Publication Date:
2017-02-03
Description:
The crystal structures of isomertieite, Pd 11 Sb 2 As 2 , (I) from the Monche-Tundra intrusion, Monchegorsk Igneous Complex (MIC), Kola Peninsula, Russia, and törnroosite, Pd 11 As 2 (Te 1.7 Bi 0.3 ) 2 (IIa) and Pd 11 As 2 (Te 1.3 Bi 0.7 ) 2 (IIb) from the South Sopcha intrusion, MIC, Kola Peninsula, Russia, were refined on the basis of X-ray diffraction data collected from single crystals. The two minerals were found to exhibit the same structure, cubic, space group Fd m , Z = 8, with unit-cell parameters for (I): a 12.297(5) Å, V 1859.3(2) Å 3 ; for (IIa): a 12.350(2) Å, V 1883.6(4) Å 3 ; and for (IIb): a 12.370(1) Å, V 1892.9(3) Å 3 . The structures were refined to R 1 = 0.056 (I), 0.014 (IIa), 0.018 (IIb). The isomertieite crystal-chemical formula was confirmed. The Bi-for-Te substitution in törnroosite was found to not affect the main structural topology. In the structure of the two minerals there are three symmetrically independent Pd positions: M 1, M 2, and M 3. M 1 forms M 1As 4 tetrahedra, M 2 forms M 2As 2 Sb 2 (I) or M 2As 2 Te 2 (II) tetrahedra, and M 3 forms M 3Sb 3 (I) or M 3Te 3 (II) triangles connected together via common edges and forming a framework in the structure.
Print ISSN:
0008-4476
Topics:
Geosciences
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