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) Å3 and Z = 8. The strongest six reflections in the X-ray powder-diffraction pattern [dobs 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)3.89K0.12]S4.01Na1.16Al2.09S3.93O15.99 Cl0.98(OH)2.03. The end-member formula is (NH4)4NaAl2(SO4)4Cl(OH)2. The measured density is 2.15(1) g/cm3, and Dcalc is 2.176 g cm–3. The mineral is uniaxial (–) with v = 1.55(1),  = 1.54(1) (l = 589 nm). Using single-crystal diffraction data, the structure was refined to a final R = 0.0355 for 596 independent observed reflections [I > 2s(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.

ADRANOSITE, (NH4)4NaAl2(SO4)4Cl(OH)2, A NEW AMMONIUM SULFATE CHLORIDE FROM LA FOSSA CRATER, VULCANO, AEOLIAN ISLANDS, ITALY / F. Demartin, C.M. Gramaccioli, I. Campostrini. - In: CANADIAN MINERALOGIST. - ISSN 0008-4476. - 48:2(2010), pp. 315-321.

ADRANOSITE, (NH4)4NaAl2(SO4)4Cl(OH)2, A NEW AMMONIUM SULFATE CHLORIDE FROM LA FOSSA CRATER, VULCANO, AEOLIAN ISLANDS, ITALY

F. Demartin;C.M. Gramaccioli;I. Campostrini
2010

Abstract

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) Å3 and Z = 8. The strongest six reflections in the X-ray powder-diffraction pattern [dobs 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)3.89K0.12]S4.01Na1.16Al2.09S3.93O15.99 Cl0.98(OH)2.03. The end-member formula is (NH4)4NaAl2(SO4)4Cl(OH)2. The measured density is 2.15(1) g/cm3, and Dcalc is 2.176 g cm–3. The mineral is uniaxial (–) with v = 1.55(1),  = 1.54(1) (l = 589 nm). Using single-crystal diffraction data, the structure was refined to a final R = 0.0355 for 596 independent observed reflections [I > 2s(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.
Adranosite; Aeolian islands; Ammonium sulfates; Crystal structure; Italy; New mineral species; Vulcano
Settore CHIM/03 - Chimica Generale e Inorganica
Settore GEO/06 - Mineralogia
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/162266
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