DOCSLIB.ORG

Structures of Biological Minerals in Dental Research

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Structures of Biological Minerals in Dental Research Volume 106, Number 6, November–December 2001 Journal of Research of the National Institute of Standards and Technology [J. Res. Natl. Inst. Stand. Technol. 106, 1035–1044 (2001)] Structures of Biological Minerals in Dental Research Volume 106 Number 6 November–December 2001 Mathai Mathew and Shozo Takagi Structural features of some calcium phos- for the epitaxial, interlayered mixtures phates of biological interest are de- formed by these compounds and the in situ American Dental Association scribed. Structure of hydroxyapatite conversion of OCP to OHAp. Possible Health Foundation, (OHAp), considered as the prototype for roles of OCP in biological mineralization Paffenbarger Research Center, the inorganic component of bones and teeth are discussed. is discussed with respect to the kinds and National Institute of Standards and locations of ionic substitutions. Octacalcium Key words: biominerals; calcium phos- Technology, phosphate (OCP), is a probable precursor phates; crystal structure; fluorapatite; Gaithersburg, MD 20899-0001 in biological mineralization. OCP has a glaserite; hydroxyapatite; octacalcium USA layer type structure, with one layer quite phosphate. similar to that of OHAp and the other, a hydrated layer consisting of more widely Accepted: August 22, 2001 [email protected] spaced Ca, and PO4 ions and the water [email protected] molecules. The closeness of fit in the ap- atitic layers of OCP and OHAp accounts Available online: http://www.nist.gov/jres 1. Introduction The crystallography program at the American Dental found under physiological conditions, but are commer- Association Health Foundation, Paffenbarger Research cially important as components in fertilizers. Center, was initiated in the early 1970s. The program was designed to investigate the crystal structures of bio- logical minerals and related compounds associated with 2. Discussion—Calcium Phosphates or with potential bearing in mineralization processes. Since calcium phosphates comprise the largest group of The known pure calcium phosphates have been clas- biominerals in vertebrate animals, most of the work sified into three major structural types [1]: (i) the apatite carried out, was centered on or around calcium phos- type, Ca10(PO4)6X2, which includes the derivatives of phates or related materials. Crystal structures of a num- hydroxyapatite (X = OHϪ) and fluorapatite (X = FϪ)as ber of pyrophosphates, carbonates, bisphosphonates, well as those related to apatite-type structures such as and highly hydrated phosphates and arsenates of cal- octacalcium phosphate (OCP), [Octacalcium bis(hydro- cium, magnesium and strontium were also investigated. genphosphate) tetrakis(phosphate) pentahydrate], This review will summarize the structural features of Ca8(HPO4)2(PO4)4и5H2O and tetracalcium phosphate calcium phosphates relevant to biomineralization. The (TTCP), Ca4(PO4)2O; (ii) the glaserite type, which can 2Ϫ 3Ϫ phosphates containing HPO4 and PO4 generally con- be considered to include all polymorphs of tricalcium stitute the biologically relevant calcium phosphates. phosphates (TCP), Ca3(PO4)2; and (iii) the Ca-PO4 Ϫ Phosphates with only H2PO4 ions are not normally sheet-containing compounds, which include dicalcium 1035 Volume 106, Number 6, November–December 2001 Journal of Research of the National Institute of Standards and Technology phosphate dihydrate (DCPD), CaHPO4и2H2O, dical- cium phosphate anhydrous (DCPA), CaHPO4,and monocalcium phosphates, Ca(H2PO4)2иH2Oand Ca(H2PO4)2. A number of highly hydrated phosphatic compounds have been included as a new type of calcium phosphate [1], struvite-type structures, after the biomin- eral struvite, Mg(NH4)PO4и6H2O, although these com- pounds do not represent pure calcium phosphates. Amorphous calcium phosphate (ACP), a possible pre- cursor to bioapatite, may be related to one or more of the structural types discussed above. 2.1 Apatite Type Structures Apatites are a structural type for compounds of the general formula M10(XO4)6Y2 rather than specific com- pounds. In general, they are known to be capable of accommodating a wide variety of modifications and combinations of substitutions of ions and groups within Fig. 1. Crystal structure of FAp or hexagonal OHAp projected down the c-axis. The corners of the unit cell (marked by shaded circles) are the apatitic lattice. However, the term “apatite” has been occupied by FϪ in FAp and by OHϪ in OHAp. An alternate choice of extensively and synonymously used to represent the cal- unit cell is identified as a' and b'. Ϫ Ϫ cium phosphates, Ca10(PO4)6X2, where X = F ,OH ,or Ϫ Cl and this concept will be followed in this review. occupy 6h positions similar to the Ca2 ions, in expanded Apatites are thermodynamically the most stable phases triangular positions. Adjacent Ca1 and Ca2 polyhedra 3Ϫ among the calcium phosphates and, therefore, can be are linked through oxygen atoms of the PO4 tetrahe- considered as the probable end product in many reac- dra. Because of the crystallographic mirror symmetry tions. imposed by the space group, each OHϪ ion has to be considered at statistically disordered positions (4e) both 2.1.1 Hydroxyapatite above and below the mirror planes at z = 1/4 and 3/4. It has been shown by neutron diffraction studies [2] that Hydroxyapatite (OHAp), Ca10(PO4)6(OH)2, is used as the oxygen atoms in hydroxide ions are 0.34 Å away a model for inorganic component of bones and teeth. from the mirror plane with the OHϪ direction pointing However, apatites as they occur in biological tissues, away from the mirror planes. An averaged structure mineral formations and laboratory products can incor- could imply that in approximately half the unit cells the porate a wide variety of impurities and are seldom found OHϪ ions are pointed upward from the mirror plane and in pure stoichiometric form. in the remaining unit cells they are pointed downward. The most common form is hexagonal and the crystal However, this statistical disordering need not be com- structure has been described in the space group P63/m pletely random. At least some short range ordering is to (No. 176) with lattice parameters a = b = 9.432 Å and be invoked such as OH-OH-OH...HO-HO. The reversal c = 6.881 Å, Z = 1 [2]. The structure is depicted in Fig. of the OHϪ direction can be achieved by replacement of 1. The 10 Ca2+ ions occupy two crystallographically an OHϪ by FϪ or ClϪ etc. or by a vacancy. Thus, the different symmetry sites, 4f and 6h.FourCa2+ ions (4f) hexagonal OHAp is probably never strictly stoichiomet- are located in columns along the three-fold axes at 1/3, ric. 2/3, 0 and 2/3, 1/3, 0 separated by approximately one- Stoichiometric OHAp has been described as mono- half of the c-axis. These are commonly referred to as clinic, space group P21/b having cell parameters Ca1 (or column Ca). Ca1 is coordinated to nine O a = 9.4214(8) Å, b =2a, c = 6.8814(7) Å, ␥ = 120Њ, atoms, with six shorter bonds that define an approxi- with twice as many formula units per unit cell as in the mate trigonal prism and three longer bonds capping the hexagonal unit [3]. The structure is closely related to prism faces. The Ca-O9 polyhedra share the trigonal that of the hexagonal form, but with no restrictions 2+ 3Ϫ faces to form chains parallel to the c-axis. The remain- imposed by the mirror symmetry. The Ca and PO4 ing six Ca2+ ions (6h sites, referred to as Ca2 or triangu- ions occupy similar positions as in the hexagonal form. lar Ca) form two triangular sets at z = 1/4 and 3/4 on the However, the OHϪ ions are located in two different mirror planes. The Ca2 ions are seven-coordinated, with columns. Within each column all the OHϪ ions have the Ϫ 3Ϫ six O atoms and one OH ion. The six PO4 ions same direction of displacements from z = 1/4 as in the 1036 Volume 106, Number 6, November–December 2001 Journal of Research of the National Institute of Standards and Technology Ϫ 2Ϫ hexagonal form. All the OH ions in one column point stitially. Both HPO4 , and structurally incorporated wa- upward, while those in the other column point down- ter occur in some synthetic and biological apatites, but ward. Thus, there is no disordering of the OHϪ ions in their structural locations are not known. the monoclinic form. The monoclinic form is formed only under favorable thermal conditions. ؊ 2.1.4.1 X Ion Substitution The XϪ ion positions in apatites or the “X ion chan- 2.1.2 Fluorapatite nels”, as they are often referred to, appear to be the sites Ϫ Fluorapatite (FAp), Ca10(PO4)6F2, is the most stable of a great deal of interesting activity in apatites. The X among the apatites. FAp is hexagonal with the space ion positions in apatites are substituted by a variety of Ϫ Ϫ Ϫ 2Ϫ group P63/m and lattice parameters, a = b = 9.367(1) Å ions, frequently by OH ,F ,andCl , but also by CO3 and c = 6.884(1) Å, Z = 1 [4]. The positions of the two and O2Ϫ, or by vacancies or any combination of these. In 2+ 3Ϫ Ϫ sets of Ca ions and the PO4 ions are nearly identical pure form each X ion takes up its own particular loca- to those of OHAp. However, the FϪ ions occupy the tion, as noted above. However, when two or more of center of the Ca2 triangles (6h positions), on the mirror these ions are present at the same time, they interact planes at z = 1/4 and 3/4. with each other to produce effects not predicted from the knowledge of the structures of the end-member alone [5,7,8]. The positional z-parameters of the XϪ 2.1.3 Chlorapatite ions are shifted from their normal positions in the pure Chlorapatite (ClAp), Ca10(PO4)6(Cl)2, has been de- form, but the effects are more pronounced when the Ϫ scribed in the hexagonal space group P63/m, with cell larger Cl ions are involved.
Load more

Recommended publications
  • DESCRIPTIVE HUMAN PATHOLOGICAL MINERALOGY 1179 but Still Occursregularly
    Amerkan Mincraloght, Volume 59, pages I177-1182, 1974 DescriptiveHuman Pathological Mineralogy Rrcneno I. Gmsox P.O. Box I O79, Dauis,C alilornia 95 6 I 6 Absfract Crystallographic, petrographic, and X-ray powder difiraction analysis of approximately 15,000 samples showed that the most common mineral constituents of human pathological concretions are calcium oxalates (whewellite and weddellite), calcium phosphates (apatite, brushite, and whitlockite), and magnesium phosphates (struvite and newberyite). Less are monetite, hannayite, calcite, aragonite, vaterite, halite, gypsum, and hexahydrite."o-rnon of the variables determining which minerals precipitate, the effects of different pH values on deposi- tional conditions are most apparent, and are shown by occurrences and relationships among many of the minerals studied. A pH-sensitive series has been identified among magnesium phosphatesin concretions. Introduction The study was carried out over a period of three The importanceof mineralogyin the field of medi- years.Composition was confirmedby X-ray powder cine lies in the applicationof mineralogicalmethods diffraction and polarizing microscopy;sequence was to study pathologicalmineral depositsin the human arrived at from considerationsof microscopic tex- body. Urology benefitsgreatly becauseconcretions tural and crystallographicrelationships. More than of mineral matter (calculi) are common in the 14,500samples were derivedfrom the urinary sys- urinary system.The value of mineralogicalanalysis tem of kidneys,ureters, bladder, and urethra; the of urinary material was first describedby prien and remaining samples are not statistically significant Frondel (1947). Mineralogistsmay be unawareof and arediscussed only briefly. the variability and nature of such compounds be- Calcium cause reports are usually published in medical Oxalates journals. This investigationreports the mineralogy Whewellite, CaCzOE.H2O,and weddellite, CaCz- and possiblepathological significanceof these min- O4'2H2O,are very uncommonin the mineralworld.
    [Show full text]
  • Polarized Infrared Reflectance Spectra of Brushite
    Polarized infrared reflectance spectra of brushite (CaHPO4 center dot 2H(2)O) crystal investigation of the phosphate stretching modes Jean-Yves Mevellec, Sophie Quillard, Philippe Deniard, Omar Mekmene, Frederic Gaucheron, Jean-Michel Bouler, Jean-Pierre Buisson To cite this version: Jean-Yves Mevellec, Sophie Quillard, Philippe Deniard, Omar Mekmene, Frederic Gaucheron, et al.. Polarized infrared reflectance spectra of brushite (CaHPO4 center dot 2H(2)O) crystal investigation of the phosphate stretching modes. Spectrochimica Acta Part A: Molecular and Biomolecular Spec- troscopy, Elsevier, 2013, 111, pp.7. 10.1016/j.saa.2013.03.047. hal-00980658 HAL Id: hal-00980658 https://hal.archives-ouvertes.fr/hal-00980658 Submitted on 29 May 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. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 111 (2013) 7–13 Contents lists available at SciVerse ScienceDirect Spectr ochimica Acta Part A: Molecul ar and Biomo lecular Spectrosco py journal homepage: www.elsevier.com/locate/saa Polarized infrared reflectance spectra of brushite (CaHPO4Á2H2O) crystal investigation of the phosphate stretching modes ⇑ Jean-Yves Mevellec a, , Sophie Quillard b, Philippe Deniard a, Omar Mekmene c, Frédéric Gaucheron c, Jean-Michel Bouler b, Jean-Pierre Buisson a a CNRS, Institut des Matériaux Jean-Rouxel (IMN) – UMR 6502, Université de Nantes, 2 rue de la Houssinière, B.P.
    [Show full text]
  • Ammonium Phosphate on Gypsum
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by AMS Acta - Alm@DL - Università di Bologna HMC 2016 4 th Historic Mortars Conference Preliminary study on the use of ammonium phosphate for the conservation of marble-imitating gypsum-stuccoes Enrico Sassoni 1, Gabriela Graziani 2, George W. Scherer 3 and Elisa -ranzoni 4 0Tmh dqrhsxneAnknfm+)skx+ [email protected] 1Tmh dqrhsxneAnknfm+)skx+ faqhdk-fqyhmh1.tmhan-hs 2 OqhmbdsnmTmh dqrhsx+MI+TR@+ rbgdqdq.oqhmbdsnm-dct 0 Tmh dqrhsxneAnknfm+)skx+ dkhr-eqmynmh.tmhan-hs Abstract6 In this study, a novel method for consolidation and im rovement of resistance to water of gy sum-stuccoes was reliminarily investigated. The idea is treating gy sum with an aqueous solution of diammonium hydrogen hos hate (DAP, (.H 4)2HPO 4) to form hydroxya atite (HAP, Ca 10 (PO 4)6(OH) 2), which has much lower solubility than gy sum. Tests carried out on gy sum aste sam les, manufactured to resemble historic stuccoes, showed that, after treatment with the DAP solution, a significant im rovement in mechanical ro erties was achieved and brushite (CaHPO 4ì2H 2O) was formed (alongside some other by- roducts, that can be removed by an additional oultice treatment). Even if brushite is more soluble than HAP, still its formation is ex ected to be beneficial for stuccoes conservation, as brushite is significantly less soluble than gy sum. Introduction Since antiquity, gy sum-based stuccoes have been frequently used to imitate recious white or colored marbles, when the use of real marbles was not ossible, because trans ort from faraway quarries was too costly a1,2b.
    [Show full text]
  • Water Soluble Salts in Degradation Processes of Stony Architectural Monuments in the Upper Silesia
    Geological Quarterly, 1998,42 (2): 209-220 Water soluble salts in degradation processes of stony architectural monuments in the Upper Silesia Malgorzata LABUS Labus M. (1998) - Woter soluble sails in dcgrndation processes of stony nrchiteehuui monuments in the Upper Silcsia. Geol. Quill1., 42 (2): 209-220. WnrsUlwa. The study goals were aimed 111 obtaining infonnation on corrosion products of rocks used in architectural monuments in the Upper Silesia. Samples from four monume ntal buildings located 01 margins of the Upper Silesia were IlSCd in the study. Three of them nrc located in the western pill1 of the region: a castle at Tasuk, a grain elcvatorat Stare Gliwice and castle ruins III Chud6w, and one is located in the eastern part (a cn.~ tle 01 6(;dzill). Samples of rocks from area significantl y lcss affected by atmospheric COlltnmillDtion (castle ruins at MimII' in the 1um Kmkowsko..czC5tochowska region) were analp.ed for comparison. Samples of sandstone, limestone and granitoids were analY1.ed with X-ray dirfraCLornetry and microstructurnlll1lalyscs. Cnemical analyses were conducted for aqucOllS solutioos of powdered rock samples. The following compounds wert detected in the sltJdicd snmples: sulphates, chlorides, nitrntes and carbonates. Total snUnilY in the samples of sandstone lind limcslone Wll.~ calculated, based on the resulls ofche mical analyses and X-my difCractolTlCtry . The highest salinity was detected in the samples from lhe castle ruins al Chud6w. Mu/gunil/U LahU.f, Irmifu/e ofAppli ed Geology, Silesilln Tu/micul University, Akodemicko 2, 44- /00Gliwice. Poland (reuived: 3.02./998; ocupltd; 22.02.1998). Key words: Upper Silesia, architectural monuments, air pollution, building stone detcriOl1ltion, wfttersoluble salts.
    [Show full text]
  • Role of Strontium on the Crystallization of Calcium Hydrogen Phosphate Dihydrate (CHPD)
    Journal of Minerals & Materials Characterization & Engineering , Vol. 10, No.7, pp.625-636, 2011 jmmce.org Printed in the USA. All rights reserved Role of Strontium on the Crystallization of Calcium Hydrogen Phosphate Dihydrate (CHPD) K. Suguna 1, 2 , C. Sekar 3* 1 Department of Physics, Sri Sarada College for Women, Salem -636 016, TN, India. 2 Department of Physics, Periyar University, Salem- 636 011, TN, India. 3 Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi-630003, TN, India. *Corresponding Author: [email protected] ABSTRACT Calcium hydrogen phosphate dihydrate (CHPD, CaHPO 4· 2H2O) or brushite is found quite frequently in urinary calculi (stones) . Crystallization of brushite has been carried out in sodium metasilicate (SMS) gel with and without adding ‘Sr’ as additive. In pure system, dicalcium phosphate anhydrous (DCPA, CaHPO 4) or monetite and hydroxyapatite (HA, Ca 5(PO 4)3(OH)) grew along with brushite. The presence of Sr suppressed the formation of HA and enhanced the number and size of monetite crystals and changed the morphology of brushite crystals from needle shape to octopus-like shape. The samples were characterized by powder & single crystal X-ray diffraction (XRD), scanning electron microscopy (SEM), X- ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA) . Keywords: Brushite , Crystal growth, Sr additive, SEM. 1. INTRODUCTION Calcium phosphates have been studied extensively because of their occurrence in normal and pathological calcifications. Due to their excellent biocompatibility, it is a well-known bioactive material suitable for bone and hard tissue replacement [1] . Hydroxyapatite (HA, Ca 5(PO 4)3(OH), octacalcium phosphate (OCP,Ca 8H2(PO 4)6·5(H 2O)), tricalcium phosphate ( β- TCP, Ca 3(PO 4)2), dicalcium phosphate dihydrate or calcium hydrogen phosphate dihydrate (CHPD, CaHPO 4·2H 2O), dicalcium phosphate anhydrous (DCPA, CaHPO4), tetracalcium [2] phosphate (TTCP, Ca 4(PO 4)2O) and amorphous calcium phosphate (ACP) are different 625 626 K.
    [Show full text]
  • Bulletin 65, the Minerals of Franklin and Sterling Hill, New Jersey, 1962
    THEMINERALSOF FRANKLINAND STERLINGHILL NEWJERSEY BULLETIN 65 NEW JERSEYGEOLOGICALSURVEY DEPARTMENTOF CONSERVATIONAND ECONOMICDEVELOPMENT NEW JERSEY GEOLOGICAL SURVEY BULLETIN 65 THE MINERALS OF FRANKLIN AND STERLING HILL, NEW JERSEY bY ALBERT S. WILKERSON Professor of Geology Rutgers, The State University of New Jersey STATE OF NEw JERSEY Department of Conservation and Economic Development H. MAT ADAMS, Commissioner Division of Resource Development KE_rr_ H. CR_V_LINCDirector, Bureau of Geology and Topography KEMBLEWIDX_, State Geologist TRENTON, NEW JERSEY --1962-- NEW JERSEY GEOLOGICAL SURVEY NEW JERSEY GEOLOGICAL SURVEY CONTENTS PAGE Introduction ......................................... 5 History of Area ................................... 7 General Geology ................................... 9 Origin of the Ore Deposits .......................... 10 The Rowe Collection ................................ 11 List of 42 Mineral Species and Varieties First Found at Franklin or Sterling Hill .......................... 13 Other Mineral Species and Varieties at Franklin or Sterling Hill ............................................ 14 Tabular Summary of Mineral Discoveries ................. 17 The Luminescent Minerals ............................ 22 Corrections to Franklln-Sterling Hill Mineral List of Dis- credited Species, Incorrect Names, Usages, Spelling and Identification .................................... 23 Description of Minerals: Bementite ......................................... 25 Cahnite ..........................................
    [Show full text]
  • AFM Study of the Epitaxial Growth of Brushite (Cahpo4.2H2O) On
    American Mineralogist, Volume 95, pages 1747–1757, 2010 AFM study of the epitaxial growth of brushite (CaHPO4·2H2O) on gypsum cleavage surfaces ANDRÉ JORGE PINTO ,1 ENC A RN A CIÓN RUIZ -AGUDO ,2,* CHRISTINE V. PUTNIS ,2 ANDREW PUTNIS ,2 AM A LI A JIMÉNEZ ,1 A ND MA NUEL PRIETO 1 1Department of Geology, Universidad de Oviedo, Jesús Arias de Velasco s/n, 33005 Oviedo, Spain 2Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany ABSTR A CT The epitaxial overgrowth of brushite (CaHPO4·2H2O) by the interaction of phosphate-bearing, slightly acidic, aqueous solutions with gypsum (CaSO4·2H2O) was investigated in situ using atomic force microscopy (AFM). Brushite growth nuclei were not observed to form on the {010} gypsum cleavage surface, but instead formed in areas of high dissolution, laterally attached to gypsum [101] step edges. During the brushite overgrowth the structural relationships between brushite (Aa) and gyp- sum (A2/a) result in several phenomena, including the development of induced twofold twining, habit polarity, and topographic effects due to coalescence of like-oriented crystals. The observed brushite growth is markedly anisotropic, with the growth rate along the main periodic bond chains (PBCs) in the brushite structure increasing in the order [101] > [101] > [010], leading to tabular forms elongated on [101]. Such a growth habit may result from the stabilization of the polar [101] direction of brushite due to changes in hydration of calcium ions induced by the presence of sulfate in solution, which is 2– consistent with the stabilization of the gypsum [101] steps during dissolution in the presence of HPO4 ions.
    [Show full text]
  • AFM Study of the Epitaxial Growth of Brushite (Cahpo4.2H2O) On
    American Mineralogist, Volume 95, pages 1747–1757, 2010 AFM study of the epitaxial growth of brushite (CaHPO4·2H2O) on gypsum cleavage surfaces ANDRÉ JORGE PINTO ,1 ENC A RN A CIÓN RUIZ -AGUDO ,2,* CHRISTINE V. PUTNIS ,2 ANDREW PUTNIS ,2 AM A LI A JIMÉNEZ ,1 A ND MA NUEL PRIETO 1 1Department of Geology, Universidad de Oviedo, Jesús Arias de Velasco s/n, 33005 Oviedo, Spain 2Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany ABSTR A CT The epitaxial overgrowth of brushite (CaHPO4·2H2O) by the interaction of phosphate-bearing, slightly acidic, aqueous solutions with gypsum (CaSO4·2H2O) was investigated in situ using atomic force microscopy (AFM). Brushite growth nuclei were not observed to form on the {010} gypsum cleavage surface, but instead formed in areas of high dissolution, laterally attached to gypsum [101] step edges. During the brushite overgrowth the structural relationships between brushite (Aa) and gyp- sum (A2/a) result in several phenomena, including the development of induced twofold twining, habit polarity, and topographic effects due to coalescence of like-oriented crystals. The observed brushite growth is markedly anisotropic, with the growth rate along the main periodic bond chains (PBCs) in the brushite structure increasing in the order [101] > [101] > [010], leading to tabular forms elongated on [101]. Such a growth habit may result from the stabilization of the polar [101] direction of brushite due to changes in hydration of calcium ions induced by the presence of sulfate in solution, which is 2– consistent with the stabilization of the gypsum [101] steps during dissolution in the presence of HPO4 ions.
    [Show full text]
  • Cahpo4·2H2O) on the Gypsum Cleavage Surface
    American Mineralogist, Volume 94, pages 313–322, 2009 Interaction of phosphate-bearing solutions with gypsum: Epitaxy and induced twinning of brushite (CaHPO4·2H2O) on the gypsum cleavage surface ANDRÉ JORGE PINTO , AM A LI A JIMENEZ ,* A ND MA NUEL PRIETO Department of Geology, Universidad de Oviedo, Jesús Arias de Velasco s/n, 33005 Oviedo, Spain ABSTR A CT Under slightly acidic conditions and 25 °C, the interaction between phosphate-rich aqueous solu- tions and gypsum cleavage fragments results in the surface precipitation of brushite (CaHPO4·2H2O) crystals, which grow epitaxially on the (010) surface of gypsum. Using an A-centered unit-cell setting for both brushite (Aa) and gypsum (A2/a), the epitaxial relationship implies matching of the planes (010) of both structures and correspondence between equivalent crystallographic directions within these planes. The crystal habit of the overgrowing brushite is thin tabular to laminar on {010} with {111} and {111} as side faces and a clear elongation on [101]. There are two orientations of the brushite plates on the gypsum surface related to each other by a twofold axis on [010]. Thus, the overgrowth is an aggregate of parallel brushite crystals that may be twin-related, with the twofold axis as the twin law. During the interaction, gypsum dissolution is coupled with brushite growth until saturation with respect to both minerals is reached. A model of this thermodynamically driven dissolution-crystallization process is presented using the geochemical code PHREEQC. The epitaxial relationships are explained by comparing the bond system and the crystallographic properties of both minerals. Keywords: Phosphate, gypsum, epitaxy, twinning INTRODUCTION tracted considerable interest in recent years (e.g., Sainz-Díaz et al.
    [Show full text]
  • April 2005 Volume 5, Issue 1 February 2Th General Meeting
    Forward Diary 2005 April 2005 Volume 5, Issue 1 February 2th General Meeting PRESIDENT’S REPORT. April 6nd General Meeting nd 2 June 1 E=MC General Meeting August 3th ENERGY required = MASS of detailed planning x SPEED at which it must Annual General Meeting be done. th October 5 General Meeting This is the equation required to produce a seminar. I am pleased to report th that your committee is expending more than enough energy to produce the December 7 General Meeting required result. The planning for the 2005 Seminar is well on track. A very interesting two day program has been arranged, followed by a fascinating four day field trip and the release of an extensive and detailed publication on the minerals to be Newsletter Contents. found in the Kalgoorlie region. At our recent meeting Mr. Peter Downes, from the W.A.Museum, gave a President’s Report. very informative and entertaining PowerPoint presentation of the minerals Report by Mark Jacobson to be found in the Telfer area. Thank you Peter. on the Tucson Gem and It is sad to report that some members are well overdue with their annual Mineral Show subscriptions. I am sure that it is simply an oversight that will be rapidly Tucson, AZ, USA. rectified. Crystal Systems Guide. I look forward to seeing you all at our next meeting. NEW MEETING FORMAT. AJMSS 2005 Registration Forms. In response to some suggestions made by our members and after some Some Mineral Additions considerable debate at the last committee meeting. We have decided to revise To DR.
    [Show full text]
  • Apatite Biominerals
    minerals Review Apatite Biominerals Christèle Combes 1,*,†, Sophie Cazalbou 2,† and Christian Rey 1,† 1 CIRIMAT, Université de Toulouse, CNRS, INPT, UPS, ENSIACET, 4 allée Emile Monso, CS 44362, 31030 Toulouse cedex 4, France; [email protected] 2 CIRIMAT, Université de Toulouse, CNRS, INPT, UPS, Université Paul Sabatier, Faculté de Pharmacie, 35 Chemin des Maraichers, 31062 Toulouse cedex 9, France; [email protected] * Correspondence: [email protected]; Tel.: +33-534-32-34-09 † These authors contributed equally to this work. Academic Editors: Karim Benzerara, Jennyfer Miot and Thibaud Coradin Received: 30 December 2015; Accepted: 21 March 2016; Published: 5 April 2016 Abstract: Calcium phosphate apatites offer outstanding biological adaptability that can be attributed to their specific physico-chemical and structural properties. The aim of this review is to summarize and discuss the specific characteristics of calcium phosphate apatite biominerals in vertebrate hard tissues (bone, dentine and enamel). Firstly, the structural, elemental and chemical compositions of apatite biominerals will be summarized, followed by the presentation of the actual conception of the fine structure of synthetic and biological apatites, which is essentially based on the existence of a hydrated layer at the surface of the nanocrystals. The conditions of the formation of these biominerals and the hypothesis of the existence of apatite precursors will be discussed. Then, we will examine the evolution of apatite biominerals, especially during bone and enamel aging and also focus on the adaptability of apatite biominerals to the biological function of their related hard tissues. Finally, the diagenetic evolution of apatite fossils will be analyzed.
    [Show full text]
  • Precipitation Process of Calcium Phosphate from Calcium Carbonate Suspension Nayane Macedo Portela Silva, Fabienne Espitalier, Ange Nzihou
    Precipitation Process of Calcium Phosphate from Calcium Carbonate Suspension Nayane Macedo Portela Silva, Fabienne Espitalier, Ange Nzihou To cite this version: Nayane Macedo Portela Silva, Fabienne Espitalier, Ange Nzihou. Precipitation Process of Calcium Phosphate from Calcium Carbonate Suspension. KONA Powder and Particle Journal, Hosokawa Powder Technology Foundation, 2016, 33, pp.219-227. 10.14356/kona.2016002. hal-01620289 HAL Id: hal-01620289 https://hal.archives-ouvertes.fr/hal-01620289 Submitted on 5 Sep 2018 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. Precipitation Process of Calcium Phosphate from Calcium Carbonate Suspension † Nayane Macedo Portela da Silva, Fabienne Espitalier * and Ange Nzihou 1 Université de Toulouse, Centre RAPSODEE UMR CNRS 2392, France Abstract The Ca-HA is synthesized by reacting calcium carbonate (CaCO3) and ammonium dihydrogen orthophosphate (NH4H2PO4) in stoichiometric proportions. In this precipitation process, the ratio of Ca/P by moles is 1.67. The experiments were performed in a batch reactor at 25 °C. From control parameters, the pH and the temperature were measured in line for all experiments. The tests were performed with two liquid-solid mass ratios (H2O/ CaCO3) of 3 and 5.
    [Show full text]