• journal_title：The Canadian Mineralogist
• Contributor：Francesco Demartin ; Carlo Maria Gramaccioli ; Italo Campostrini
• Publisher：Mineralogical Association of Canada
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.3749/canmin.48.2.315
• journal_abbrev：Can Mineral
• issn：0008-4476
• volume：48
• issue：2
• firstpage：315
• section：Articles

The new mineral species adranosite, (NH₄)₄NaAl₂(SO₄)₄Cl(OH)₂, was found in a medium-temperature (~250°C) active fumarole at La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy. The mineral occurs on a pyroclastic breccia as colorless to white sprays of prismatic crystals up to 0.3 mm in length, in association with aiolosite, alunite, anhydrite, bismuthinite, sassolite, demicheleite-(Br), demicheleite-(Cl), panichiite and IMA 2009–049. The mineral is tetragonal, space group: I4₁/acd (no. 142) with a 18.118(3), c 11.320(3) Å, V 3715.5(13) ų and Z = 8. The strongest six reflections in the X-ray powder-diffraction pattern [d_obs in Å(I)(hkl)] are: 2.980(100)(152), 2.265(87)(080), 4.530(86)(040), 6.398(80)(220), 3.020(65)(060) and 3.202(47)(440). The average result of chemical analyses (wt.%) is: Na₂O 5.88, Al₂O₃ 17.40, K₂O 0.90, (NH₄)₂O 16.52, SO₃ 51.31, Cl 5.68, H₂O 2.99, –O=Cl −1.28, for a total of 99.40. The empirical formula (based on 19 anions) is: [(NH₄)_3.89K_0.12]_∑4.01Na_1.16Al_2.09S_3.93O_15.99 Cl_0.98(OH)_2.03. The end-member formula is (NH₄)₄NaAl₂(SO₄)₄Cl(OH)₂. The measured density is 2.15(1) g/cm³, and D_calc is 2.176 g cm⁻³. The mineral is uniaxial (−) with ω = 1.55(1), ε = 1.54(1) (λ = 589 nm). Using single-crystal diffraction data, the structure was refined to a final R = 0.0355 for 596 independent observed reflections [I > 2σ(I)]. Adranosite is isostructural with the (NH₄)₄NaFe₂(SO₄)₄Cl(OH)₂ phase found in a burning coal dump. Building blocks of the structure are AlO₆ octahedra [Al–O in the range 1.862(1)–1.923(1) Å] and SO₄ tetrahedra, which are linked together to form spiraling chains parallel to [001]. There are also NaO₄Cl₂ square tetragonal bipyramids [Na–O 2.360(1), Na–Cl 2.830(1) Å], linked together by sharing the Cl atoms at the corners. The ammonium ions occupy the voids in the resulting framework and interact with the neighboring atoms via hydrogen bonds.