DOCSLIB.ORG

An SEM, EDS and Vibrational Spectroscopic Study of the Silicate Mineral

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An SEM, EDS and Vibrational Spectroscopic Study of the Silicate Mineral Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 216–220 Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa An SEM, EDS and vibrational spectroscopic study of the silicate mineral meliphanite (Ca,Na)2Be[(Si,Al)2O6(F,OH)] ⇑ Ray L. Frost a, , Andrés López a, Frederick L. Theiss a, Antônio Wilson Romano b, Ricardo Scholz b a School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia b Geology Department, School of Mines, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG 35400-00, Brazil highlights graphical abstract Meliphanite (Ca,Na)2Be[(Si,Al)2O6(F,OH)] is a crystalline sodium calcium beryllium silicate. The mineral was characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX). EDX analysis shows high concentrations of Si and Ca and low amounts of Na, Al and F. Raman spectroscopy identifies bands in the OH stretching region. article info abstract Article history: The mineral meliphanite (Ca,Na)2Be[(Si,Al)2O6(F,OH)] is a crystalline sodium calcium beryllium silicate Received 8 July 2014 which has the potential to be used as piezoelectric material and for other ferroelectric applications. Received in revised form 24 August 2014 The mineral has been characterized by a combination of scanning electron microscopy (SEM) with energy Accepted 11 September 2014 dispersive spectroscopy (EDS) and vibrational spectroscopy. EDS analysis shows a material with high Available online 2 October 2014 concentrations of Si and Ca and low amounts of Na, Al and F. Beryllium was not detected. Raman bands at 1016 and 1050 cmÀ1 are assigned to the SiO and AlOH stretching vibrations of three dimensional silox- Keywords: ane units. The infrared spectrum of meliphanite is very broad in comparison with the Raman spectrum. Meliphanite Raman bands at 472 and 510 cmÀ1 are assigned to OSiO bending modes. Raman spectroscopy identifies Melitite Leucophanite bands in the OH stretching region. Raman spectroscopy with complimentary infrared spectroscopy Raman spectroscopy enables the characterization of the silicate mineral meliphanite. Infrared spectroscopy Ó 2014 Elsevier B.V. All rights reserved. Introduction may be observed among samples of meliphanite from orange to black. The mineral is known from several places worldwide [2–4] The mineral meliphanite has the formula (Ca,Na)2Be[(Si,Al)2- and is often collected as a semi-precious jewel (please see http:// O6(F,OH)] [1]. The mineral was discovered in 1852 and is named www.gemsociety.org/article/meliphanite-jewelry-and-gemstone- after the Greek word for honey because of the honey like colour information/). It should be noted that there are a range of formulae of the mineral. Please see the picture of the meliphanite mineral which are given for meliphanite including [(Ca,Na)2Be(Si,Al)2 used in the graphical abstract. Considerable variation in colour (O,OH,F)7], Ca(Na, Ca)BeSi206F, (Ca,Na)2Be[(Si,Al)2O6(F,OH)] and Ca4(Na,Ca)4Be4AlSi7O24(F,O)4 [5]. It is apparent that the exact for- mula of the mineral remains to be precisely determined and of ⇑ Corresponding author. Tel.: +61 7 3138 2407; fax: +61 7 3138 1804. course, it may vary according to the sample origin. It is apparent E-mail address: [email protected] (R.L. Frost). http://dx.doi.org/10.1016/j.saa.2014.09.018 1386-1425/Ó 2014 Elsevier B.V. All rights reserved. R.L. Frost et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 136 (2015) 216–220 217 that some of the physical properties of the mineral meliphanite Scanning electron microscopy (SEM) remain to be measured. The mineral is tetragonal with space group I4 bar and Z =8[1]. Experiments and analyses involving electron microscopy were The cell dimensions are a = 10.5257(3) Å, c = 9.8868(4) Å, performed in the Center of Microscopy of the Universidade Federal V = 1095.37(8) Å3. The crystal structure was solved by comparison de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil (http:// with the silicate mineral melitite [1]. The crystal structure consists www.microscopia.ufmg.br). of infinite sheets of SiO4 and BeO4 tetrahedra between which Ca or Meliphanite crystals were coated with a 5 nm layer of evapo- (Ca, Na) are sandwiched. The coordination polyhedra of these cat- rated carbon. Secondary Electron and Backscattering Electron ions are distorted trigonal prisms. Grice and Hawthorne [5] refined images were obtained using a JEOL JSM-6360LV equipment. Qual- the structure of meliphanite and state that the anomalous biaxial itative and semi-quantitative chemical analyses in the EDS mode character of tetragonal meliphanite is likely due to stress within were performed with a ThermoNORAN spectrometer model Quest the crystal structure as a result of twinning. The presence of alu- and was applied to support the mineral characterization. The same minium in the tetrahedra layers enables the distinction between sample was used for SEM with EDS and vibrational spectroscopy. meliphanite and leucophanite, Ca4Na4Be4Si8O24F4 [6]. These two minerals are noted for their fluorescent properties [7] (see http:// Raman microprobe spectroscopy www.csiro.au/luminescence/Default.aspx). Gugiaite Ca2BeSi2O7 is a melitite mineral and is named for the Chinese village of Gugia Crystals of meliphanite were placed on a polished metal surface where it was first discovered [8]. It occurs mostly in skarns with on the stage of an Olympus BHSM microscope, which is equipped melanite adjacent to an alkali syenite. Shortly after the discovery with 10 ,20 , and 50 objectives. The microscope is part of a of gugiaite, it was noted that a new name was unnecessary as it    Renishaw 1000 Raman microscope system, which also includes a could have been considered an end member of meliphanite differ- monochromator, a filter system and a CCD detector (1024 pixels). ing mainly in containing much less Na and F. Recent data have con- The Raman spectra were excited by a Spectra-Physics model 127 firmed that gugiaite does differ from meliphanite optically and He–Ne laser producing highly polarized light at 633 nm and col- structurally [5]. Gugiaite is a melilite and is distinctly different lected at a nominal resolution of 2 cmÀ1 and a precision of ±1 cmÀ1 from other beryllium minerals such as meliphanite and leucopha- in the range between 200 and 4000 cmÀ1. Repeated acquisitions on nite [5]. These beryllium bearing minerals are strongly the crystals using the highest magnification (50 ) were accumu- piezoelectric.  lated to improve the signal to noise ratio of the spectra. Raman No Raman spectroscopic studies of meliphanite and related Spectra were calibrated using the 520.5 cmÀ1 line of a silicon minerals have been forthcoming [9]. Some infrared studies of wafer. The Raman spectrum of at least 10 crystals was collected selected calcium silicates have been undertaken [10,11]. Few stud- to ensure the consistency of the spectra. An image of the melipha- ies have been made on beryllium containing silicates. Studies of nite crystals measured is shown in the graphical abstract. Clearly hydrogen bonding in silicates relates the position of the hydroxyl the crystals of meliphanite are readily observed, making the vibra- stretching vibration to the hydrogen bond distances [12]. Some tional spectroscopic measurements readily obtainable. discussion in the literature relates to the presence of OH groups in the structure of meliphanite [5]. Some Raman spectra of calcium silicates have been collected and a number of the spectra were Infrared spectroscopy shown to be dependent upon the number of condensed silica tet- rahedra [13]. Such detailed assignment of infrared and Raman Infrared spectra were obtained using a Nicolet Nexus 870 FTIR bands for a wide range of silicate structures was made by Dowty spectrometer with a smart endurance single bounce diamond [14–17]. The thermal decomposition of calcium silicates has also ATR cell. Spectra over the 4000–525 cmÀ1 range were obtained been measured [18–20]. by the co-addition of 128 scans with a resolution of 4 cmÀ1 and a There is an apparent lack of information on the vibrational spec- mirror velocity of 0.6329 cm/s. Spectra were co-added to improve tra of meliphanite. The reason for such a lack of information is not the signal to noise ratio. known; yet the mineral contains siloxane units. Such units lend Spectral manipulation such as baseline correction/adjustment themselves to vibrational spectroscopy. Raman spectroscopy has and smoothing were performed using the Spectracalc software proven most useful for the study of mineral structure [21–24]. package GRAMS (Galactic Industries Corporation, NH, USA). Band The objective of this research is to report the Raman and infrared component analysis was undertaken using the Jandel ‘Peakfit’ soft- spectra of meliphanite and to relate the spectra to the mineral ware package that enabled the type of fitting function to be structure. selected and allows specific parameters to be fixed or varied accordingly. Band fitting was done using a Lorentzian–Gaussian cross-product function with the minimum number of component Experimental bands used for the fitting process. The Gaussian–Lorentzian ratio was maintained at values greater than 0.7 and fitting was under- Samples description and preparation taken until reproducible results were obtained with squared corre- lations of r2 greater than 0.995. The meliphanite sample studied in this work forms part of the collection of the Geology Department of the Federal University of Ouro Preto, Minas Gerais, Brazil, with sample code SAC-144. The Results and discussion mineral originated from from Østskogen larvikittbrudd, Tvedalen (Tveidalen), Larvik kommune, Vestfold fylke, Norway. A detailed Chemical characterization study of the locality was published [25].
Load more

Recommended publications
  • Stitial Oxide Ions Synthesized by Direct Crystallization
    La2Ga3O7.5: a metastable ternary melilite with a super-excess of inter- stitial oxide ions synthesized by direct crystallization of the melt Jintai Fan, Vincent Sarou-Kanian, Xiaoyan Yang, Maria Diaz-Lopez, Franck Fayon, Xiaojun Kuang, Michael Pitcher, Mathieu Allix To cite this version: Jintai Fan, Vincent Sarou-Kanian, Xiaoyan Yang, Maria Diaz-Lopez, Franck Fayon, et al.. La2Ga3O7.5: a metastable ternary melilite with a super-excess of inter- stitial oxide ions synthe- sized by direct crystallization of the melt. Chemistry of Materials, American Chemical Society, 2020, 32 (20), pp.9016-9025. 10.1021/acs.chemmater.0c03441. hal-02959774 HAL Id: hal-02959774 https://hal.archives-ouvertes.fr/hal-02959774 Submitted on 7 Oct 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. La2Ga3O7.5: a metastable ternary melilite with a super-excess of inter- stitial oxide ions synthesized by direct crystallization of the melt Jintai Fan,1,2 Vincent Sarou-Kanian,1 Xiaoyan Yang,3 Maria Diaz-Lopez,4,5 Franck Fayon,1 Xiaojun Kuang,3,6 Michael J. Pitcher1* and Mathieu Allix1* 1 CNRS, CEMHTI UPR3079, 45071 Orléans, France 2 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai, 201800, P.
    [Show full text]
  • Optical Properties of Common Rock-Forming Minerals
    AppendixA __________ Optical Properties of Common Rock-Forming Minerals 325 Optical Properties of Common Rock-Forming Minerals J. B. Lyons, S. A. Morse, and R. E. Stoiber Distinguishing Characteristics Chemical XI. System and Indices Birefringence "Characteristically parallel, but Mineral Composition Best Cleavage Sign,2V and Relief and Color see Fig. 13-3. A. High Positive Relief Zircon ZrSiO. Tet. (+) 111=1.940 High biref. Small euhedral grains show (.055) parallel" extinction; may cause pleochroic haloes if enclosed in other minerals Sphene CaTiSiOs Mon. (110) (+) 30-50 13=1.895 High biref. Wedge-shaped grains; may (Titanite) to 1.935 (0.108-.135) show (110) cleavage or (100) Often or (221) parting; ZI\c=51 0; brownish in very high relief; r>v extreme. color CtJI\) 0) Gamet AsB2(SiO.la where Iso. High Grandite often Very pale pink commonest A = R2+ and B = RS + 1.7-1.9 weakly color; inclusions common. birefracting. Indices vary widely with composition. Crystals often euhedraL Uvarovite green, very rare. Staurolite H2FeAI.Si2O'2 Orth. (010) (+) 2V = 87 13=1.750 Low biref. Pleochroic colorless to golden (approximately) (.012) yellow; one good cleavage; twins cruciform or oblique; metamorphic. Olivine Series Mg2SiO. Orth. (+) 2V=85 13=1.651 High biref. Colorless (Fo) to yellow or pale to to (.035) brown (Fa); high relief. Fe2SiO. Orth. (-) 2V=47 13=1.865 High biref. Shagreen (mottled) surface; (.051) often cracked and altered to %II - serpentine. Poor (010) and (100) cleavages. Extinction par- ~ ~ alleL" l~4~ Tourmaline Na(Mg,Fe,Mn,Li,Alk Hex. (-) 111=1.636 Mod. biref.
    [Show full text]
  • THE MELILITE (Gh50) SKARNS of ORAVIT¸A, BANAT, ROMANIA: TRANSITION to GEHLENITE (Gh85) and to VESUVIANITE
    1255 The Canadian Mineralogist Vol. 41, pp. 1255-1270 (2003) THE MELILITE (Gh50) SKARNS OF ORAVIT¸A, BANAT, ROMANIA: TRANSITION TO GEHLENITE (Gh85) AND TO VESUVIANITE ILDIKO KATONA Laboratoire de Pétrologie, Modélisation des Matériaux et Processus, Université Pierre et Marie Curie, 4, Place Jussieu, F-75252 Paris, Cedex 05, France MARIE-LOLA PASCAL§ CNRS–ISTO (Institut des Sciences de la Terre d’Orléans), 1A, rue de la Férollerie, F-45071 Orléans, Cedex 02, France MICHEL FONTEILLES Laboratoire de Pétrologie, Modélisation des Matériaux et Processus, Université Pierre et Marie Curie, 4, Place Jussieu, F-75252 Paris, Cedex 05, France JEAN VERKAEREN Unité de Géologie, Université Catholique de Louvain-la-Neuve, Bâtiment Mercator, 3, Place Louis Pasteur, Louvain-la-Neuve, Belgium ABSTRACT Almost monomineralic Mg-rich gehlenite (~Gh50Ak46Na-mel4) skarns occur in a very restricted area along the contact of a diorite intrusion at Oravit¸a, Banat, in Romania, elsewhere characterized by more typical vesuvianite–garnet skarns. In the vein- like body of apparently unaltered gehlenite, the textural relations of the associated minerals (interstitial granditic garnet and, locally, monticellite, rare cases of exsolution of magnetite in the core zone of melilite grains) suggest that the original composi- tion of the gehlenite may have been different, richer in Si, Mg, Fe (and perhaps Na), in accordance with the fact that skarns are the only terrestrial type of occurrence of gehlenite-dominant melilite. The same minerals, monticellite and a granditic garnet, appear in the retrograde evolution of the Mg-rich gehlenite toward compositions richer in Al, the successive stages of which are clearly displayed, along with the final transformation to vesuvianite.
    [Show full text]
  • The Crystal Structure of Synthetic Soda Melilite, Canaaisi207 1. Introduction
    Zeitschrift fUr Kristallographie, Bd. 131, S. 314--321 (1970) The crystal structure of synthetic soda melilite, CaNaAISi207 By S. JOHN LOUISNATHAN Department of the Geophysical Sciences, The University of Chicago, Chicago (Received 25 August 1969) Auszug Die Kristallstruktur von synthetischem N atriummelilith wurde aus Dif- fraktometerdaten bis R = 5,10/0 verfeinert. Die Verbindung hat die gleiche Struktur wie die iibrigen, natiirlich vorkommenden Melilithe. Die Aluminium- und Siliciumatome sind in der Struktur geordnet, die Calcium- und Natrium- atome statistisch verteilt. Abstract The crystal structure of synthetic soda melilite was refined to R = 5.10/0 from three-dimensional diffractometer data. Soda melilite is isostructural with the other naturally-occuring melilites. Aluminum and Si atoms are ordered in the structure while Ca and N a atoms are disordered. 1. Introduction The literature on the melilite group of minerals with a discussion of the various proposed end-members was reviewed by CHRISTIE (1961 a and b; 1962). After prolonged discussion it is now generally accepted that CaNaAlSi207, called soda melilite, can be established as an end member, partly represented in some natural melilites. YODER (1964) showed that pure soda melilite is stable only at pressures in excess of 4 kbar. Its optical properties were determined by SCHAIRER, YODER and TILLEY (1965). The crystal-structure determination of soda melilite was under- taken as a part of a systematic structural study of the melilite group. The general composition of a melilite can be written as (Ca,Na)2 (Mg,Al)(Al,Si)207. Order-disorder of Mg,Al and Si among the tetra- hedral sites and diadochy of Ca, N a etc.
    [Show full text]
  • Iron Making in Argyll
    HISTORIC ARGYLL 2009 Iron smelting in Argyll, and the chemistry of the process by Julian Overnell, Kilmore. The history of local iron making, particularly the history of the Bonawe Furnace, is well described in the Historic Scotland publication of Tabraham (2008), and references therein. However, the chemistry of the processes used is not well described, and I hope to redress this here. The iron age started near the beginning of the first millennium BC, and by the end of the first millennium BC sufficient iron was being produced to equip thousands of troops in the Roman army with swords, spears, shovels etc. By then, local iron making was widely distributed around the globe; both local wood for making charcoal, and (in contrast to bronze making) local sources of ore were widely available. The most widely distributed ore was “bog iron ore”. This ore was, and still is, being produced in the following way: Vegetation in stagnant water starts to rot and soon uses up all the available oxygen, and so produces a water at the bottom with no oxygen (anaerobic) which also contains dissolved organic compounds. This solution is capable of slowly leaching iron from the soils beneath to produce a weak solution of dissolved iron (iron in the reduced, ferrous form). Under favourable conditions this solution percolates down until it meets some oxygen (or oxygenated water) at which point the iron precipitates (as the oxidized ferric form). This is bog iron ore and comprises a somewhat ill-defined brown compound called limonite (FeOOH.nH2O), often still associated with particles of sand etc.
    [Show full text]
  • The Minerals of Tasmania
    THE MINERALS OF TASMANIA. By W. F. Petterd, CM Z.S. To the geologist, the fascinating science of mineralogy must always be of the utmost importance, as it defines with remarkable exactitude the chemical constituents and com- binations of rock masses, and, thus interpreting their optical and physical characters assumed, it plays an important part part in the elucidation of the mysteries of the earth's crust. Moreover, in addition, the minerals of a country are invari- ably intimately associated with its industrial progress, in addition to being an important factor in its igneous and metamorphic geology. In this dual aspect this State affords a most prolific field, perhaps unequalled in the Common- wealth, for serious consideration. In this short article, I propose to review the subject of the mineralogy of this Island in an extremely concise manner, the object being, chiefly, to afford the members of the Australasian Association for the Advancement of Science a cursory glimpse into Nature's hidden objects of wealth, beauty, and scientific interest. It will be readily understood that the restricted space at the disposal of the writer effectually prevents full justice being done to an absorbing subject, which is of almost universal interest, viewed from the one or the other aspect. The economic result of practical mining operations, as carried on in this State, has been of a most satisfactory character, and has, without doubt, added greatly to the national wealth ; but, for detailed information under this head, reference must be made to the voluminous statistical information, and the general progress, and other reports, issued by the Mines Department of the local Government.
    [Show full text]
  • Sequence of Mineral Formation, Spinel-Perovskite-Spinel-Melilite, Does Not Agree with the Equilibrium Condensation Model (4)
    MICRO-1JII-Y OF CALCIUM-ALUMINUM43GH INCLUSIONS FROM AL;LENDE. Ian D. Hutcheon, University of Chicago, Chicago, IL 60637. Figh resolution scanning electron microscope (SEM) observations of separated phases from Ca-Al-rieh coarse-mined inclusions from Allende have revealed a fascinating wealth of micmn-&ze nrirreml gra2ns whose strmctures are not onkv eye-catching but uniquely infomtive as well. Such varied mineralogies as 0.4 pm perovskite hex+agons on spinel or 1 um spinel pyramids on hibonite as well as 0.1pm Fe grains inside vesicles in melilite and Ni-Fe particles in spinel raise questions concerning the fomtion of coarse- grained inclusions which existing models cannot answer. The texture of micron-size crystals and their pin-to-grain contacts generally argue for condensation, while the mineralogy of neighboring phases is often more con- asistent with liquid crystallization. We have examined five coarse-pained Allende.inclusions, using crystals hand-picked from the same mineral separates.used in oxygen isotope (1)and trace element (2) studies. Minerals were identified with.a solid state x-ray analyzer. The most striking feature we have observed is the ubiquitiaus presence of small perovskite crystals ranging in size from < 0.1 pm to 10 urn, epitaxially . grown on the exterior surfaces of euhedral spinel grains. Perovskite is most abundant in A1 1-16, a Type A inclusion (3) in which spinel is originally poikilitically enclosed by melilite. Numerous spinels survive the mineral separation wikh their original surfaces intact and it is these pristine external surfaces which are invariably covered by epitaxial pervoskite crystals.
    [Show full text]
  • Minerals Found in Michigan Listed by County
    Michigan Minerals Listed by Mineral Name Based on MI DEQ GSD Bulletin 6 “Mineralogy of Michigan” Actinolite, Dickinson, Gogebic, Gratiot, and Anthonyite, Houghton County Marquette counties Anthophyllite, Dickinson, and Marquette counties Aegirinaugite, Marquette County Antigorite, Dickinson, and Marquette counties Aegirine, Marquette County Apatite, Baraga, Dickinson, Houghton, Iron, Albite, Dickinson, Gratiot, Houghton, Keweenaw, Kalkaska, Keweenaw, Marquette, and Monroe and Marquette counties counties Algodonite, Baraga, Houghton, Keweenaw, and Aphrosiderite, Gogebic, Iron, and Marquette Ontonagon counties counties Allanite, Gogebic, Iron, and Marquette counties Apophyllite, Houghton, and Keweenaw counties Almandite, Dickinson, Keweenaw, and Marquette Aragonite, Gogebic, Iron, Jackson, Marquette, and counties Monroe counties Alunite, Iron County Arsenopyrite, Marquette, and Menominee counties Analcite, Houghton, Keweenaw, and Ontonagon counties Atacamite, Houghton, Keweenaw, and Ontonagon counties Anatase, Gratiot, Houghton, Keweenaw, Marquette, and Ontonagon counties Augite, Dickinson, Genesee, Gratiot, Houghton, Iron, Keweenaw, Marquette, and Ontonagon counties Andalusite, Iron, and Marquette counties Awarurite, Marquette County Andesine, Keweenaw County Axinite, Gogebic, and Marquette counties Andradite, Dickinson County Azurite, Dickinson, Keweenaw, Marquette, and Anglesite, Marquette County Ontonagon counties Anhydrite, Bay, Berrien, Gratiot, Houghton, Babingtonite, Keweenaw County Isabella, Kalamazoo, Kent, Keweenaw, Macomb, Manistee,
    [Show full text]
  • Identification Tables for Common Minerals in Thin Section
    Identification Tables for Common Minerals in Thin Section These tables provide a concise summary of the properties of a range of common minerals. Within the tables, minerals are arranged by colour so as to help with identification. If a mineral commonly has a range of colours, it will appear once for each colour. To identify an unknown mineral, start by answering the following questions: (1) What colour is the mineral? (2) What is the relief of the mineral? (3) Do you think you are looking at an igneous, metamorphic or sedimentary rock? Go to the chart, and scan the properties. Within each colour group, minerals are arranged in order of increasing refractive index (which more or less corresponds to relief). This should at once limit you to only a few minerals. By looking at the chart, see which properties might help you distinguish between the possibilities. Then, look at the mineral again, and check these further details. Notes: (i) Name: names listed here may be strict mineral names (e.g., andalusite), or group names (e.g., chlorite), or distinctive variety names (e.g., titanian augite). These tables contain a personal selection of some of the more common minerals. Remember that there are nearly 4000 minerals, although 95% of these are rare or very rare. The minerals in here probably make up 95% of medium and coarse-grained rocks in the crust. (ii) IMS: this gives a simple assessment of whether the mineral is common in igneous (I), metamorphic (M) or sedimentary (S) rocks. These are not infallible guides - in particular many igneous and metamorphic minerals can occur occasionally in sediments.
    [Show full text]
  • Synthesis and Growth of Fresnoite (Ba2tisi2o8)
    JOURNAL OF RESEARC H of the Notionol Bureau of Sta ndards - A. Physics and Chemistry Vol. 74A, Na. 2, March- April 1970 ) Synthesis and Growth of Fresnoite (Ba 2TiSi 20 S) from a Ti0 2 Flux and Its Relation to the System BaTi0 3-Si0 2 > C. R. Robbins Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234 > (December 4, 1969) Crystals of Ba2 Ti Si,O. (syntheti c fresnoite) up to 5 mm in longest dimension have been grown by slow cooling of a TiO" ri ch liquid of initial composition IBaO : ITiO, : lSiO, . The syntheti c crystals are essentially identi cal to th eir mineral equivalent in morphology, cleavage, optical properties and unit cell dimension s. X·ray powder diffraction data previously reported for th e compound BaTiSiO.-, ("barium sphene") is that of Ba, TiSi, O •. Apparently th e compound BaTiS iO ., has never been syn ­ thesized and the system BaTiO,,-SiO, is not binary. Key word s: Ba,TiSi,0 8; BaTiSiO.-,; crystal growth; fresnoite; phosph or; pi ezoelectri c; system BaTiO,, -SiO,; TiO, solvent. 1. Introduction Table 1. X -ray and opticaL crystallographic data for fresnoite (Ba, Ti Si2 0 . ) a Crystals of Fresnoite (Ba2 TiSi 2 0 8) were found by Alfors, Stinson, Matthews, and Pabst [J] 1 in a study of the minerals of eastern Fresno County, California. X-RAY DATA /' The mineral occurs as subhedral to euhedral tetragonal I crystals, elongated slightly in the [001] direction, with System: Tetragonal forms {001}, {1l0} and one distinct cleavage, (001). Space Group: P4/mbn, P4bm or P4b2 Composition was established [1] to be Ba2TiSi2 0 g Unit Cell: a = 8.52 ± 0.01 A, c = 5.210 ± 0.005 A with traces of impurities by arc emission spectro­ c/a = 0.611 5 graphic analyses.
    [Show full text]
  • Petrography of Refractory Inclusions in CM2.6 QUE 97990 and the Origin of Melilite- Free Spinel Inclusions in CM Chondrites
    Petrography of refractory inclusions in CM2.6 QUE 97990 and the origin of melilite- free spinel inclusions in CM chondrites Item Type Article; text Authors Rubin, A. E. Citation Rubin, A. E. (2007). Petrography of refractory inclusions in CM2. 6 QUE 97990 and the origin of melilitefree spinel inclusions in CM chondrites. Meteoritics & Planetary Science, 42(10), 1711-1726. DOI 10.1111/j.1945-5100.2007.tb00532.x Publisher The Meteoritical Society Journal Meteoritics & Planetary Science Rights Copyright © The Meteoritical Society Download date 25/09/2021 23:03:04 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/656338 Meteoritics & Planetary Science 42, Nr 10, 1711–1726 (2007) Abstract available online at http://meteoritics.org Petrography of refractory inclusions in CM2.6 QUE 97990 and the origin of melilite-free spinel inclusions in CM chondrites Alan E. RUBIN Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095–1567, USA E-mail: [email protected] (Received 16 January 2007; revision accepted 08 April 2007) Abstract–Queen Alexandra Range (QUE) 97990 (CM2.6) is among the least-altered CM chondrites known. It contains 1.8 vol% refractory inclusions; 40 were studied from a single thin section. Inclusion varieties include simple, banded and nodular structures as well as simple and complex distended objects. The inclusions range in mean size from 30 to 530 μm and average 130 ± 90 μm. Many inclusions contain 25 ± 15 vol% phyllosilicate (predominantly Mg-Fe serpentine); several contain small grains of perovskite. In addition to phyllosilicate, the most abundant inclusions in QUE 97990 consist mainly of spinel-pyroxene (35%), followed by spinel (20%), spinel-pyroxene-olivine (18%), pyroxene (12%), pyroxene-olivine (8%) and hibonite ± spinel (8%).
    [Show full text]
  • Nomenclature of Common Metamorphic Rocks
    Appendix Nomenclature of Common Metamorphic Rocks Magmatic rocks are usually named after some locality. Only in rare cases does the rock name give any indication about the fabric and min­ eralogical composition of the rock. The names of magmatic rocks have to be memorized like words of a foreign language. Fortunately, this dif­ ficulty is not encountered in the nomenclature of most metamorphic rocks. It is only necessary to leam a few names of rock groups, which are characterized by a certain fabric andJor mineralogical composition. Furthermore, the presence of the main or critical minerals is indicated by placing their names in front of the group name. For instance, there is the group of marbles, all of which contain well-crystallized carbonates as their main constituent. A particular marble may be designated as dolomite marble, diopside-grossularite marble, tremolite marble, etc. Thus, the nomenclature of most metamorphic rocks is clear and easily understood. A more elaborate nomenclature based on quantitative mineralogical composition was proposed by Austrian petrographers after a discussion with colleagues from other countries. 1 This nomenclature is recommend­ able and is to a large extent adopted here. Names of Important Rock Groups Phyllite. Fine-grained and very finely schistose rock, the platy min­ erals of which consist mainly of phengite. Phengite sericite gives an overall silky sheen to the schistosity planes. The grain size is coarser than in slates but finer than in mica schists. '''Ein Vorschlag zur quantitativen und qualitativen Klassifikation der kristallinen Schiefer" (a symposium). Neues Jahrb. Minerals Monatsh.: 163-172 (1962). Nomenclature of Common Metamorphic Rocks 341 In phyllites the amount of phyllosilicates (phengite + some chlorite ± biotite) exceeds 50%.
    [Show full text]