DOCSLIB.ORG

Phase Transitions in the Series Boracite

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Phase Transitions in the Series Boracite 881 The Canad,ian Mineralo gist Vol. 34, pp. 881-892(1996) PHASETRANSITIONS IN THESERIES BORACITE- TREMBATHITE- GONGOLITE: PHASERELAflONS PETERC. BURNSTar.ll MICHAEL A. CARPENTER Department of Earth Sciences, University of Canbridge, Downing Steet, Cambridge CB2 3EQ, U.K. Ansrnq.cr The Sussex,New Brunswick,marine-evaporile-hosted borate deposits contain boracite-group minerals of the solid-solution seriesMgrBrOtrCl - FerBrO'.CI. Samplesof boracite,txembathite and congolite have beencharacterized by electron-probe microanalysisand by high-temperatureoptical examinationand X-ray powder diffraction. At 25oC,the orthorhombicboracite structure(PcA) is stablefor compositionsfrom MgrBrO,rCl to (Mgl.eFet.l)B?Ot3cl,and the rhombohedralcongolite structure(jR3c) occurs for compositionsranging from (Mg1.eFe1.1)B7O,uClto FerBrO,rCl. At high temperatures,all specimens examinedhave the cubic boracitestructure (F43c). Cooling resultsin a frst-order phasetransition to the orthorhombicstruc- ture, and specimenswith more than 36 mol.VoFerBrO,rCl undergoa further first-order phasetransition to the rhombohedral structure.The boundariesbetween the phaseswith cubic, orthorhombicand rhombohedralstructures are linear in composition- temperaturespace. There is a markeddiscontinuity in the unit-cell volume of specimensrich in Mg at the phasetransition from the cubic to the orthorhombicstructure; the positive volume strain is greatestin the Mg-rich samples.The high-temperature X-ray diffraction data show that the cubic-to-orthorhombicphase transition is frst order in samplesrich in Mg, but increasing Fe contentresults in a trend towaxdtricritical or second-ordercharacter. Higher Fe contentsare associatedwith a decreasein the absolutevalue of the volume strain due to the phasetransition. Although the symmetry-breakingstrain due to the phase transition is very small, it is revealed by the variation in peak width as a function of temperaturein the X-ray powder diffractograms. Keywords:boracite, trembathite, congolite, phase transition, phase relations, solid solution,mineral physics. SoNttu.a.rns l€s d6p6tsde boratede Sussex,au Nouveau-Brunswick,d'origine dvaporitiquemarine, contiennent des mindraux du groupe de la boracite,membres de la solutionsolide Mg3B7O,3Cl - FerBrOl3Cl.Nous avons caractdris6 les 6chantillonsde boracite, trembathiteet congolitepar analysei la microsonde6lectronique, par ex:rmendes propri6t6s optiques d tempdrature61ev6e, et par diffractionX. A25"C, la structurede la boraciteorthorhombique (Pca21) s'applique aux compositionsdans I'intervalle MgrBtO'rCl d (Mgr.eFer.r)B7Or,Cl,et la structurerhomboddrique de la congolite(R3c) s'appliqueaux compositionsdans I'intervalleentre (Mgr.nFer.r)B7ol3cl i FqBrO,rCl. A temp6rature6lev6e, tous les sp6cimens6tudi6s possbdent la strucfure de la boracitecubique (F43c). Un refroidissementcause une inversionde premier ordre i la structureorthorhombique; de plus, tout 6chantilloncontenant plus de 36To de Fe3BrO,,Cl (base molaire) subit une deuxidmetransition, a h structure rhombo6drique.les limites deschamps de stabilit6 desphases ayant les structurescubique, orthorhombique et rhombo6drique sont lin6aires dans un diagrammede composition versus temperature.Nous ddcelonsune discontinuit6importante dans le volume de la maille 6l6mentairedans le cas d'6chantillons riches en Mg en passantde la structurecubique h la structure orthorhombique;la distorsiondu r6seauassoci6e h la transitionest plus importantedans les dchantillonsles plus riches en Mg. Les donndesde diffraction X obtenuese rcmpdrature61ev6e montrent que cettetransition a un caractdrede premier ordre dans le cas d'6chantillonsriches en Mg, mais avecune augmentationen Fe, son caractdredevient tricritique ou de deuxibmeordre. lrs teneursplus 6lev6esen Fe mdnentd une diminution du degr6 de distorsion volumique due i l'inversion. La distorsion associ6ei l'inversion requisepour r6duire la sym6trieest trOsfaible; malgr6ceci, la largeurdes pics de diffraction en fonction de la temp6ratffeen est un reflet sensible. (Traduit par la R6daction) Mots-clds:boracite, trembathite, congolite, ffansition de phase,relations de phases,solution solide,physique min6rale. I Presentaddress: Department of Geology,University of lllinois at Urbana-Champaign,245Natural History Building, 1301 WestGreen Street, Urbana. Illinois 61801.U.S.A. 882 THE CANADIAN MINERALOGIST INTRoDUcTIoN specimens(due to these phasetransitions), and will illustrate how the microstructurerelates to the thermal Boracite-type phases have the general formula history of boratedeposits. M3B,OBX, whereM is a divalent cation (Mg, Cr, Mn, Most of the boracite-groupmineral specimens Fe, Co, Ni, Cu, Zn, Cd), and X is a halogen atom examined in this study are from the Penobsquis (Cl, Br, I). These phases have been synthetically evaporitedeposit, located in Sussex,New Brunswick. preparedand extensivelystudied, owing to the ferro- Since their discovery two decadesago, the marine- elastic, fenoelectric and magnetic properties of the evaporite-hostedborate deposits at Sussex have crystals Q.lelmes 1974). Five of the boracite-type received considerableattention (Roulston & Waugh phaseshave been describedas minerals (Table 1); all 1981, Rachfin et al. 1,986,Mandarino et al. 1990, have Cl as the halogen,and four containMg and Fe as Bums et al. 1992" Roberts et al. 1993. Gice et al. the divalent cation. Crystals of natural boracite-group 1994).The Mississippian-agedeposits occur in the mineralsusually containcomplex twinning anddisplay Windsor Group of the Moncton sub-basin,a part of anomalous optical properties, although some well- the northeasterly trending Fundy basin. Borate formed specimensshow excellent large domains. minerals are primarily located in the Upper Halite Schmid& Tippmann(1978) provided an interesting Memberfnomenclature of Roulston& Waugh(1983); historical overview of early studiesof boracite-group this is refened to as the Middle Halite Member by minerals. Roulston& Waugh (1981)1.Details of the geology The phasetransitions in boracite-typephases hpvp of the evaporite depositsmay be found in Roulston received a great deal oJ attention over the past three & Waugh (1983).In additionto a suite of a dozen decadesbecause of possible applications in the or more previously recognized borate mineral material sciences.For example,boracite-type phases species, mineralogical studies of these deposits have been considered as possible components for have led to the descriptions of the boracite-group optical page composers,optical storage,and passive mineral trembathite (Burns el al. 1992) and t}te display devices becausethey are ferroelecrics that CarBruO3a(OH)%C14.l3H2O polymorphs pringleite permit optical contrast upon switching (Schmid & and ruitenbergite (Roberts et al. 1993), whose Tippmann 1978). A necessaryrequirement for using structuresbear similarities to those of aluminosilicate boracite-typephases in this contextis the development zeolites(Gice et aI. 1994). of a composition having a very small shear angle The Zechsteinsalt depositsof Germanyalso contain in order to prevent cracking and various other boracite-gtoupminerals of a range of compositions. detrimental effects outlined by Schmid & Tippmann Heide& Vijlksch (1979)and Heide et aL (1980)have (1e78). examinedthe boratesin these deposits;their studies This study concernsphase relations in the series included chemical analyses, studies of crystal Mg3BrOtrCl - FerBTOrrCl.The seriesincludes the morphology by scanningelectron microscopy,X-ray minerals boracite [Mg3B7O13Cl], trembatlite diffraction, and differential thermal analyses. The [(Mg,Fe).BrO,rCl]and congolite[(Fe,Mg)rBrO13Cl]. Zechsteindeposits contain both well-formed pseudo- The structure of boracite is orthorhombic at room cubic crystals and fibrous intergrowths of boracite- temperature,whereas the structure of congolite is group minerals.Heide & Vdlksch (1979) indicated rhombohedral.Thus a solid-solution series between that the pseudocubiccrystals may have formed at Mg3B7Ol3Cland FqB7O13Clmust involve a phase several different times, and that intergrowths of transition. The purposeof this work is to characterize mimetic twins are absent. This absence of twins the phaserelations in this system,both as a function of indicatesthat the crystalsgrew in the stability field of Mg:Fe ratio and of temperature.In later contributions, the orthorhombicor rhombohedralstructure" and that a we will examine the microstructure in natural phasetransition has not occurred.Heide et al. (1980) reported chemical compositionsfor 21 specimensof boracite-groupminerals from the Zechsteindeposits. Crystal compositions range from end-member Mg3B7Ol3Clto (Fe2.54Mno.rnMgs.2)B7O13Cl. TABI.E 1. CELL DIMENSIONS OF BORACITE-GROUP1\4INENAT6 STRUCruRE AND PHASE TRANSITIONS Spae Grup o (A) o tAl c (b R€€ boracite-typephases boncit€ MgdrOn0l Pa2t 8.677(6) 8.668(8) 12.09(1) 1 The crystal structuresof all have cubic symmetry, space group F43c, at ht$ qi€ito (FeJVIglBzOrCl Po2: d.od d.oo \2.17 2 tr@bathite (Mg,Fe)rBrOuq A& 8.67q2) 20.99(1) 3 temperature.The structureof cubic boracite (Ito et al, mngoliie (Fe,Mg)gBrOrClE& 8.62.211) 21.064{6) 4 1951,Sueno et aL 1973)consists of a frameworkof chmbsite MnsB0rsgl Pw2t 8.68(1) 8.68(1) 12.26(1) 6 comer-sharing BO4 tetrahedra,with the metal and halogen atoms located within cavities in the borate MeM:(\)Bw (1996);(2)Kiiba& Schuc.ke(1966); (8)BlJruetal (1992); (4) Wentlliag et @l (19?2); (6) Hon@ & Beck (1962). framework(Frg. l). Using the descriptorof Burns el a/. TRANSITIONSIN BORACITE-GROIJPPHASES
Load more

Recommended publications
  • 1469 Vol 43#5 Art 03.Indd
    1469 The Canadian Mineralogist Vol. 43, pp. 1469-1487 (2005) BORATE MINERALS OF THE PENOBSQUIS AND MILLSTREAM DEPOSITS, SOUTHERN NEW BRUNSWICK, CANADA JOEL D. GRICE§, ROBERT A. GAULT AND JERRY VAN VELTHUIZEN† Research Division, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario K1P 6P4, Canada ABSTRACT The borate minerals found in two potash deposits, at Penobsquis and Millstream, Kings County, New Brunswick, are described in detail. These deposits are located in the Moncton Subbasin, which forms the eastern portion of the extensive Maritimes Basin. These marine evaporites consist of an early carbonate unit, followed by a sulfate, and fi nally, a salt unit. The borate assemblages occur in specifi c beds of halite and sylvite that were the last units to form in the evaporite sequence. Species identifi ed from drill-core sections include: boracite, brianroulstonite, chambersite, colemanite, congolite, danburite, hilgardite, howlite, hydroboracite, kurgantaite, penobsquisite, pringleite, ruitenbergite, strontioginorite, szaibélyite, trembathite, veatchite, volkovskite and walkerite. In addition, 41 non-borate species have been identifi ed, including magnesite, monohydrocalcite, sellaite, kieserite and fl uorite. The borate assemblages in the two deposits differ, and in each deposit, they vary stratigraphically. At Millstream, boracite is the most common borate in the sylvite + carnallite beds, with hilgardite in the lower halite strata. At Penobsquis, there is an upper unit of hilgardite + volkovskite + trembathite in halite and a lower unit of hydroboracite + volkov- skite + trembathite–congolite in halite–sylvite. At both deposits, values of the ratio of B isotopes [␦11B] range from 21.5 to 37.8‰ [21 analyses] and are consistent with a seawater source, without any need for a more exotic interpretation.
    [Show full text]
  • Crystal Structure and Magnetic Properties of the New Zn1. 5Co1
    Crystal Structure and Magnetic Properties of the New Zn1.5Co1.5B7O13Br Boracite Roberto Escudero∗ and Francisco Morales Instituto de Investigaciones en Materiales, Universidad Nacional Aut´onoma de M´exico. A. Postal 70-360. M´exico, D.F., 04510 MEXICO.´ Marco A Leyva Ramirez Departamento de Qu´ımica, Centro de Investigaci´on y Estudios Avanzados del IPN. 07360, M´exico, D. F. Jorge Campa-Molina and S. Ulloa-Godinez C. Universitario de Ciencias Exactas e Ingenieras, Universidad de Guadalajara, Laboratorio de Materiales Avanzados Departamento de Electronica. 044840, Guadalajara, Jalisco. MEXICO.´ (Dated: August 29, 2021) arXiv:1106.5446v1 [cond-mat.mtrl-sci] 27 Jun 2011 1 Abstract New Zn1.5Co1.5B7O13Br boracite crystals were grown by chemical transport reactions in quartz ampoules, at a temperature of 1173 K. The crystal structure was characterized by X-ray diffraction. The crystals present an orthorhombic structure with space group Pca21, (No. 29). The determined cell parameters were: a = 8.5705(3)A,˚ b = 8.5629(3) A,˚ and c = 12.1198(4)A,˚ and cell volume, V = 889.45(5) A˚3 with Z = 4. Magnetic properties in single crystals of the new boracite, were determined. The Susceptibility-Temperature (χ−T ) behavior at different magnetic intensities was studied. The inverse of the magnetic susceptibility χ−1(T ) shows a Curie-Weiss characteristic with spin s = 3/2 and a small orbital contribution, l. At low temperatures, below 10 K, χ(T ) shows irreversibility that is strongly dependent on the applied magnetic field. This boracite is ferrimag- netic up to a maximum temperature of about 16 K, as shows the coercive field.
    [Show full text]
  • General Index
    CAL – CAL GENERAL INDEX CACOXENITE United States Prospect quarry (rhombs to 3 cm) 25:189– Not verified from pegmatites; most id as strunzite Arizona 190p 4:119, 4:121 Campbell shaft, Bisbee 24:428n Unanderra quarry 19:393c Australia California Willy Wally Gully (spherulitic) 19:401 Queensland Golden Rule mine, Tuolumne County 18:63 Queensland Mt. Isa mine 19:479 Stanislaus mine, Calaveras County 13:396h Mt. Isa mine (some scepter) 19:479 South Australia Colorado South Australia Moonta mines 19:(412) Cresson mine, Teller County (1 cm crystals; Beltana mine: smithsonite after 22:454p; Brazil some poss. melonite after) 16:234–236d,c white rhombs to 1 cm 22:452 Minas Gerais Cripple Creek, Teller County 13:395–396p,d, Wallaroo mines 19:413 Conselheiro Pena (id as acicular beraunite) 13:399 Tasmania 24:385n San Juan Mountains 10:358n Renison mine 19:384 Ireland Oregon Victoria Ft. Lismeenagh, Shenagolden, County Limer- Last Chance mine, Baker County 13:398n Flinders area 19:456 ick 20:396 Wisconsin Hunter River valley, north of Sydney (“glen- Spain Rib Mountain, Marathon County (5 mm laths donite,” poss. after ikaite) 19:368p,h Horcajo mines, Ciudad Real (rosettes; crystals in quartz) 12:95 Jindevick quarry, Warregul (oriented on cal- to 1 cm) 25:22p, 25:25 CALCIO-ANCYLITE-(Ce), -(Nd) cite) 19:199, 19:200p Kennon Head, Phillip Island 19:456 Sweden Canada Phelans Bluff, Phillip Island 19:456 Leveäniemi iron mine, Norrbotten 20:345p, Québec 20:346, 22:(48) Phillip Island 19:456 Mt. St-Hilaire (calcio-ancylite-(Ce)) 21:295– Austria United States
    [Show full text]
  • Assessment of the Molecular Structure of the Borate Mineral Boracite
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 96 (2012) 946–951 Contents lists available at SciVerse ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa Assessment of the molecular structure of the borate mineral boracite Mg3B7O13Cl using vibrational spectroscopy ⇑ Ray L. Frost a, , Yunfei Xi a, Ricardo Scholz b a School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, G.P.O. 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 " Boracite is a magnesium borate mineral with formula: Mg3B7O13Cl. " The crystals belong to the orthorhombic – pyramidal crystal system. " The molecular structure of the mineral has been assessed. " Raman spectrum shows that some Cl anions have been replaced with OH units. article info abstract Article history: Boracite is a magnesium borate mineral with formula: Mg3B7O13Cl and occurs as blue green, colorless, Received 23 May 2012 gray, yellow to white crystals in the orthorhombic – pyramidal crystal system. An intense Raman band Received in revised form 2 July 2012 À1 at 1009 cm was assigned to the BO stretching vibration of the B7O13 units. Raman bands at 1121, Accepted 9 July 2012 1136, 1143 cmÀ1 are attributed to the in-plane bending vibrations of trigonal boron. Four sharp Raman Available online 13 August 2012 bands observed at 415, 494, 621 and 671 cmÀ1 are simply defined as trigonal and tetrahedral borate bending modes. The Raman spectrum clearly shows intense Raman bands at 3405 and 3494 cmÀ1, thus Keywords: indicating that some Cl anions have been replaced with OH units.
    [Show full text]
  • Congolite and Trembathite from the Kłodawa Salt Mine, Central Poland: Records of the Thermal History of the Parental Salt Dome
    1387 The Canadian Mineralogist Vol. 50, pp. 1387-1399 (2012) DOI : 10.3749/canmin.50.5.1387 CONGOLITE AND TREMBATHITE FROM THE KŁODAWA SALT MINE, CENTRAL POLAND: RECORDS OF THE THERMAL HISTORY OF THE PARENTAL SALT DOME JACEK WACHOWIAK§ AGH – University of Science and Technology, Department of Economic and Mining Geology; al. Mickiewicza 30, 30-059 Kraków, Poland ADAM PIECZKA AGH – University of Science and Technology, Department of Mineralogy, Petrography and Geochemistry; al. Mickiewicza 30, 30-059 Kraków, Poland ABSTRACT Pseudocubic crystals of (Fe,Mg,Mn)3B7O13Cl borate, ≤ 1.2 mm in size and yellowish through pale-violet to pale-violet- brown and brownish in color, were found in the Kłodawa salt dome, located within the Mid-Polish Trough (central Poland), an axial part of the Polish basin belonging to a system of Permian-Mesozoic epicontinental basins of Western and Central Europe. The crystals occur in adjacent parts of the Underlying Halite and Youngest Halite units bordering the Anhydrite Pegmatite unit around the PZ–3/PZ–4 (Leine/Aller) boundary. The internal texture of the crystals reflects phase-transitions from rhombohedral congolite (space-group symmetry R3c) through orthorhombic ericaite (Pca21) to a cubic, high-temperature, mainly Fe-dominant analogue of boracite (F43c), indicating formation of the phases under increasing temperature. Currently, the parts of the crystals showing orthorhombic and cubic morphology generally represent congolite and, much less frequently, trembathite paramorphs after higher-temperature structural varieties of (Fe,Mg,Mn)3B7O13Cl and (Mg,Fe,Mn)3B7O13Cl, which are unstable at room- temperature. The phase-transitions R3c → Pca21 and Pca21 → F43c recorded in the morphology of the growing crystals took place at temperatures of 230–250 °C and 310–315 °C, respectively, whereas the total range of (Fe,Mg,Mn)3B7O13Cl borate crystallization was determined to be ca.
    [Show full text]
  • CHAMBERSITE, a NEW MINERAL Russrr-R- M. Honbe Ewp Fnenr R
    THE AMERICAN MINERAI,OGIST, VOL. 47, MAY JUNE, 1962 CHAMBERSITE, A NEW MINERAL Russrr-r- M. HoNBe ewp FneNr R. Bncr,l Department oJ Geology and.Mineralogy, Ltniaersityof Colorad.o,Bould,er, Colorailo anil Department.of Geology,Fort Hays Kansas State College, Hays, Kansas. ABSTRACT Chambersite is present in brine returns from a gas storage well on Barber's Hill salt dome, Chambers County, Texas. Crystals are almost colorless to deep purple, paramorphic isometric with the positive tetrahedron as the dominant form. H 7, G 3.49 (meas.),3.48 (calc.). No cleavage,fracture subconchoidalto uneven. Optically biaxial positive, a:t.732, A:1.737,7:I.7M+0.001, 2V:83o*30. Orthorhombic crystal aggregatesmake up para- morphs. Chemical analysis: MnO 41.87, FeO 1.28, MgO 0.05, CaO tr, BzOa49'50, Cl 6.34, remainder-1.39. Total 100.43 minus 0:Cl 1.39, corrected total99.04/e. The formuia is Mnz.goFeo.osMgo.orBzOrrClUnit cell of the low temperature dimorph is orthorhombic, a:8.68, b:8.68, c:12.26it; strongest lines of the r-ray powder pattern are (10) 3.07, (6) 2.74, (6) 2 08, (5) 3.54, (5) 2.17. Differential thermal analysis shows the orthorhombic- isometric inversion at 407" C. and melting at 1065o C. IwrnopucrroN AND OccunneNcB Chambersitewas first found in 1957in brine returns from a gasstorage well in the Barber's Hill salt dome, Chambers County, Texas. Pre- liminary data from optical examination and #-ray powder diffraction indicated the mineral to be related to boracite but distinctly different from any published descriptions.
    [Show full text]
  • A Specific Gravity Index for Minerats
    A SPECIFICGRAVITY INDEX FOR MINERATS c. A. MURSKyI ern R. M. THOMPSON, Un'fuersityof Bri.ti,sh Col,umb,in,Voncouver, Canad,a This work was undertaken in order to provide a practical, and as far as possible,a complete list of specific gravities of minerals. An accurate speciflc cravity determination can usually be made quickly and this information when combined with other physical properties commonly leads to rapid mineral identification. Early complete but now outdated specific gravity lists are those of Miers given in his mineralogy textbook (1902),and Spencer(M,i,n. Mag.,2!, pp. 382-865,I}ZZ). A more recent list by Hurlbut (Dana's Manuatr of M,i,neral,ogy,LgE2) is incomplete and others are limited to rock forming minerals,Trdger (Tabel,l,enntr-optischen Best'i,mmungd,er geste,i,nsb.ildend,en M,ineral,e, 1952) and Morey (Encycto- ped,iaof Cherni,cal,Technol,ogy, Vol. 12, 19b4). In his mineral identification tables, smith (rd,entifi,cati,onand. qual,itatioe cherai,cal,anal,ys'i,s of mineral,s,second edition, New york, 19bB) groups minerals on the basis of specificgravity but in each of the twelve groups the minerals are listed in order of decreasinghardness. The present work should not be regarded as an index of all known minerals as the specificgravities of many minerals are unknown or known only approximately and are omitted from the current list. The list, in order of increasing specific gravity, includes all minerals without regard to other physical properties or to chemical composition. The designation I or II after the name indicates that the mineral falls in the classesof minerals describedin Dana Systemof M'ineralogyEdition 7, volume I (Native elements, sulphides, oxides, etc.) or II (Halides, carbonates, etc.) (L944 and 1951).
    [Show full text]
  • Structural Studies of Ferroelectrics of The
    STRUCTURAL STUDIES OF FERROELECTRICS OF THE BORACITE AND KH P0 TYPE WILLIAM JOHN HAY DOCTOR OF PHILOSOPHY UNIVERSITY OF EDINBURGH 1978 The research described in this thesis was the unaided work of the author, unless otherwise indicated. Where the research was done in collaboration--with others, there was a significant contribution by the author. ACKNOWLEDGEMENTS I would like to express my gratitude to all those who have helped to make this work possible. In particular my personal thanks go to my supervisor Dr R J Nelmes for his guidance, assistance and encouragement. I am very grateful to Professors N Feather and W Cochran for extend- ing to me the facilities of the Department of Physics at Edinburgh University; to the Science Research Council for granting me access to the facilities of A.E.R.E., Harwell; to Professor Woolfson for extending to me the facilities of the Department of Physics at York University; and to Dr P Main of York University for his kindness and assistance. I would like to thank the Atomic Energy Authority for the award of a research studentship. Finally I would also like to thank the staff of A.E.R.E., Harwell for their kindness and assistance, my friends and colleagues at Edinburgh for their help and encouragement, Mrs P Wood for her patient and painstaking work in preparing this thesis and my wife and family for their unstinted encouragement and support. ABSTRACT This thesis is concerned with structural studies of ferroelectric crys- tals, in particular the structure of CsD 2AsO 4 in its tetragonal paraelec- tric phase and orthorhombic ferroelectric phase and the structures of Co 3B7O13 I and Cu 3B7O13Br in their cubic paraelectric phases.
    [Show full text]
  • Vibrational Spectroscopy of the Borate Mineral Chambersite Mnb7o13cl - Implications for the Molecular Structure
    This may be the author’s version of a work that was submitted/accepted for publication in the following source: Frost, Ray, Lopez, Andres, Scholz, Ricardo, & Xi, Yunfei (2014) Vibrational spectroscopy of the borate mineral chambersite MnB7O13Cl - Implications for the molecular structure. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 120, pp. 270-273. This file was downloaded from: https://eprints.qut.edu.au/65134/ c Consult author(s) regarding copyright matters This work is covered by copyright. Unless the document is being made available under a Creative Commons Licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. If the docu- ment is available under a Creative Commons License (or other specified license) then refer to the Licence for details of permitted re-use. It is a condition of access that users recog- nise and abide by the legal requirements associated with these rights. If you believe that this work infringes copyright please provide details by email to [email protected] License: Creative Commons: Attribution-Noncommercial-No Derivative Works 2.5 Notice: Please note that this document may not be the Version of Record (i.e. published version) of the work. Author manuscript versions (as Sub- mitted for peer review or as Accepted for publication after peer review) can be identified by an absence of publisher branding and/or typeset appear- ance. If there is any doubt, please refer to the published source. https://doi.org/10.1016/j.saa.2013.10.026 1 Vibrational spectroscopy of the borate mineral chambersite MnB7O13Cl 2 – Implications for the molecular structure 3 4 Ray L.
    [Show full text]
  • Kieserite Mgso4 • H2O C 2001-2005 Mineral Data Publishing, Version 1
    Kieserite MgSO4 • H2O c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Monoclinic. Point Group: 2/m. Crystals are uncommon, dipyramidal {111}, with {110} and perhaps another dozen forms, to 10 cm; typically coarse- to fine-grained, massive. Twinning: On {001}, contact; polysynthetic about [110]. Physical Properties: Cleavage: On {110}, {111}, perfect; on {111}, {101}, {011}, imperfect. Tenacity: Friable to firm. Hardness = 3.5 D(meas.) = 2.571 D(calc.) = 2.571 Slowly soluble in H2O. Optical Properties: Translucent. Color: Colorless, pale gray, pale yellow; colorless in transmitted light. Luster: Vitreous. Optical Class: Biaxial (+). Orientation: Y = b; Z ∧ c = –76.5◦. Dispersion: r> v,moderate. α = 1.520 β = 1.533 γ = 1.584 2V(meas.) = 55◦ Cell Data: Space Group: C2/c. a = 6.912(2) b = 7.624(2) c = 7.642(2) β = 118.09(2)◦ Z=4 X-ray Powder Pattern: Klodawa, Poland. (ICDD 13-102). 3.41 (10), 4.84 (9), 3.33 (9), 2.527 (9), 2.055 (9), 3.05 (8), 2.567 (8) Chemistry: (1) (2) SO3 57.93 57.85 MgO 29.00 29.13 H2O 13.07 13.02 Total 100.00 100.00 • (1) Stassfurt, Germany. (2) MgSO4 H2O. Mineral Group: Kieserite group. Occurrence: Typically in marine salt deposits; rarely as a volcanic sublimate or efflorescence. Association: Halite, carnallite, polyhalite, anhydrite, boracite, sulfoborite, leonite, epsomite, celestine. Distribution: In Germany, from the Stassfurt-Westeregeln district, with large crystals from the Bartensleben mine, Saxony-Anhalt; in the Hildesia mine, near Hannover, and at Wathlingen, Lower Saxony, and many other places.
    [Show full text]
  • Data of Geochemistry
    Data of Geochemistry * Chapter Y. Marine Evaporites GEOLOGICAL SURVEY PROFESSIONAL PAPER 440-Y Data of Geochemistry ' MICHAEL FLEISCHER, Technical Editor Chapter Y. Marine Evaporites By FREDERICK H. STEWART GEOLOGICAL SURVEY PROFESSIONAL PAPER 440-Y UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director REPRINTED 1964 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C., 20402 - Price 60 cents (paper cover) DATA OF GEOCHEMISTRY, SIXTH EDITION Michael Fleischer, Technical Editor The first edition of the Data of Geochemistry, by F. W. Clarke, was published in 1908 as U.S. Geological Survey Bulletin 330. Later editions, also by Clarke, were published in 1911, 1916, 1920, and 1924 as Bulletins 491, 616, 695, and 770. This, the sixth edition, has been written by several scientists in the Geological Survey and in other institutions in the United States and abroad, each preparing a chapter on his special field. The current edition is being published in individual chapters, titles of which are listed below. Chapters already published are indicated by boldface. CHAPTER A. The chemical elements B. Cosmochemistry C. Internal structure and composition of the Earth D. Composition of the earth's crust E. Chemistry of the atmosphere F. Chemical composition of subsurface waters, by Donald E. White, John D. Hem, and G. A. Waring G. Chemical composition of rivers and lakes, by Daniel A. Livingstone H. Chemistry of the oceans I. Geochemistry of the biosphere J. Chemistry of rock-forming minerals K. Volcanic emanations, by Donald E.
    [Show full text]
  • Winter 2002 Gems & Gemology
    Winter 2002 VOLUME 38, NO. 4 291 LETTERS _____________ FEATURE ARTICLES _____________ 294 Chart of Commercially Available Gem Treatments Christopher P. Smith and Shane F. McClure Provides a comprehensive, easy-to-use reference to the most common gem enhancements on the market today and their detectability. 301 Gemesis Laboratory-Created Diamonds James E. Shigley, Reza Abbaschian, and Carter Clarke pg. 308 A study of the jewelry-quality yellow synthetic diamonds being grown on a commercial scale by Gemesis Corp. of Sarasota, Florida. 310 Legal Protection for Proprietary Diamond Cuts Thomas W. Overton A guide to the protection of diamond cut designs through trademarks and patents. Includes a history of diamond cut patents and a review of proprietary designs currently in the marketplace. 326 Rhodizite-Londonite from the Antsongombato Pegmatite, Central Madagascar Brendan M. Laurs, Federico Pezzotta, William B. (Skip) Simmons, Alexander U. Falster, and Sam Muhlmeister pg. 319 Describes the history, geology, mining, and gemological characteristics of gem-quality rhodizite-londonite from its only known source. REGULAR FEATURES _______________________________ 340 Gem Trade Lab Notes • “Piranha” agate • Surface-treated amber • Unusual ceramic pearl simulant • More Be diffusion—rubies and orange sapphire • Diamond with internal inscriptions • Two large glass imitation jade carvings • Bleached, impregnat- ed, and dyed jadeite with unusual inclusions • Cultured pearls with treated yellow color 348 Gem News International • Kimberley Process ratified
    [Show full text]