• journal_title：The Canadian Mineralogist
• Contributor：Sergey V. Krivovichev ; Lidiya P. Vergasova ; Sergey N. Britvin ; Stanislav K. Filatov ; Volker Kahlenberg ; Vladimir V. Ananiev
• Publisher：Mineralogical Association of Canada
• Date：2007-
• Format：text/html
• Language：en
• Identifier：10.2113/gscanmin.45.4.921
• journal_abbrev：Can Mineral
• issn：0008-4476
• volume：45
• issue：4
• firstpage：921
• section：Articles

Pauflerite, β-VO(SO₄), is a new mineral species from the fumaroles of the Great Fissure Tolbachik eruption (GFTE), Kamchatka Peninsula, Russia. It was found in 1977 in the first cinder cone of the North breach of the GFTE. The mineral occurs as light green prismatic crystals up to 0.1 mm in length, associated with shcherbinaite (V₂O₅), an unknown Tl–Bi sulfate and finely crystalline Mg, Al, Fe and Na sulfates. Pauflerite is light green with a white streak and vitreous luster; the mineral is transparent and non-fluorescent. The Mohs hardness is 3–4. Pauflerite is brittle, and without visible cleavage. The density is 3.36(4) (measured) and 3.294 g/cm³ (calculated). The mineral is biaxial, optically positive, α 1.731(4), β 1.778(2), γ 1.845(4), with 2V_meas ≈ 90°, and 2V_calc equal to 83°. The orientation was determined as X = a; further details are unclear. Pleochroism is clear in green tones: X light green, Y bluish green, Z light green-blue. A chemical analysis with an electron microprobe gave VO₂ 50.40, SO₃ 49.30, total 99.70 wt.%. The empirical formula, calculated on the basis of 5O, is V_0.99S_1.01O₅. The simplified formula is VO(SO₄). Pauflerite is orthorhombic, Pnma, a 7.3890(13), b 6.2740(11), c 7.0788(11) Å, V 328.16(10) ų, Z = 4. The structure has been solved by direct methods and refined to R₁ of 0.034, calculated for the 457 unique observed reflections (|F_o| > 4σ|F_o|). The structure contains one symmetrically independent V⁴⁺ cation in distorted octahedral coordination to the O atoms (one vanadyl V⁴⁺–O bond of 1.607 Å, four bonds of 1.992–1.996 Å, and one bond of 2.267 Å). One symmetrically independent S⁶⁺ cation is tetrahedrally coordinated by four O²⁻ anions with the mean <S⁶⁺–O> bond length of 1.470 Å. The structure of pauflerite consists of a three-dimensional framework of distorted V⁴⁺O₆ octahedra and SO₄ tetrahedra with a titanite-type topology. Pauflerite is a natural analog of β-VO(SO₄). The powder-diffraction pattern was not obtained because of the paucity of natural material. The calculated powder-diffraction pattern is in excellent agreement with that reported for the synthetic analogue (PDF 19–1400). The name chosen honors Peter Paufler, professor at the Technical University of Dresden in recognition of his important contributions to physical and structural crystallography and mineralogy.