Simultaneous refinement of two components of an exsolution intergrowth: crystal structures of the lindstromite-krupkaite pair

TY - JOUR

T1 - Simultaneous refinement of two components of an exsolution intergrowth

T2 - crystal structures of the lindstromite-krupkaite pair

AU - Topa, Dan

AU - Petricek, Vaclav

AU - Dusek, Michal

AU - Makovicky, Emil

AU - Balic Zunic, Tonci

PY - 2008

Y1 - 2008

N2 - Crystal structures of intergrown lindstromite and krupkaite were determined in two distinct samples by a simultaneous crystal-structure refinement using a modified JANA program package. The exsolution intergrowths have a bulk composition, determined by means of electron microprobe, equal to bd(60.1) and bd(64.1), respectively. The subscript indicates a percentage of the aikinite component in this bismuthinite derivative. The crystal Structure of lindstromite contains two aikinite-like ribbons Cu2Pb2Bi3S6 and eight krupkaite-like ribbons (ideally CuPbBi3S6) in a unit cell. The latter are oversubstituted; the ideally empty tetrahedral sites associated with them refined to the occupancy values of 0.04-0.09 Cu and 0.14-0.18 Cu, respectively, for the two above bulk compositions. The refined phase-compositions are Cu6.26Pb6.26Bi13.74S30 (bd(62.6)) associated with CuPbBi3S6 (bd(50)) for the sample 'bd(60)' and Cu6.64Pb6.64Bi13.36S30 (bd(66.4)) associated with oversubstituted krupkaite, the composition of which could not been refined, for the sample 'bd(64)'. From stoichiometry calculations, the latter is similar to bd(60). Both latter values may be somewhat overestimated as a result of cross-correlations between the two closely related structures during the refinement.

AB - Crystal structures of intergrown lindstromite and krupkaite were determined in two distinct samples by a simultaneous crystal-structure refinement using a modified JANA program package. The exsolution intergrowths have a bulk composition, determined by means of electron microprobe, equal to bd(60.1) and bd(64.1), respectively. The subscript indicates a percentage of the aikinite component in this bismuthinite derivative. The crystal Structure of lindstromite contains two aikinite-like ribbons Cu2Pb2Bi3S6 and eight krupkaite-like ribbons (ideally CuPbBi3S6) in a unit cell. The latter are oversubstituted; the ideally empty tetrahedral sites associated with them refined to the occupancy values of 0.04-0.09 Cu and 0.14-0.18 Cu, respectively, for the two above bulk compositions. The refined phase-compositions are Cu6.26Pb6.26Bi13.74S30 (bd(62.6)) associated with CuPbBi3S6 (bd(50)) for the sample 'bd(60)' and Cu6.64Pb6.64Bi13.36S30 (bd(66.4)) associated with oversubstituted krupkaite, the composition of which could not been refined, for the sample 'bd(64)'. From stoichiometry calculations, the latter is similar to bd(60). Both latter values may be somewhat overestimated as a result of cross-correlations between the two closely related structures during the refinement.

KW - Faculty of Science

KW - lindstromite

KW - oversubstitution; bismuthinite-aikinite series

KW - Simultaneous structure refinement

KW - crystal structure

KW - krupkaite

U2 - 10.3749/canmin.46.2.525

DO - 10.3749/canmin.46.2.525

M3 - Journal article

SN - 0008-4476

VL - 46

SP - 525

EP - 539

JO - Canadian Mineralogist

JF - Canadian Mineralogist

IS - 2

ER -