DOCSLIB.ORG

RUSSOITE, Nh4clas 2O3(H2O)0.5, a NEW PHYLLOARSENITE MINERAL from SOLFATARA DI POZZUOLI, NAPOLI, ITALY

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
RUSSOITE, Nh4clas 2O3(H2O)0.5, a NEW PHYLLOARSENITE MINERAL from SOLFATARA DI POZZUOLI, NAPOLI, ITALY 3+ RUSSOITE, NH4ClAs 2O3(H2O)0.5, A NEW PHYLLOARSENITE MINERAL FROM SOLFATARA DI POZZUOLI, NAPOLI, ITALY ITALO CAMPOSTRINI, FRANCESCO DEMARTIN, AND MARCO SCAVINI Università degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, I-20133 Milano, Italy. E-mail: [email protected] [Received 8 August 2017; Accepted 23 November 2017; Associate Editor: Charles Geiger] ABSTRACT 3+ The new mineral russoite (IMA 2015-105), NH4ClAs 2O3(H2O)0.5, was found at the Solfatara di Pozzuoli, Pozzuoli, Napoli, Italy, as a fumarolic phase associated with alacranite, dimorphite, realgar, mascagnite, salammoniac and an amorphous arsenic sulfide. It occurs as hexagonal plates up to about 300 μm in diameter and 15 μm thick, in rosette-like intergrowths. On the basis of PXRD measurements and chemical analysis, the mineral was recognized to be identical to the corresponding synthetic phase NH4ClAs2O3(H2O)0.5. Crystals are transparent and colorless, with vitreous lustre and white streak. Tenacity is brittle and fracture is irregular. Cleavage is perfect on {001}. The measured density is 2.89(1) g/cm3, the calculated density is 2.911 g/cm3. The empirical formula, (based on 4.5 anions pfu) is [(NH4)0.94,K0.06]Σ1.00(Cl0.91,Br0.01)Σ0.92As2.02O3(H2O)0.5. Russoite is hexagonal, space group P622, with a = 5.2411(7), c = 12.5948(25) Å, V = 299.62(8) Å3 and Z = 2. The eight strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 12.63(19)(001), 6.32(100)(002), 4.547(75)(100), 4.218(47)(003), 3.094(45)(103), 2.627(46)(110), 2.428(31)(112) and 1.820(28)(115). The structure, was refined to R =0.0518 for 311 reflections with I >2(I) and shows a different location of the ammonium cation and water molecules with respect to that reported for the synthetic analogue. The This is a 'preproof' accepted article for Mineralogical Magazine. This version may be subject to change during the production process. DOI: 10.1180/minmag.2017.081.097. mineral belongs to a small group of phylloarsenite minerals (lucabindiite, torrecillasite, gajardoite). It contains electrically neutral As2O3 layers, topologically identical to those found in lucabindiite and gajardoite between which are ammonium cations and outside of which Cl- anions. Water molecules and additional ammonium cations are located in a layer between two levels of chloride anions. Keywords: russoite; new mineral; arsenite; lucabindiite; torrecillasite; gajardoite. INTRODUCTION The Solfatara di Pozzuoli is one of about 40 volcanoes in the Campi Flegrei area and is located three kilometers from the center of the town of Pozzuoli, Napoli, Italy. Solfatara formed during the third Flegrean eruptive period and dates to about 3700-3900 years ago. Inside the Solfatara some active fumaroles are present, the most important of which is called "Bocca Grande" and has a temperature of about 160 °C. During a research campaign carried out in 2011, a few samples of the new mineral 3+ russoite, NH4ClAs 2O3(H2O)0.5, were collected at the “Bocca Grande” fumarole, where this phase formed as a sublimate product. XRPD measurements and chemical analysis, showed the mineral to be identical to the corresponding synthetic phase NH4ClAs2O3(H2O)0.5 (Edstrand and Blomqvist, 1955). In lack of single crystal suitable for an accurate X-ray structure refinement on the natural product, the XRPD data and the analytical results, perfectly matching those of the synthetic phase, were considered to be sufficient for a positive identification of the new mineral species, which was approved by the IMA Commission on New Minerals, Nomenclature and Classification (IMA. 2015- 105). Its name was chosen to honour Dr. Massimo Russo (b. 1960, –), researcher at Osservatorio Vesuviano, Istituto Nazionale di Geofisica e Vulcanologia, Napoli. His work has been mainly devoted to the mineralogy of Italian volcanoes and he is author of several books and articles on this topic. Holotype material is deposited in the Reference Collection of the DCSSI, Università degli Studi di Milano, catalogue number 2015-01. The recent availability of new material allowed us to obtain more accurate single-crystal intensity data for structure refinement. These data showed a location of the ammonium cation and water molecule 2 different from that proposed by Edstrand and Blomqvist (1955). OCCURRENCE, CHEMICAL DATA AND PHYSICAL PROPERTIES The new mineral russoite was found as a fumarolic phase associated with alacranite, dimorphite, mascagnite, realgar, salammoniac and an amorphous arsenic sulfide. In the same fumarole other interesting and rare minerals are found: adranosite, adranosite-(Fe), efremovite, huizingite-(Al) and godovikovite. Russoite occurs as rosette-like intergrowths or subparallel aggregates formed by hexagonal plates flattened on {001} and bounded by {100} up to about 300 μm in diameter and 15 μm thick, (Figures 1-2). This aggregates sometimes are yellowish due to admixed amorphous arsenic sulfide. Crystals are colorless to white, transparent or translucent, with vitreous lustre and white streak. Tenacity is brittle and fracture is irregular. Cleavage is perfect on {001}. The mineral does not fluoresce in long- or short-wave ultraviolet light. No twinning is apparent. The density, measured by flotation in a diiodomethane/benzene solution is 2.89(1) g/cm3, that calculated using the empirical formula and unit-cell data is 2.911 g/cm3. Due to the minute size of the crystals the Mohs hardness could not be determined. Optically russoite is uniaxial (-) with = 1.810(6) and = 1.650(5) (measured in white light). The calculated mean refractive index using the Gladstone-Dale constants of Mandarino (1976, 1981) is 1.757, which is rated as good. The infrared spectrum of russoite (Figure 3) was recorded in a KBr disk, in the range 4000 – 400 cm-1, using a Jasco FTIR-470 Plus spectrometer. It is consistent with the presence of ammonium [bands at -1 -1 (cm ): 3254, 3; 3145, 22; 1403, 4], water [bands at (cm ): 3454, 3; 3398, 1; 1625, 2] and arsenite (bands at 604 and 670 cm-1) (Farmer, 1974; Busigny et al., 2003). The weak absorption at -1 -1 - about 2400 cm is due to atmospheric CO2, that at 1110 cm might be attributed to minor OH , partially replacing the chloride ion. 3 Quantitative chemical analyses (6) were carried out in EDS mode using a JEOL JSM 5500 LV scanning electron microscope equipped with an IXRF EDS 2000 microprobe (20 kV excitation voltage, 10 pA beam current, 2 μm beam diameter). This analytical method was chosen because crystal intergrowths did not take a good polish and was impossible to prepare a flat polished sample; moreover the crystals are severely damaged by using the WDS technique, even with a low voltage and current and a large diameter of the electron beam. In this case, as reported by Ruste (1979) and Acquafredda and Paglionico (2004), the EDS detector gives more accurate analyses of small volumes of investigated sample also with a probe current lower than 1 nA and this method gives good results also when collecting X-rays emitted from a non perfectly flat surface of the specimen. X-ray intensities were converted to wt% by ZAF quantitative analysis software. The standards employed were: synthetic InAs (As) halite (Cl), synthetic KBr (K, Br). Element concentrations were measured using the K lines for Cl, K, and the L line for As and Br. The mean analytical results are reported in Table 1. No amounts of other elements above 0.1 wt% were detected. Water and ammonium contents were not analyzed because the mineral is intimately mixed with mascagnite and realgar and is not possible to obtain a sufficient amount of pure sample suitable for this kind of analysis. The presence of N was also evident in the EDS spectrum made on selected crystals, however the uncertainties of the measurements were considered too large for a quantitative estimation of this element. Therefore the ammonium and water contents were deduced from the NH4ClAs2O3(H2O)0.5 stoichiometry, taking into account the K content, which partly replaces the ammonium ion (K + NH4 = 1 apfu). The empirical formula (based on 4.5 anions pfu) is: [(NH4)0.94,K0.06]Σ1.00(Cl0.91,Br0.01)Σ0.92As2.02O3(H2O)0.5. The simplified formula is NH4ClAs2O3(H2O)0.5. The X-ray powder-diffraction pattern (Table 2), obtained using a conventional Rigaku DMAX II diffractometer, with graphite monochromatized CuK radiation, is in good agreement with that calculated for the synthetic phase (PDF2 – entry 00-076-1366), whose structure was solved by Edstrand and Blomqvist (1955) on the basis of Weissenberg film measurements. Using the same indexing of the synthetic phase and the program UNITCELL (Holland and Redfern, 1997) the 4 following unit-cell parameters a = 5.259(2), c = 12.590(5) Å, V= 301.55(2) Å3 were refined for russoite. They are in good agreement with those reported for the synthetic phase a = 5.254, c = 12.574 Å. SINGLE-CRYSTAL STRUCTURE DETERMINATION A new sampling, carried out in April 2016, after the approval of russoite as a new mineral by the IMA CNMNC, gave the us opportunity to collect additional specimens with larger aggregates of crystals (up to 0.3 mm), from which fragments apparently suitable for single-crystal structure determination could have been obtained. Indeed, all these fragments are not perfect single crystals, as they are made by several small platelets almost stacked in a parallel way, but slightly misaligned. After many attempts, one fragment was found to be composed by two different individuals only, sufficiently misaligned to allow the collection of a complete set of reflections, suitable for a new structure refinement. The diffracted intensities, corresponding to a complete scan of the reciprocal lattice up to 2= 63.60°, were collected at room temperature using a Bruker Apex II diffractometer equipped with a 2K CCD detector and MoK radiation (λ = 0.71073 Å).
Load more

Recommended publications
  • Download the Scanned
    American Mineralogist, Volume 76, pages299-305, 1991 NEW MINERAL NAMES* JonN L. Javrnon CANMET, 555 Booth Street,Ottawa, Ontario KIA OGl, Canada Eowl,no S. Gnnw Department of Geological Sciences,University of Maine, Orono, Maine 04469, U.S.A. platy either with a rhombic outline, or equant with a L.v.Razin, o.o. AnyuiiteAupb,-A nearly squareoutline. The mineral forms complex inter- ,,u".lJ,lt,liD possibly new intermetallic of gold and lead. Mineral . Zhumal, growths of three types with native lead, resulting I l(4), 88-96 (in Russian). from breakdown of solid solutions. In the intergrowths, anyuiite typically forms platy aggregatesranging from 1- Electron-microprobe analysesof the mineral and of an 50 pm acrossand 100-900 pm long, and prismatic crys- gave antimony-bearing variety Au 32.6, 34.3, 36.7, Ag tals 50 x 100 pm. Associatedminerals include ilmenite, 0.35,not detected,Pb 64.8, 59.0,52.9,Sb 0.3, 5.8, 10.2, titanian magnetite,chrome spinel, hematite, pyrite, chal- sum 98.05, 99.1, 99.8 wto/0,corresponding to (Au,or,- copyrite, and apatite. Sourcesof the mineral are small A& orr)",or, (Pb, n*rSbo o,r)", ooo, Au, oon(Pb, ,,rSbo ,rr)", ooo, Hercynian ultrabasic-gabbroid massivesderived from a and Au, r0r(Pbr s07sb0onr)", *0. Fragmentsare opaque, sil- platinum-bearing dunite-harzburgite magmatic forma- gray, very luster metallic. Oxidizes after 1.5-2 days, be- tion in the Anyui eugeosynclineof the Koryak-Kam- gray (sil- coming dull lead-gray. In reflected light, light chatka fold province. The mineral is named for the lo- very) with a faint creamy tint, fairly highly reflecting; cality (Bolshoi Anyui River basin).
    [Show full text]
  • Ammoniomagnesiovoltaite, a New Voltaite-Related Mineral Species from Pécs-Vasas, Hungary
    65 The Canadian Mineralogist Vol. 50, pp. 65-72 (2012) DOI : 10.3749/canmin.50.1.65 AMMONIOMAGNESIOVOLTAITE, A NEW VOLTAITE-RELATED MINERAL SPECIES FROM PÉCS-VASAS, HUNGARY SÁNDOR SZAKÁLL§ Department of Mineralogy and Petrology, University of Miskolc, H-3515 Miskolc, Egyetemváros, Hungary ISTVÁN SAJÓ Institute of Materials and Environmental Chemistry, Research Center for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary BÉLA FEHÉR Department of Mineralogy, Herman Ottó Museum, Kossuth u. 13, H-3525 Miskolc, Hungary SIMONA BIGI Department of Earth Sciences, University of Modena and Reggio Emilia, Via Santa Eufemia 19, I-41100 Modena, Italy ABSTRACT Ammoniomagnesiovoltaite (IMA no. 2009-040) was found on a burning coal dump in an abandoned open coal pit at Pécs-Vasas, Mecsek Mountains, South Hungary. It is closely associated with tschermigite, sabieite, kieserite, pickeringite, and hexahydrite, but other ammonium minerals (salammoniac, mascagnite, clairite, boussingaultite, efremovite, koktaite, mohrite, ammoniojarosite, godovikovite, letovicite) as well as native sulfur, millosevichite, alunogen, metavoltine, voltaite, gypsum, anhydrite, halotrichite, butlerite, jarosite, and copiapite also occur in the surrounding area. Ammoniomagnesiovoltaite was formed by the interaction of organic matter with oxidizing iron sulfides (pyrite and marcasite). It forms crusts consisting of cubo-octahedral and octahedral crystals up to 0.05 mm in size. The mineral is translucent and pale yellow to yellowish brown in color, with white streak and vitreous luster. Its Mohs hardness is about 2-3 and the measured density is 2.55(1) g/cm3. Cleavage was not observed; fracture is uneven. Optically it is isotropic with n = 1.60(1).
    [Show full text]
  • Crystal Chemistry and High-Temperature Behaviour of Ammonium Phases Nh4mgcl3·6H2O and 3+ (NH4)2Fe Cl5·H2O from the Burned Dumps of the Chelyabinsk Coal Basin
    minerals Article Crystal Chemistry and High-Temperature Behaviour of Ammonium Phases NH4MgCl3·6H2O and 3+ (NH4)2Fe Cl5·H2O from the Burned Dumps of the Chelyabinsk Coal Basin Andrey A. Zolotarev Jr. 1,*, Elena S. Zhitova 1,2 , Maria G. Krzhizhanovskaya 1, Mikhail A. Rassomakhin 3, Vladimir V. Shilovskikh 4 and Sergey V. Krivovichev 1,5 1 Department of Crystallography, Institute of Earth Sciences, St. Petersburg State University, University Emb. 7/9, 199034 Saint-Petersburg, Russia 2 Institute of Volcanology and Seismology FEB RAS, Piip Blvd 9, 683006 Petropavlovsk-Kamchatsky, Russia 3 South Urals Federal Research Center of Mineralogy and Geoecology of UB RAS, 456317 Miass, Russia 4 Geomodel Research Centre, St. Petersburg State University, University Emb. 7/9, 199034 Saint-Petersburg, Russia 5 Federal Research Center, Kola Science Center, RAS, Fersmana Str. 14, 184209 Apatity, Russia * Correspondence: [email protected] or [email protected]; Tel.: +7-812-350-66-88 Received: 30 July 2019; Accepted: 12 August 2019; Published: 14 August 2019 Abstract: The technogenic mineral phases NH MgCl 6H O and (NH ) Fe3+Cl H O from the burned 4 3· 2 4 2 5· 2 dumps of the Chelyabinsk coal basin have been investigated by single-crystal X-ray diffraction, scanning electron microscopy and high-temperature powder X-ray diffraction. The NH MgCl 6H O 4 3· 2 phase is monoclinic, space group C2/c, unit cell parameters a = 9.3091(9), b = 9.5353(7), c = 13.2941(12) Å, β = 90.089(8) and V = 1180.05(18) Å3. The crystal structure of NH MgCl 6H O was refined to ◦ 4 3· 2 R = 0.078 (wR = 0.185) on the basis of 1678 unique reflections.
    [Show full text]
  • A Minerals File:///F:/ABRIANTO/METALURGI%20EKSTRAKTIF/Metalurgi%2
    A Minerals file:///F:/ABRIANTO/METALURGI%20EKSTRAKTIF/Metalurgi%2... [ Up ] [ A Minerals ] [ B Minerals ] [ C Minerals ] [ D Minerals ] [ E Minerals ] [ F Minerals ] [ G Minerals ] [ H Minerals ] [ I Minerals ] [ J Minerals ] [ K Minerals ] [ L Minerals ] [ M Minerals ] [ N Minerals ] [ O Minerals ] [ P Minerals ] [ Q Minerals ] [ R Minerals ] [ S Minerals ] [ T Minerals ] [ U Minerals ] [ V Minerals ] [ W Minerals ] [ X Minerals ] [ Y Minerals ] [ Z Minerals ] A Index of Mineral Species [What's New][Mineral Galleries][Sale Items][About Us][Contacts] At AA Mineral Specimens, we source quality Mineral Specimens, Fossils, Gemstones, Decorative Stones, Lapidary Material and Specimen Sets world-wide This alphabetical listing of A minerals include synonyms of accepted mineral names, pronunciation of that name, name origins, and locality information. Visit our expanded selection of mineral pictures. LEGEND Minerals identified with this icon have a sound file, courtesy of The Photo-Atlas of Minerals, which gives the pronunciation of the mineral name. Minerals identified with this icon have an image or picture in the database which may be viewed. Minerals identified with this icon have a Java crystal form, created with the program JCrystal, which can be manipulated and rotated. This icon links the mineral to the locality-rich information contained in Mindat.org. Minerals identified with this icon are radioactive. - Detectable with very sensitive instruments, - very mild, - weak, - strong, - very strong, - dangerous. * Mineral Name is Not IMA Approved. ! New Dana Classification Number Has Been Changed or Added. ? IMA Discredited Mineral Species Name. Ab0 * (see Anorthite ) Ab100 * (see Albite ) Ab20 * (see Bytownite ) Ab40 * (see Labradorite ) Ab60 * (see Andesine ) Ab80 * (see Oligoclase ) Abelsonite Ni++C31H32N4 NAME ORIGIN: Named after Philip H.
    [Show full text]
  • New Mineral Names*,†
    American Mineralogist, Volume 99, pages 2150–2158, 2014 New Mineral Names*,† FERNANDO CÁMARA1, G. DIEGO GATTA2, YULIA UVAROVA3, OLIVIER C. GAGNE4 AND DMITRIY I. BELAKOVSKIY5 1Dipartimento di Scienze della Terra, Universitá di degli Studi di Torino, Via Valperga Caluso, 35-10125 Torino, Italy 2Dipartimento Scienze della Terra, Universitá degli Studi di Milano, Via Botticelli, 23-20133 Milano, Italy 3CSIRO Earth Science and Resource Engineering, MDU Flagship, ARRC, 26 Dick Perry Avenue, Kensington, Western Australia 6151, Australia 4Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, R3T 3R1, Canada 5Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18 korp. 2, Moscow 119071, Russia IN THIS ISSUE This New Mineral Names has entries for 14 new minerals, including ammoniomagnesiovoltaite, arangasite, atelisite-(Y), boscardinite, carlgieseckeite-(Nd), cupromolybdite, hezuolinite, jacutingaite, laptevite-(Ce), lavoisierite, paseroite, postite, tarbagataite, and zavalíaite. AMMONIOMAGNESIOVOLTAITE* (6.87–7.27), K2O 0.05 (0.05–0.06), (NH4)2O (by spectrophotom- S. Szakáll, I. Sajó, B. Fehér, and S. Bigi (2012) Ammoniomag- etry) 3.11, and H2O (calc) 17.72, total 98.17 wt%. Weight percent 2+ 3+ 2+ 2+ nesiovoltaite, a new voltaite-related mineral species from for Fe and Fe are determined assuming (Mg + Fe + Mn )/ 3+ Pécs-Vasas, Hungary. Canadian Mineralogist, 50(1), 65–72. (Fe + Al) = 5/4, and by stoichiometry for H2O. This leads to 2+ the empirical formula [(NH4)2.18K0.02]Σ2.20 (Mg3.19Fe1.51Mn0.30)Σ5.00 3+ Ammoniomagnesiovoltaite (IMA-2009-040), ideally (Fe2.81Al1.19)Σ4.00S10.87O44.70∙18H2O on the basis of (Mg + Mn + Fe + 3+ Al) = 9 apfu.
    [Show full text]