397(4), V 776.7(3) angstrom(3), space group C2/m and Z = 1. There are four metal sites and six sulfur sites in each Of the four asymmetric units. The thicker, galena-like layers are composed of parallel chains Bi2-Bi1-Bi1-Bi2 four octahedra long. In the thinner layers, the octahedra of Ag are partially replaced by two tetrahedrally coordinated Cu sites.

KW - Faculty of Science

KW - cupromakovickyite

KW - Austria

KW - Felbertal

KW - Romania

KW - Baita Bihor

KW - pavonite homologous series

KW - crystal structure

KW - single-crystal X-ray diffraction

KW - sulfosalt

KW - cupropavonite

KW - makovickyite

U2 - 10.3749/canmin.46.2.515

DO - 10.3749/canmin.46.2.515

M3 - Journal article

SN - 0008-4476

VL - 46

SP - 515

EP - 523

JO - Canadian Mineralogist

JF - Canadian Mineralogist

IS - 2

ER -