Crystal chemistry of a Ni-Mg-analogue of lyonsite from slags of Lavrion, Greece
Koshlyakova, Natalia N.; Zubkova, Natalia V.; Pekov, Igor V.; Giester, Gerald; Pushcharovsky, Dmitry Yu.; Chukanov, Nikita V.; Voudouris, Panagiotis; Magganas, Andreas; Katerinopoulos, Athanassios
published: Apr 1, 2016
ArtNo. ESP154019302000, Price: 29.00 €
A novel Ni-Mg-analogue of lyonsite, Cu3 + x (Fe3+4-2xCu2x )(VO4)6(0 ≤ x ≤1), with substitution of Ni and Mg for Cu (below: NMAL) was found in old metallurgical slags from the historical Lavrion mining district in Greece. NMAL forms reddish- black, with semimetallic lustre, prismatic to acicular crystals up to 1 mm long and up to 0.2 mm thick and is associated with anthropogenic counterparts of liebenbergite, trevorite, schäferite, bannermanite, albite, nosean, haüyne and others. The crystal structure of NMAL was solved from single-crystal X-ray diffraction data (298 K), R = 0.0238. NMAL is orthorhombic, Pnma, a = 4.9573(3), b = 10.1672(8), c = 17.1605(12) Å, V = 864.92(11) Å3. Its chemical composition, determined by electron microprobe, is: MgO 5.71, NiO 19.62, ZnO 0.84, Al2 O3 0.84, Mn2 O3 0.24, Fe2 O3 18.43, SiO2 0.06, TiO2 1.82, P2 O5 0.38, V2 O5 51.77, total 99.72 wt.%. The formula derived from both the crystal structure and electron microprobe data is (Z = 2):A(1) (Fe3+ 2.48Ni1.28Ti 0.12Al0.12)Σ4 A(2) (Mg1.22 Ni0.44 Zn0.10)Σ1.76 A(2') (Mg0.16 Ni0.06 Zn0.02)Σ0.24 A(3) (Ni0.54 Ti0.08 Al0.02 0.28)Σ0.92 A(3') (Ni0.62 Ti0.08 Al0.04 0.34)Σ1.08 (VO4)6 (calculated on the basis of 24 O atoms). The bulk formula of NMAL is (Ni2.94 Fe3+ 2.48Mg1.38Ti0.28Al 0.18Zn0.12 0.62) Σ8(VO4)6and the simplified crystal-chemical formula is (Ni,)2(Mg, Ni)2(Fe3+, Ni)4(VO 4)6.