DOCSLIB.ORG

A Systematic Approach to General and Structure-Type Formulas for Minerals and Other Inorganic Phases

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Systematic Approach to General and Structure-Type Formulas for Minerals and Other Inorganic Phases American Mineralogist, Volume 83, pages 126±132, 1998 A systematic approach to general and structure-type formulas for minerals and other inorganic phases DEANE K. SMITH,1 ANDREW C. ROBERTS,2 PETER BAYLISS,3 AND FRIEDRICH LIEBAU4 1Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802, U.S.A. 2Geological Survey of Canada, 762-601 Booth Street, Ottawa, Ontario K1A 0E8, Canada 3Mineralogy, Australian Museum, 6 College Street, Sydney, N.S.W. 2000, Australia 4Mineralogisch-Petrologisches Institut und Museum, der UniversitaÈt Kiel, Olshausenstrasse 40-60, 24098 Kiel, Germany ABSTRACT During the preparation of the Mineral Group List Index of the Mineral Powder Diffrac- tion File, it was necessary to develop a consistent scheme for the representation of the structural formulas. Because the fourteen letters B, C, F, H, I, K, N, O, P, S, U, V, W, and Y of the Latin (Roman) alphabet represent chemical elements (element symbols), this system uses twelve letters to represent cations, anions, and molecules occupying various sites of the structure (site symbols). The letters available as structure-site symbols represent cations with decreasing coordination numbers (CN) as follows: D,CN$ 9; E,CN5 8 or 7; G,CN5 6; J,CN5 5; Q,CN5 4 planar or 2 linear; T,CN5 4 tetrahedral; and R,CN5 3 planar. These de®nitions leave suf®cient remaining letters for other structure- site symbols such as: A for all cations without regard to the coordination number; L for lone-electron-pair cations; M for neutral molecular units; X for monatomic anions; and Z for polyatomic anions. Structure sites of the same coordination type, yet distinct enough for ordered occupancy of resident cations, may be differentiated by primes (9,99,999, etc.). Variable coordination numbers on a structure site and variable site occupancies are indi- cated by two symbols or subscripts with the intervening symbol ↔. For example, the general structure-type formula of amphibole may be written as A7↔8[T4X11]2X92. A speci®c structure-type formula also allows for a mixture of symbols to represent chemical elements ↔ and structure sites such as A0↔1(E9 G)2G93G992[Si4O11]2(OH)2 whereas an example of a chemical formula is Ca2Mg5[Si4O11]2(OH)2 for the amphibole tremolite. INTRODUCTION a structure site different from an equally unspeci®ed cat- During the preparation of the Mineral Group List Index ion A. for the Mineral Powder Diffraction File (Bayliss et al. The term mineral group has been used in many places 1993) produced by the International Center for Diffrac- (Strunz 1970; Bayliss et al. 1993; Fleischer and Manda- tion Data, the need arose for a consistent technique to rino 1995) without rigorous de®nition. For the Mineral represent structural formulas of the various mineral Powder Diffraction File, a mineral group is de®ned as a groups. An examination of the mineralogical and crystal- collection of three or more mineral species with X-ray chemical literature reveals many different methods used diffraction patterns that show marked similarities because to represent structural formula when discussing minerals the structures have considerable similarities, in particular and groups of minerals having the same or similar struc- regarding crystallographic sites, stoichiometric ratios of ture types.1 This lack of consistency leads to considerable their sites, and coordination of the elements occupying confusion. Additional confusion results from use of the these sites. As a consequence of such similarities, a gen- same letter in different ways, e.g., B in ABO3 to represent eral structure-type formula can be written for the mineral either a boron atom or an unspeci®ed cation that occupies group, which contains information on these common structural properties, e.g., homologous (polysomatic) se- 1 According to Lima-de-Faria et al. (1990), several structures ries such as humite, homeotypes such as perovskite, po- constitute a structure type if: (1) They have the same space-group lytypoids such as amphibole, polytypes such as kaolinite, type [as de®ned in International Tables for Crystallography (1992)] or belong to a pair of enantiomorphic space-group types; and isotypic series such as forsterite-faya1ite. A mineral (2) the atomic positions, occupied either fully or partially at ran- subgroup may be further de®ned as containing three or dom, are the same in both structures; (3) for all Wyckoff posi- more minerals within a group that have the same structure tions, both the crystallographic point con®gurations and their type as described by Lima-di-Faria et al. (1990). general geometrical interrelationships are similar; and (4) the cor- responding atoms and corresponding bonds have similar The extent of inconsistencies in structural formulas is characteristics. illustrated further by an examination of a few references 0003±004X/98/0102±0126$05.00 126 SMITH ET AL.: STRUCTURALLY BASED FORMULAS 127 in structural chemistry and mineralogy. Palache et al. A SYSTEMATIC APPROACH (1944, 1951) used AX, AX , and A X for simple sul®des, 2 2 3 Structural formulas in chemistry and mineralogy con- oxides, and halides regardless of the size of the atoms tain two types of symbols having different quality: (1) involved, the coordination number, and the valence on the symbols to represent atoms and structure sites and (2) atoms and structural formulas such as A B (XO ) Z for m n 4 p q symbols to indicate structure details. Here the term struc- more complex situations. Wells (1984) and Lima-de-Faria ture site is de®ned as a set of symmetry-equivalent points. (1994) used structural formulas such as ABCX and 3 These sites differ from Wyckoff positions used in the In- A BX for compounds based on close packings, also with- 2 4 ternational Tables for Crystallography (1992) by the fact out regard to the size, coordination number, and valence. that the coordinates, x, y, and z, of a structure site must Wyckoff (1965) used structural formulas such as be within a range that its points have the same de®nite R (M X ) . Strunz (1970) usually emphasized the main x n p y coordination number. Within the ®rst category of symbols structural unit(s) in structural formulas but did use RO 3 are element symbols and structure-site symbols. and RO4 where both atomic groups may occur in the same structure (as in the borates). Bloss (1971) used structural Symbols for atoms and structure sites formulas similar to Palache et al. (1944, 1951), i.e., AX and A X , with no distinction as to the site coordination, Element symbols. In scienti®c writing, chemical for- 2 3 mulas are constructed of the letters of the Latin (Roman) and ..ZnOm for the silicate groups. Muller and Roy (1974) followed Wells (1984), but made more distinction by us- alphabet regardless of the language used for the main ing A for tetrahedral sites and B for octahedral sites. text. Consequently, it is desirable to retain this alphabet Among mineralogical texts, Berry et al. (1983), Klein in any represention of structural formulas. Fourteen Latin and Hurlbut (1985), and Blackburn and Dennen (1988) letters individually represent elements: B, C, F, H, I, K, N, O, P, S, U, V, W, and Y. These symbols are henceforth all used XmYn(ZpOq)Wr as a silicate structural formula. Smith (1972) and Zoltai and Stout (1984) used M for called element symbols. They should not be considered octahedral sites and T for tetrahedral sites. Deer et al. available as structure-site symbols. Structure-site symbols. The letters A, D, E, G, J, L, (1963) employed XYZ2O6 and WX2Y5Z8(OH)2 for pyrox- ene and amphibole, respectively; whereas Putnis (1992) M, Q, R, T, X, and Z are available for representation of sites in the structure and the species occupying them. To used ABSi2O6 and A0 2 1B2C5T8O22(OH3F)2, respectively, to make comparisons of pyroxene and amphibole easier distinguish further the structure-site symbols, the letters 2 and used similar structural formulas for other silicate are represented best using a different font (bold) but it is not necessary because the letters are unique. The letters groups. Fleischer and Mandarino (1995) used ABZ2O6 for pyroxene and A B Y Z O (OH) for amphibole, (structure-site symbols) are utilized in a systematic fash- 0 2 1 2 5 8 22 2 ion in which each letter represents speci®c sites in the whereas AB(CO3)2 is used for the dolomite group. These few examples show that there is no systematic structure characterized by coordination and, indirectly, by usage of symbols for structural formulas. X and Z are the size of the occupying ions. The type of structure-site used for both cation and anion structure sites. The same symbol will then suggest the elements that will usually structural site is described by different letters (A, B, M, substitute on that site. The various structure-site symbols and X for octahedral sites; A, R, T, and Z for the tetra- are de®ned below. hedral sites) by different authors. Some letters have dou- To minimize deviation from some of the older usage ble meanings: B, C, W, and Y are used for structure sites indicated in the introduction and to provide a systematic and as element symbols for boron, carbon, tungsten, and usage, the early letters of the alphabet are assigned to yttrium. In addition to generating confusion, these ex- sites in the structure occupied by the larger cations. The amples offer no suggestion for a universally accepted ap- later letters are assigned for those sites occupied by the proach for writing structural formulas. Unfortunately, smaller cations and also to those occupied by anions. This these examples are only a representation of the techniques set of de®nitions retains familiar associations such as T used in technical articles and other references.
Load more

Recommended publications
  • Unusual Silicate Mineralization in Fumarolic Sublimates of the Tolbachik Volcano, Kamchatka, Russia – Part 2: Tectosilicates
    Eur. J. Mineral., 32, 121–136, 2020 https://doi.org/10.5194/ejm-32-121-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Unusual silicate mineralization in fumarolic sublimates of the Tolbachik volcano, Kamchatka, Russia – Part 2: Tectosilicates Nadezhda V. Shchipalkina1, Igor V. Pekov1, Natalia N. Koshlyakova1, Sergey N. Britvin2,3, Natalia V. Zubkova1, Dmitry A. Varlamov4, and Eugeny G. Sidorov5 1Faculty of Geology, Moscow State University, Vorobievy Gory, 119991 Moscow, Russia 2Department of Crystallography, St Petersburg State University, University Embankment 7/9, 199034 St. Petersburg, Russia 3Kola Science Center of Russian Academy of Sciences, Fersman Str. 14, 184200 Apatity, Russia 4Institute of Experimental Mineralogy, Russian Academy of Sciences, Akademika Osypyana ul., 4, 142432 Chernogolovka, Russia 5Institute of Volcanology and Seismology, Far Eastern Branch of Russian Academy of Sciences, Piip Boulevard 9, 683006 Petropavlovsk-Kamchatsky, Russia Correspondence: Nadezhda V. Shchipalkina ([email protected]) Received: 19 June 2019 – Accepted: 1 November 2019 – Published: 29 January 2020 Abstract. This second of two companion articles devoted to silicate mineralization in fumaroles of the Tol- bachik volcano (Kamchatka, Russia) reports data on chemistry, crystal chemistry and occurrence of tectosil- icates: sanidine, anorthoclase, ferrisanidine, albite, anorthite, barium feldspar, leucite, nepheline, kalsilite, so- dalite and hauyne. Chemical and genetic features of fumarolic silicates are also summarized and discussed. These minerals are typically enriched with “ore” elements (As, Cu, Zn, Sn, Mo, W). Significant admixture of 5C As (up to 36 wt % As2O5 in sanidine) substituting Si is the most characteristic. Hauyne contains up to 4.2 wt % MoO3 and up to 1.7 wt % WO3.
    [Show full text]
  • A Geological Excursion to Port Cygnet in Connection with the Australasian Association for the Advancement of Science, 1902
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of Tasmania Open Access... A GEOLOGICAL EXCURSION TO PORT CYGNET IN CONNECTION WITH THE AUSTRALASIAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE, 1902. By W. H. Twelvetrees, F.G.S., Go vernmerd Geo log i.st [Read May 12. 1903.] The interest attaching to tlie plexus of felspathoid rocks, now known to occur at Port Cygnet, led to a flying visit being paid to the locality by members of Section C. (Geology) of the Anstralasian Association for the Advancement of Science, in January, 1902. The occurrence of this division of eruptive rocks in Tasmania is so restricted, and their development is exposed so instructively, that a brief account of the excursion will be interesting to others besides the actual visitors. Seventeen members took advantage of the opportunity, and travelled to Port Cygnet by one of the Channel steamers, making the trip in a few -hours. A call was made at Kettering, in the D'Entrecasteaux Channel, where Professor E. C. Hogg led the party to an exposure of Permo- Carboni- ferous till, with glaciated pebbles. Oyster Cove, where the belt of alkali rocks comes through from Port Cygnet, was not visited, the entire energies of the expedition being reserved for the better known area at Lovett. Elaeolite syenite, essexite and alkali rocks with trachytoidal ground- mass, occur at Oyster Cove. The assistance rendered to the cause of Science by the Hon. Edward Mulcahy, the then Minister of Lands, Works, and Mines, in lending the services of the two State geologists, was appreciated by the members and duly acknowledged at the time.
    [Show full text]
  • The Crystal Structure of Hauyne at 293 and 153 K
    Canadian Mineralogist Vol.29, pp. 123-130(1991) THE CRYSTALSTRUCTURE OF HAUYNEAT 293 AND 153 K ISHMAEL HASSAN{. ANDH. DOUGLAS GRUNDY Departmentof Geology,McMaster University, Hamilton, Ontario L8S4Ml ABSTRAcT dre de position dansle casdes atomes d'oxygdne du r6seau, du moins dansnotre echantillon, et nous ne voyons aucune The structure of hauyne, ideally Na6Ca2[Al6Si6O24] r€flexion satellitedans les clich6sde prdcession.Ces r6sul- (SOa)2,has beenrefined using separateintensity data-sets tats diffArent donc du cas de la nosdaneet de la lazurite' collected from the same single crystal at temperatures of danslesquels les atomc d'oxygbnedu r$eau occupentdeux 293 and 153 K, respectively.The refinementswere done ensemblesde positions 24(i), et la pr6sencede r6flexions in spacegroup P43n, and the final R indicesare 0.036and sate[itesd6coule d'une modulation dansla position desato- 0.039 for the 293 and 153 K data sets,respectively. The mes d'oxygbne. Al:Si ratio is l:1; theseatoms are completely ordered. There (Traduit par la R6daction) is positionaldisorder of the interstitialcations (Na, K, and Ca) over three independenr8(e) positions (sitesCl, C2, and Mots-clds:groupe de la sodalite,hauyne, structure cristal- C3) that are closeto eachother on the body diagonalsof line, mise en ordre de groupemants,bordures des domai- the cubic cell. The Cl, A, and C3 sitesare occupiedby nes antiphases. K, Ca, and Na, respectively.The sulfuratom of the SOI- group is displacedoff the 2(a)position to an 8(e)position, but the oxygenatoms have remainedat an 8(e) position, Ixtnooucrrou indicatingthat the SOagroup is in one orientationinstead of two.
    [Show full text]
  • Zeolites in Tasmania
    Mineral Resources Tasmania Tasmanian Geological Survey Record 1997/07 Tasmania Zeolites in Tasmania by R. S. Bottrill and J. L. Everard CONTENTS INTRODUCTION ……………………………………………………………………… 2 USES …………………………………………………………………………………… 2 ECONOMIC SIGNIFICANCE …………………………………………………………… 2 GEOLOGICAL OCCURRENCES ………………………………………………………… 2 TASMANIAN OCCURRENCES ………………………………………………………… 4 Devonian ………………………………………………………………………… 4 Permo-Triassic …………………………………………………………………… 4 Jurassic …………………………………………………………………………… 4 Cretaceous ………………………………………………………………………… 5 Tertiary …………………………………………………………………………… 5 EXPLORATION FOR ZEOLITES IN TASMANIA ………………………………………… 6 RESOURCE POTENTIAL ……………………………………………………………… 6 MINERAL OCCURRENCES …………………………………………………………… 7 Analcime (Analcite) NaAlSi2O6.H2O ……………………………………………… 7 Chabazite (Ca,Na2,K2)Al2Si4O12.6H2O …………………………………………… 7 Clinoptilolite (Ca,Na2,K2)2-3Al5Si13O36.12H2O ……………………………………… 7 Gismondine Ca2Al4Si4O16.9H2O …………………………………………………… 7 Gmelinite (Na2Ca)Al2Si4O12.6H2O7 ……………………………………………… 7 Gonnardite Na2CaAl5Si5O20.6H2O ………………………………………………… 10 Herschelite (Na,Ca,K)Al2Si4O12.6H2O……………………………………………… 10 Heulandite (Ca,Na2,K2)2-3Al5Si13O36.12H2O ……………………………………… 10 Laumontite CaAl2Si4O12.4H2O …………………………………………………… 10 Levyne (Ca2.5,Na)Al6Si12O36.6H2O ………………………………………………… 10 Mesolite Na2Ca2(Al6Si9O30).8H2O ………………………………………………… 10 Mordenite K2.8Na1.5Ca2(Al9Si39O96).29H2O ………………………………………… 10 Natrolite Na2(Al2Si3O10).2H2O …………………………………………………… 10 Phillipsite (Ca,Na,K)3Al3Si5O16.6H2O ……………………………………………… 11 Scolecite CaAl2Si3O10.3H20 ………………………………………………………
    [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]
  • On the Occurrence of a New Species of Garnet at Port Cygnet
    - ON THE OCCURRENCE OF A NEW SPECIES OF GARNET AT PORT CYGNET. By W. A. MACLEOD AND O. E. WHITE. THE Igneous rock containing this Garnet as a constant I The Specific gravity - accessOl"y constituent~ occurs as an outcrop about 6 feet Hardness ~ 7'5. Fusibility - 3'5 about. wide em the beach between Port Cygnet and Lymington. r, AnarY8is of m~sive Gt\rn~t from Brazil. It is intruded between other vole-olDie rocks, and, as far I TI. " )J Garnet, Port Cygnet. as could be ascertained from a hasty examination, 8eemB In. " " Trachyte " to be the only exposure in this locality_ From fossils [. II. 11[. SiO, 37'23 36'87 55'87 found it is pl'obably contemporaneous with the Permo­ AJ,O. 15'22 1'28 18'21 Carboniferous sediments. FeO 26'76 17'12 8'01 rrhe microscopical and chemical examinations of the MgO 3'1. 12'49 '46 rock point out its relationship to the Trachyte family. C.O 4'31 11'98 4'54 MnO 3'40 13'68 2'61 examples of which are so plentiful in this dietl-jet, and Na,O 3'36 which have been fully descrihed by Messrs. Twelve­ K,O 0'75 trees and Petterd.- Many of the varities of Trachyte 19nition loss 00'29 2'28 mentioned by them have melanite garnet as an accessory constituent. 99'71 101'09 The percentage of 8i O in this rock does not run very - 2 % Macroscopica.l chw'a.cuwistics -----o£ Garnet 'rrachyte. high for a Trachyt<l, being as low as 55'S7 ' Trachytes Bluish:.grey in colour on a fresh fractured surface, studded proper often include as much as 62%-64% of Silica.
    [Show full text]
  • Alphabetical List
    LIST L - MINERALS - ALPHABETICAL LIST Specific mineral Group name Specific mineral Group name acanthite sulfides asbolite oxides accessory minerals astrophyllite chain silicates actinolite clinoamphibole atacamite chlorides adamite arsenates augite clinopyroxene adularia alkali feldspar austinite arsenates aegirine clinopyroxene autunite phosphates aegirine-augite clinopyroxene awaruite alloys aenigmatite aenigmatite group axinite group sorosilicates aeschynite niobates azurite carbonates agate silica minerals babingtonite rhodonite group aikinite sulfides baddeleyite oxides akaganeite oxides barbosalite phosphates akermanite melilite group barite sulfates alabandite sulfides barium feldspar feldspar group alabaster barium silicates silicates albite plagioclase barylite sorosilicates alexandrite oxides bassanite sulfates allanite epidote group bastnaesite carbonates and fluorides alloclasite sulfides bavenite chain silicates allophane clay minerals bayerite oxides almandine garnet group beidellite clay minerals alpha quartz silica minerals beraunite phosphates alstonite carbonates berndtite sulfides altaite tellurides berryite sulfosalts alum sulfates berthierine serpentine group aluminum hydroxides oxides bertrandite sorosilicates aluminum oxides oxides beryl ring silicates alumohydrocalcite carbonates betafite niobates and tantalates alunite sulfates betekhtinite sulfides amazonite alkali feldspar beudantite arsenates and sulfates amber organic minerals bideauxite chlorides and fluorides amblygonite phosphates biotite mica group amethyst
    [Show full text]
  • (F, Cl, Br, and I) and S Ratios in Rock-Forming Minerals As
    minerals Article Changes in Halogen (F, Cl, Br, and I) and S Ratios in Rock-Forming Minerals as Monitors for Magmatic Differentiation, Volatile-Loss, and Hydrothermal Overprint: The Case for Peralkaline Systems Hans G.M. Eggenkamp 1,* , Michael A.W. Marks 1, Petya Atanasova 1,2, Thomas Wenzel 1 and Gregor Markl 1 1 Department of Geosciences, Eberhard-Karls-Universität Tübingen, Schnarrenbergstraße 94-96, D-72076 Tübingen, Germany; [email protected] (M.A.W.M.); [email protected] (P.A.); [email protected] (T.W.); [email protected] (G.M.) 2 Helmholtz-Zentrum Dresden—Rossendorf, Helmholtz Institute Freiberg for Resource Technology, 09599 Freiberg, Germany * Correspondence: [email protected] Received: 23 October 2020; Accepted: 5 November 2020; Published: 10 November 2020 Abstract: We determined the halogen (F, Cl, Br, and I) and sulfur (S) concentrations in Cl-rich rock-forming minerals from five peralkaline complexes. We investigated sodalite (N = 42), eudialyte-group minerals (N = 84), and tugtupite (N = 8) from representative rock samples derived from Ilímaussaq (South Greenland), Norra Kärr (Sweden), Tamazeght (Morocco), Lovozero, and Khibina (Russian Federation). Taken together, sodalite and eudialyte-group minerals dominate the Cl and Br budget of the investigated rocks. For F, however, several other phases (e.g., amphibole, fluorite, villiaumite, and minerals of the rinkite group and the apatite supergroup) are additional sinks, and parts of the S may be scavenged in generally rare sulfides. The investigated minerals contain Cl at the wt.% level, F and S concentrations are in the hundreds to thousands of µg/g-range, Br is less common (0.2–200 µg/g) and I is rare (mostly well below 1 µg/g).
    [Show full text]
  • Analysis of Mineral Trapping for CO2 Disposal in Deep Aquifers
    Analysis of Mineral Trapping for CO2 Disposal in Deep Aquifers Tianfu Xu, John A. Apps, and Karsten Pruess Earth Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720. Abstract. CO2 disposal into deep aquifers has been suggested as a potential means whereby atmospheric emissions of greenhouse gases may be reduced. However, our knowledge of the geohydrology, geochemistry, geophysics, and geomechanics of CO2 disposal must be refined if this technology is to be implemented safely, efficiently, and predictably. As a prelude to a fully coupled treatment of physical and chemical effects of CO2 injection, we have analyzed the impact of CO2 immobilization through carbonate precipitation. A survey of all major classes of rock-forming minerals, whose alteration would lead to carbonate precipitation, indicated that very few minerals are present in sufficient quantities in aquifer host rocks to permit significant sequestration of CO2. We performed batch reaction modeling of the geochemical evolution of three different aquifer mineralogies in the presence of CO2 at high pressure. Our modeling considered (1) redox processes that could be important in deep subsurface environments, (2) the presence of organic matter, (3) the kinetics of chemical interactions between the host rock minerals and the aqueous phase, and (4) CO2 solubility dependence on pressure, temperature and salinity of the system. The geochemical evolution under both natural background and CO2 injection conditions was evaluated. In addition, changes in porosity were monitored during the simulations. Results indicate that CO2 sequestration by matrix minerals varies considerably with rock type. Under favorable conditions the amount of CO2 that may be sequestered by precipitation of secondary carbonates is comparable with and can be larger than the effect of CO2 dissolution in pore waters.
    [Show full text]
  • INTRUSIVE IGNEOUS ROCKS, PART 3 (And Friends)
    GLY 4310C LAB 8 INTRUSIVE IGNEOUS ROCKS, PART 3 (and friends) Syenite, Phonolite, Ijolite, Carbonatite, Ultramafic Rocks and Lamprophyre These intrusive rocks correspond to fields 6, 6', 7, 7', 11, and 15 of figure 3-1 in Hyndman. The syenites are on the border between the QAP and the APF triangles. The remaining rocks are in the APF triangle. Phonolite is actually an extrusive or hypabyssal equivalent of nepheline syenite. The ultrmafic rocks and lamprophyre are very rich in mafic minerals. Consequently they cannot be plotted on the main part of the QAPF diagram, although technically they plot in field 16 (Figure 3-1, Hyndman) in a separate rectangle. More information on these rocks is available in Chapters 9, 14, 15, 16, and 17 in Moorhouse. SYENITE - Intrusive igneous, plutonic. The major mineral is feldspar, with greater than 65% alkali feldspar (K-spar or albite). The ferromagnesian minerals are usually # 20%. The K-spar is typically orthoclase, microcline or perthite. In dikes sanidine may be present. Any plagioclase present is generally subhedral and is often zoned (normal or oscillatory). Biotite is often present and is usually brown. Small amounts of feldspathoids, like nepheline and sodalite, may be present. If more than 5% of these minerals are present, the rock is called nepheline (or sodalite) syenite. Sphene, apatite, ilmenite, magnetite, zircon, and monzonite are accessories. In the IUGS classification, 0-5 Q, and P/(A+P) is 10-35. The name is for Syene (near Aswan), Egypt. Pliny the Elder named granite-like rocks from this area for the locality. ALKALI SYENITE - Intrusive igneous, plutonic.
    [Show full text]
  • Mineralogy of Southwest Montana by Michael J
    Mineralogy of Southwest Montana By Michael J. Gobla Covellite MBMG Museum Butte Presentation Outline • Montana Geologic Provinces • World Class Mineral Localities • Collecting in the Pioneer Mountains Gold, Highlands MBMG Museum Butte Gemstones • Two official State Gemstones • Montana Agate • Sapphire Corundum Rock Creek Montana Agate The Great Plains – Sedimentary Rocks Calcite, Barite, Gypsum, Montmorillonite, Quartz Calcite Montana Agate Carter County Yellowstone River Barite Cedar Creek Pertified Wood House Billings The Alkalic Province -Sediments Penetrated by Alkaline Intrusive Rocks • Aegirine, Augite, Biotite, Burbankite, Davanite, Eudialyte, Gold, Hauyne, Barytolamprophyllite, Nepheline, Olivine, Orthoclase, Phologopite, Sanadine, Wadeite Eudialyte Bearpaw Mts. The Absorka Province - Precambrian Metamorphics, Intrusive, and Volcanic Rocks Calcite Calcite, Chromite, Red Cliff Gallatin River Enstatite, Gold, Opal-Hyalite, Petrified Wood Platinum minerals Quartz replacing wood Wyoming Archean Province - Precambrian Metamorphic and Tertiary Intrusive Rocks • Metamorphic Rocks – Almandine, Anthophyllite, Corundum, Kyanite, Talc • Tertiary Intrusives – Gold • Pegmatites – Biotite, Schorl, Microcline, Dendritic Talc Muscovite, Rose Quartz Yellowstone Mine Corundum Elk Creek Mine The Rocky Mountains – Many Rock Types • Pegmatites – Quartz, Schorl, Microcline, Albite, Titanite, Epidote, Allanite • Skarns – Epidote, Magnetite, Scheelite, Grossular, Spinel • Tertiary Intrusives – Gold, Silver, Chalcocite, Galena, Diopside Hemimorphite, Pyrite,
    [Show full text]
  • Transmission Electron Microscopy Study of Optically Anisotropic and Isotropic Haiiyne
    American Mineralogist, Volume 80, pages 87-93, 1995 Transmission electron microscopy study of optically anisotropic and isotropic haiiyne HUIFANG Xu, * DAVID R. VEBLEN Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, Maryland 21218, U.S.A. ABSTRACT Optically anisotropic and isotropic haiiyne has been observed in phonolite from Niang- niang Hill, Jiangsu Province, southeastern China. Selected-area electron difITaction (SAED) and transmission electron microscopy (TEM) studies show the anisotropic haiiyne has a one-dimensional superstructure with a period of 6d1lO,ubalong one of the <110) directions of the ideal cubic haiiyne subcell. The superstructure may be considered as a periodic arrangement of (I 10) layer domains with P23 symmetry along [110]. Neighboring domains are related by a twin relationship. The unit-cell parameters for this haiiyne superstructure are thus metrically orthorhombic, with a,up = 2dilO'Ub,b,up = 6dllO,ub, c,uP = C,ub'but the most likely space group is monoclinic, Pn. SAED patterns and TEM images of two opti- cally isotropic haiiyne samples show they have either a three-dimensional superstructure or no superstructure. The average structure of the isotropic haiiyne with the superstructure is cubic, even though it is composed of twin domains with one-, two-, and three-dimen- sional superstructures. The superstructure may have formed by ordering of [Na3Ca(S04)]3+ and [(Na,KMOH)p+ clusters in the cubo-octahedral cages of the haiiyne framework during an arrested phase transition from P43n to P23 symmetry. INTRODUCI10N Taylor, 1967; Schultz, 1970; Morimoto, 1978; Tsuchiya Haiiyne, nosean, and lazurite are sodalite-group min- and Takeuchi, 1985).
    [Show full text]