TY - JOUR

T1 - Embreyite

T2 - Structure determination, chemical formula and comparative crystal chemistry

AU - Kovrugin, Vadim M.

AU - Siidra, Oleg I.

AU - Pekov, Igor V.

AU - Chukanov, Nikita V.

AU - Khanin, Dmitry A.

AU - Agakhanov, Atali A.

PY - 2018/4/1

Y1 - 2018/4/1

N2 - Embreyite from the Berezovskoe, Urals, Russia, was studied by the means of powder X-ray diffraction (XRD), single-crystal XRD, infrared spectroscopy and microprobe analysis. The empirical formula of embreyite obtained on the basis of micmpmbe analysis is Pb1.29Cu0.07Cr0.52P0.43O4 (without taking into account the presence of 11,0). An examination of single-crystal XRD frames of the tested crystals cut from embreyite intergrowths revealed split reflection spots of weak intensities, even after a long exposure time. The crystal structure of embreyite (monoclinic, C2/m, a = 9.802(16), b = 5.603(9), c = 7.649(12) . beta = 114.85(3)degrees and V=381.2(11)(3)) has been solved by direct methods and re fined to R-1 = 0.050 for 318 unique observed reflections. The powder XRD patterns of the holotype embreyite and the fresh material studied are close in both dvalues and the intensities match the pattern calculated from the structural single-crystal XRD data. The unit-cell parameters were recalculated for the holotype sample using anew cell setting and corresponding hkl indices. The crystal structure of embreyite is based on layers formed by corner-sharing mixed chromate-phosphate tetrahedra and PbO6 distorted octahedra. The interlayer space is filled by disordered Pb2+ and Cu2+ cations. Generally, the crystal structure of embreyite can be referred to the structural type of palmierite. {Pb[(Cr,P)O-4](2)} layers in embreyite are similar in topology to those in yavapaiite-type compounds. The general formula of embreyite can be represented as (PbxMy2+square(1 x) y)(2){Pb[Cr,P)O-4](2)}(H2O)(n), where M2+ =Cu and Zn and 0.5

AB - Embreyite from the Berezovskoe, Urals, Russia, was studied by the means of powder X-ray diffraction (XRD), single-crystal XRD, infrared spectroscopy and microprobe analysis. The empirical formula of embreyite obtained on the basis of micmpmbe analysis is Pb1.29Cu0.07Cr0.52P0.43O4 (without taking into account the presence of 11,0). An examination of single-crystal XRD frames of the tested crystals cut from embreyite intergrowths revealed split reflection spots of weak intensities, even after a long exposure time. The crystal structure of embreyite (monoclinic, C2/m, a = 9.802(16), b = 5.603(9), c = 7.649(12) . beta = 114.85(3)degrees and V=381.2(11)(3)) has been solved by direct methods and re fined to R-1 = 0.050 for 318 unique observed reflections. The powder XRD patterns of the holotype embreyite and the fresh material studied are close in both dvalues and the intensities match the pattern calculated from the structural single-crystal XRD data. The unit-cell parameters were recalculated for the holotype sample using anew cell setting and corresponding hkl indices. The crystal structure of embreyite is based on layers formed by corner-sharing mixed chromate-phosphate tetrahedra and PbO6 distorted octahedra. The interlayer space is filled by disordered Pb2+ and Cu2+ cations. Generally, the crystal structure of embreyite can be referred to the structural type of palmierite. {Pb[(Cr,P)O-4](2)} layers in embreyite are similar in topology to those in yavapaiite-type compounds. The general formula of embreyite can be represented as (PbxMy2+square(1 x) y)(2){Pb[Cr,P)O-4](2)}(H2O)(n), where M2+ =Cu and Zn and 0.5

KW - Berezovskoe deposit

KW - Cassedanneite

KW - Chromate

KW - Embreyite

KW - Layered structure

KW - Lead

KW - Oxidation zone

KW - Phosphate

KW - Urals

KW - Vauquelinite

KW - oxidation zone

KW - KAMCHATKA

KW - PHOENICOCHROITE

KW - FORNACITE

KW - chromate

KW - PHASE-TRANSFORMATION

KW - vauquelinite

KW - TOLBACHIK VOLCANO

KW - HEMIHEDRITE

KW - phosphate

KW - cassedarmeite

KW - lead

KW - REFINEMENT

KW - CALIFORNIA

KW - layered structure

KW - X-RAY

KW - embreyite

KW - CHROMATE

UR - http://www.scopus.com/inward/record.url?scp=85051220994&partnerID=8YFLogxK

UR - https://www.cambridge.org/core/product/identifier/S0026461X18000348/type/journal_article

UR - http://www.mendeley.com/research/embreyite-structure-determination-chemical-formula-comparative-crystal-chemistry

U2 - 10.1180/minmag.2017.081.041

DO - 10.1180/minmag.2017.081.041

M3 - Article

AN - SCOPUS:85051220994

VL - 82

SP - 275

EP - 290

JO - Mineralogical Magazine

JF - Mineralogical Magazine

SN - 0026-461X

IS - 2

ER -