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

作者：Demartin Francesco^*; Gramaccioli Carlo Maria; Campostrini Italo

来源：The Canadian Mineralogist, 2010, 48(2): 315-321.

DOI：10.3749/canmin.48.2.315

• adranosite
• new mineral species
• crystal structure
• ammonium sulfates
• Vulcano
• Aeolian Islands
• Italy

The new mineral species adranosite, (NH4)(4)NaAl2(SO4)(4)Cl(OH)(2), was found in a medium- temperature (similar to 250 degrees 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: I4(1)/acd (no. 142) with a 18.118(3), c 11.320(3) angstrom, V 3715.5(13) angstrom(3) and Z = 8. The strongest six reflections in the X-ray powder-diffraction pattern [d(obs) in angstrom(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)(2)O 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)(3.89)K-0.12](Sigma 4.01)Na1.16Al2.09S3.93O15.99 Cl-0.98(OH)(2.03). The end-member formula is (NH4)(4)NaAl2(SO4)(4)Cl(OH)(2). The measured density is 2.15(1) g/cm(3), and D-calc is 2.176 g cm(-3). The mineral is uniaxial (-) with omega = 1.55(1), epsilon = 1.54(1) (lambda = 589 nm). Using single-crystal diffraction data, the structure was refined to a final R = 0.0355 for 596 independent observed reflections [I > 2 sigma(I)]. Adranosite is isostructural with the (NH4)(4)NaFe2(SO4)(4)Cl(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) angstrom] 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) angstrom], 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.

• 出版日期2010-4