P. Voudouris

Pb2(AsO2OH)Cl2, a new phase from the Lavrion ancient slags, Greece: occurrence and characterization

Abstract Transparent prismatic crystals of Pb2(AsO2OH)Cl2 were collected in black metallurgical slag on the coast in the Punta Zeza area, 3 km south of the town of Lavrion, Greece. Analyses by energy-dispersive X-ray spectrometry (EDS) provided the following chemical composition: PbO 73.04, As2O3 15.97, Cl 11.42, O=Cl -2.58, total 97.85 wt.%. The empirical formula calculated on the basis of As = 1 is HxPb2.03(AsO3)1.00Cl1.995 (x = 0.96). The infrared spectrum of Pb2(AsO2OH)Cl2 has characteristic AsO33- bands at 707 and 594 cm-1, O-H stretching vibrations at 3310 and 2900 cm-1 and a band at 1107 cm-1 which is assigned to As-O-H bending vibrations. The structure, which is monoclinic P21/m, a = 6.4235(8), b = 5.5399(7), c = 9.321(1) Å, β = 90.767(2)°, V = 331.67(7) Å3, R1 = 0.035, is identical to that of synthetic Pb2(AsO2OH)Cl2 and contains two symmetrically unique Pb sites and one As site. The crystal structure is based on [Pb2AsO2OH]2+ double chains interconnected via weak Pb-Cl bonds to produce a three-dimensional framework which is closely related to that of Pb oxysalt minerals containing [O2Pb3]2+ chains of oxocentred [OPb4]6+ tetrahedra including mendipite, damaraite, rickturnerite and plumboselite.

Hilarionite, Fe23+(SO4)(AsO4)(OH) · 6H2O, a new supergene mineral from Lavrion, Greece

A new mineral, hilarionite, ideally Fe23+ (SO4)(AsO4)(OH) · 6H2O, has been found in the Hilarion Mine, Agios Konstantinos, Kamariza, Lavrion district, Attiki Prefecture, Greece. It was formed in the oxidation zone of a sulfide-rich orebody in association with goethite, gypsum, bukovskyite, jarosite, melanterite, chalcanthite, allophane, and azurite. Hilarionite occurs as light green (typically with an olive or grayish tint) to light yellowish green spherulites (up to 1 mm in size) and bunches of prismatic to acicular “individuals” up to 0.5 mm long that are in fact near-parallel or divergent aggregates of very thin, curved fibers up to 0.3 mm long and usually lesser than 2 μm thick. The luster is silky to vitreous. The Mohs’ hardness is ca. 2. Hilarionite is ductile, its “individuals” are flexible and inelastic; fracture is uneven or splintery. D(meas) = 2.40(5), D(calc) = 2.486 g/cm3. IR spectrum shows the presence of arsenate and sulfate groups and H2O molecules in significant amounts. The Mössbauer spectrum indicates the presence of Fe3+ at two six-fold coordinated sites and the absence of Fe2+. Hilarionite is optically biaxial (+), α = 1.575(2), γ = 1.64(2), 2V is large. The chemical composition (electron microprobe, average of 7 point analyses; H2O determined by modified Penfield method) is as follows, wt %: 0.03 MnO, 0.18 CuO, 0.17 ZnO, 33.83 Fe2O3, 0.22 P2O5, 18.92 As2O5, 22.19 SO3, 26.3 H2O, total is 101.82%. The empirical formula calculated on the basis of 15 O is: (Fe1.903+Cu0.01Zn0.01)Σ1.92[(SO4)1.24(AsO4)0.74(PO4)0.01]Σ1.99(OH)1.01 · 6.03H2O. The X-ray powder diffraction data show close structural relationship of hilarionite and kaňkite, Fe23+(AsO4)2 · 7H2O. Hilarionite is monoclinic, space group C2/m, Cm or C2, a = 18.53(4), b = 17.43(3), c = 7.56(1) Å, β = 94.06(15)°, V = 2436(3) Å3, Z = 8. The strongest reflections in the X-ray powder diffraction pattern (d, Å-I[hkl]) are: 12.66–100[110],

Mineralogy of telluride-bearing epithermal ores in the Kassiteres-Sappes area, western Thrace, Greece

7.60 - 6[00bar 1]

Mineralogy and geochemical environment of formation of the Perama Hill high-sulfidation epithermal Au-Ag-Te-Se deposit, Petrota Graben, NE Greece

, 5.00–10[22l],

A cervelleite-like mineral and other Ag-Cu-Te-S minerals [Ag2CuTeS and (Ag,Cu)2TeS] in gold-bearing veins in metamorphic rocks of the Cycladic Blueschist Unit, Kallianou, Evia Island, Greece

4.70 - 10[31bar 1]

Sn-Bearing Minerals and Associated Sphalerite from Lead-Zinc Deposits, Kosovo: An Electron Microprobe and LA-ICP-MS Study

, 4.33–7[040]. Hilarionite is named after its type locality.