DOCSLIB.ORG

Low-Temperature Heat-Capacities and Derived Thermodynamic Properties

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Low-Temperature Heat-Capacities and Derived Thermodynamic Properties Anerican Mineralogist, Volume 70, pages 249-260, I9B5 Low-temperature_heat-capacitiesand derivedthermodynamic properties of anthophyllite,diofside, enstatite,bronzite, and wollast'onitt Kn.nrern M. Knupr,ll D ep artment of Ge o scienc e s The Pennsylaania State Unioersity U niuersity P ark, Pennsyluania I 6802 RIcnc,RD A. Ronn, Bnucn S. HnMrNcw,qy U.S. Geological Suruey Reston, Virginia 22092 Dnnnrr,r, M. Knnnrcr D ep ar tment of Ge o scienc es The Pennsyloania State Uniuersity U niuersity P ark, P ennsyluania I 6802 ,c.NDJUN Iro2 The James Franck Institute The Uniuersity of Chicago Chicago, Illinois 6063 7 Abstract The heat capacitiesfor magnesio-anthophyllite,diopside, synthetic enstatite, bronzite, and wollastonite were measuredbetween 5 and 385 K by use of an adiabatic calorimeter.The entropy change si* - s3, in f(mol' K), is 538.9+2-7 for magnesio-anthophyllite [Mgu..Feo.rsiEo22(oH)2], 142.7+o.2 for diopside, 66.27+o.ro for synthetic ensiatite (MgSior), 69.04+0.10for bronzite(Mgo.rrFeo.rrSior), and 8r.69+0.r2 for wollastonite.The heat capacity, ci, for magnesio-anthophyllite,corrected to a composition of pure Mg- anthophyllite [Mgrsiroz(oH)r], resultsin a sles - sfi valueof 537.o*2.7/(mol.K). These resultsrepresent only the entropy calculatedfrom the measuredheat capacities.No configu- rational entropy wasadded. Although our Ci values for diopside and wollastonite differ significantly from those of previousstudies, especially at cryogenictemperatures, our entropiesat 298.15K are in close agreementwith the commonly acceptedvalues. Schottky heat capacity anomalieswere ob- servedbelow 25 K for magnesio-anthophyllite,diopside, and bronzite. The contribution of the magneticentropy arising from the interaction of Fe2+ with the ligand ficld of the crystals is discussed. Introduction (1932)also measuredthe Cfi of wollastonite over several, The previouslyaccepted entropies for diopsideand wol- often narrow, temp€ratureintervals between9 and 3(X K. lastonite at 298.15K were basedon a limited number of Prior to this study,low-temperature Ci data for magnesio- low-temperature Cfl measurements.King (1957) and anthophyllite and enstatitewere nonexistent,and heat ca- Wagner (1932)reported Ci valuesfor diopsidebetween 50 pacity measurementsby Kelley (1943)between 52 and 296 and 300 K and between20 and 40 K, respectively.Wagner K for a poorly characterizedsample of clinoenstatitewere usedto estimatethe thermodynamicproperties of enstatite. r Present address: GeosciencesResearch and Engineering De- Reliable valuesfor the entropiesof thesephases are criti- partrnent, Battelle, Pacific Northwest Laboratories, Richland, cally important to calculatingthe high-temperaturestabili- Washington99352. ty of these minerals and the metamorphic and igneous 2 Deceased. equilibriainvolving them. 0003-{04xl85/03O44249$02.W 249 250 KRUPKA ET AL.: LOW-TEMPERATURE HEAT CAPACITIES and Burn- Table 1. Chemical analyses of samples used in low-temperature hydrouspyribole structures(Veblen et al., 19'17; Veblen of heat capacity measurements ham, l978a,b).The magnesio-anthophyllitesample is composed at least95 percent(by volume)double chain material and approxi- Hotlastonited percent wider chains (Veblen, wdtten communication, flagnesio- - Diopsided -Enstatite.* Bronzite mately 5 anthophyllited (synthetlc)" (natural )c 1978).The distribution of disordered,wider chain material is not homogeneousin the sample. A description of the intergrowth 59.4 59.2n 55.86 51.8 Si 02 structuresin this anthophyllite samplewas given by Veblen and Ti 02 0.I 0.00 0.00 Buseck(1979). 0.00 <0.05 Al 203 0.95 0.20 CrZ03 0.1r 0.10 Diopside, CaMg(SiO) 2 0.05" Fe203 0.57 0.09 The white diopside samplewas collectedby one of us (DMK) (1970), Fe0 5.7 0,48 o.l2e 10.1 1e from an area near Zermztt, Switzerlandstudied by Bearth in the experimentalstudy of Slaughteret al' (1975)' fi90 30.2 18.0 40.80 3I.61 0.t2 and was used Examinationsby meansof X-ray diffraction and a petrogaphic Mn0 0.12 0.04 0,l9 0.00 microscopedid not reveal any impurities in the powdereddiop- Ni0 0.12 side.The chemicalcomposition given in Table I is in closeagree' Ca0 25,2 0.00 0.29 48.5 ment with the analysespresented by Slaughteret al. (1975)'The Na20 0.20 0.01 0.01 cell dimensionsgiven in Table 2 are in excellentagreernent with and Smith (1969)and in Kzo 0.07 0.02 0.0I the valuesfor diopsidepresentd by Borg the Joint Committeeof Powder Diffraction Standards(rcros) file Pzos 0.03 0,03 0.00 lI-654. coz 0,01 0.01 0.00 (0.01 H2o* 2.t 0.64 Bronzite, M g s.s5F es., 5SiOg Hzo- 0.22 0.08 The bronzite sample was describedby Huebner et al. (1979)' The calorimetricsample consisted of 3l pale-brown,single-crystal 1 : 100.52 100.I 0 100.20 98.82 100,49 Tota chips,that ranged in massfrom 0.19 to 1.65g. Optical examina- tion of each chip did not reveal any impurities.The composition aAnalyses completed by conbination of atomic absorption sPect'oscopy and of each chip was determined by electron-rnicroprobeanalysis stanlard wet-chemicaltechniques. See Shapi.o (1975) for a description of these analYtical techniques. using the method of Benceand Albee(1968). Multiple spot analy- DAveraqeof 84 spot probe analyses. gi,iiiqhiia-i"i-9i'ot'a totat oi 55 spot probe analvses fo.31 bronzite chips' sesof eachchip revealedno chemicalinhomogeneities within any dTotal iron as Fe20?. chemical composition for this eTotal iron as Feo,- single chip. A weighted-average sampleis givenin Table 1. Unit-cell dimensionswere measured for the most Mg- and Fe-rich bronzite chips, designatedK30 and K3l, respectively.The refinedcell constants(Table 2) are in good Minerals agreementwith those for bronzite as given in JCPDS patterns 19-605and 26-876. M agnesio -antho ph yllit e, M g6.sF e 6. 1 Si BO 2 z ( OH ) 2 gSiO The anthophyllite sample, designated'1.3.71.10, was collected by Synthetic enstotite, M 3 Prof. Peter Misch in the North Cascades at mile-marker 132.5 Enstatite crystals were prepared by growth from a lithium- along the North Cascades Highway (Washington Route 20) north vanadomolybdateflux using the method of Ito {1975).Residual of the eastern part of Lake Diablo. A small vein of light-green' flux was removedby solution with H2O in a sonic cleanerafter coarse-bladed anthophyllite was cut from the specimen, crushed, gentle crushing of the crystals. Further details are given by and sieved to the range of -35 to +100 mesh. Impurities were Kiupka (1984).Semi-quantitative emission spectroscopy analysis removed from the sample by using a Franz3 magnetic separator detected (maximal values): Li: 1100 ppm, Mo : 1200 ppm' : and heavyJiquid techniques. X-ray powder-diffraction methods Ni : 100 ppm, P : 910 ppm, V : 1500Ppm, and Zr l2O ppm' showed that the separated anthophyllite contained talc (<5%) as Microprobe results(Table 1) show that the syntheticenstatite is the only impurity. essentially pure, stoichiometric MgSiO3. Unit-cell dimensions The chemical analysis given in Table I is in close agreement weremeasured for two samplesof syntheticMgSiOr and are given with unpublished electron probe analyses provided by Prof. Misch in Table 2. Cell dimensionsof the calorimetricsample are in excel- and with other probe analyses completed during this study. Or- lent agreementwith those given by Ito (1975)for a similarly syn- thorhombic symmetry for the sample was confirmed by use of a thesizedenstatite. petrographic microscope. The unit-cell dimensions for the calori- given T,able 2, are in good agreement with the metric sample, in Wollastonite, CaSiOg values for synthetic, pure-Mg anthophyllite (Chernosky and sample from Willsboro, EssexCounty, New Autio, 1979) and for natural anthophyllite (Finger, 1970). The wollastonite Natural ScienceEstablishment' The anthophyllite sample was also tnalyznd for the presence of York, was purchasedfrom Wards The specimenwas crushed,sieved to the range of -35 to +100 mesh,and separatedby heavyJiquid techniques.X-ray diffraction and optical measurementson the final sampledid not reveal any 3 The use of trade namesis for descriptivepurposes only and impurities. Chemical analysesof the separatedwollastonite are doesnot imply endorsementby Battelle,Pacific Northwest Labo- given in Table 1. The refinedcell constants(Table 2) are in close ratories,U.S. GeologicSurvey, or The PennsylvaniaState Univer' agreementwith the valuesfor wollastonitegiven by Buergerand srty. Prewitt(1961). KRUPKA ET AL.: LOW-TEMPERATURE HEAT CAPACITIES 251 Table 2. Cell constantsfor samplesused in heat capacitymeasurements Magnesi o- Diopside -------Bronzite------ ------Enstatite------ tlol I astoni te anthophylI ite (natural) (synthetic) K30 K31 Ito-l lto-7 a (nm) 1.8536(3) 0.e749(1) 1.8250(3) 7.824e(2) r.8228(?l r.82re(2) 0.7e2s(1) b (nm) 1 TAAOr2\ 0.8925(I ) 0.8837(1) 0.8843(1) 0.8816(1) 0.8814(l) 0.7322(2) c (nn) o.5277(r) 0.52511(9) 0.5190(1) 0.51e3(l) 0.5180(1) 0.s178(1) 0.7069( r ) 90. 90' 90" 90" 90" 90. eo" 4'(2) B 90' rOso48.2,(e) 90' 90" 90' 90. 9s' 13.8'(e) 90' 90" 90' 90" 90' 90" 103"le'(l) v (nm3) 1.7606(4) 0.43966(8 ) 0.8370(2) 0.8380(2) 0.8325(2) 0.8316(2) 0.3e74(1) N 38 32 29 30 28 34 23 Note: Cell dimensionsgiven in nanometers(1 nm = l0 A). Numberin parenthesesis uncertainty in last digit. Cell dimensionswere measuredusing CuKcradiation. a N.ifilter, a scanning rate of 0.25o 20lmin, and BaFz (a = 0.61971t 0.0001 nm) as an internal standard. = N Numberof reflections used in'least-squares refinement program written by Applemanand Evans (1973). Apparatus and procedures [Mgu..Feo.rSi8O22(OH)2]by assumingthat 848.382g of Low-temperatureCi measurementswere made using the impure anthophyllite consist of I mole of magnesio- apparatusand techniquesdescribed by Robie and Heming- anthophyllite (802.900g) and 14.239g NaAlSi.O, glass, way (1972)and Robie et al.
Load more

Recommended publications
  • Download PDF About Minerals Sorted by Mineral Name
    MINERALS SORTED BY NAME Here is an alphabetical list of minerals discussed on this site. More information on and photographs of these minerals in Kentucky is available in the book “Rocks and Minerals of Kentucky” (Anderson, 1994). APATITE Crystal system: hexagonal. Fracture: conchoidal. Color: red, brown, white. Hardness: 5.0. Luster: opaque or semitransparent. Specific gravity: 3.1. Apatite, also called cellophane, occurs in peridotites in eastern and western Kentucky. A microcrystalline variety of collophane found in northern Woodford County is dark reddish brown, porous, and occurs in phosphatic beds, lenses, and nodules in the Tanglewood Member of the Lexington Limestone. Some fossils in the Tanglewood Member are coated with phosphate. Beds are generally very thin, but occasionally several feet thick. The Woodford County phosphate beds were mined during the early 1900s near Wallace, Ky. BARITE Crystal system: orthorhombic. Cleavage: often in groups of platy or tabular crystals. Color: usually white, but may be light shades of blue, brown, yellow, or red. Hardness: 3.0 to 3.5. Streak: white. Luster: vitreous to pearly. Specific gravity: 4.5. Tenacity: brittle. Uses: in heavy muds in oil-well drilling, to increase brilliance in the glass-making industry, as filler for paper, cosmetics, textiles, linoleum, rubber goods, paints. Barite generally occurs in a white massive variety (often appearing earthy when weathered), although some clear to bluish, bladed barite crystals have been observed in several vein deposits in central Kentucky, and commonly occurs as a solid solution series with celestite where barium and strontium can substitute for each other. Various nodular zones have been observed in Silurian–Devonian rocks in east-central Kentucky.
    [Show full text]
  • Wang Et Al., 2001
    American Mineralogist, Volume 86, pages 790–806, 2001 Characterization and comparison of structural and compositional features of planetary quadrilateral pyroxenes by Raman spectroscopy ALIAN WANG,* BRAD L. JOLLIFF, LARRY A. HASKIN, KARLA E. KUEBLER, AND KAREN M. VISKUPIC Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University, St. Louis, Missouri 63130, U.S.A. ABSTRACT This study reports the use of Raman spectral features to characterize the structural and composi- tional characteristics of different types of pyroxene from rocks as might be carried out using a por- table field spectrometer or by planetary on-surface exploration. Samples studied include lunar rocks, martian meteorites, and terrestrial rocks. The major structural types of quadrilateral pyroxene can be identified using their Raman spectral pattern and peak positions. Values of Mg/(Mg + Fe + Ca) of pyroxene in the (Mg, Fe, Ca) quadrilateral can be determined within an accuracy of ±0.1. The preci- sion for Ca/(Mg + Fe + Ca) values derived from Raman data is about the same, except that correc- tions must be made for very low-Ca and very high-Ca samples. Pyroxenes from basalts can be distinguished from those in plutonic equivalents from the distribution of their Mg′ [Mg/(Mg + Fe)] and Wo values, and this can be readily done using point-counting Raman measurements on unpre- pared rock samples. The correlation of Raman peak positions and spectral pattern provides criteria to distinguish pyroxenes with high proportions of non-quadrilateral components from (Mg, Fe, Ca) quadrilateral pyroxenes. INTRODUCTION pyroxene group of minerals is amenable to such identification Laser Raman spectroscopy is well suited for characteriza- and characterization.
    [Show full text]
  • Relict Forsterite in Unequilibrated Enstatite Chondrites N
    82nd Annual Meeting of The Meteoritical Society 2019 (LPI Contrib. No. 2157) 6322.pdf RELICT FORSTERITE IN UNEQUILIBRATED ENSTATITE CHONDRITES N. V. Almeida1, P. F Schofield1, K. Geraki2 and S. S. Russell1, 1Planetary Materials Group, Natural History Museum (London, SW7 5BD, U.K., [email protected]), 2Diamond Light Source Ltd. (Chilton, OX11 0DE, U.K.) Introduction: Enstatite chondrites are notable for their reduced mineralogy [1] and chemical similarity to the inner Solar System; indeed, they are considered isotopic twins of the Earth [2]. Solar and cosmogenic noble gas compositions also support heliocentric distances of EC parent bodies at 1-1.4 AU [e.g. 3]. While most authors have assumed that the ECs formed from material condensed at high C/O [e.g. 4], recent trace element work suggests that EC chondrule precursors may have formed in a more oxidising environment and were later reduced by exposure to a reducing Si- and S-rich gas [5]. This gas reduced the olivine to Mg-rich pyroxene and formed sulphides, thus EC chondrules record an evolving nebular composition from oxidising to reducing conditions. We have made a detailed study of relict olivine in primitive enstatite meteorites in order to test this model. Methods: Sections of Kota Kota (EH3; BM. 1905,105; P22810), MAC 88136 (EL3; 106) and Qingzhen (EH3; BM.1999,M27; P22813 & P22814) were studied. Element mapping by EDS (Zeiss EVO 15LS SEM) was used to locate olivine, followed by cathodoluminesece (CL) imaging and EPMA (Cameca SX100 microprobe) for mineral compositions. Synchrotron XRF maps and Ti-XANES data were acquired at beamline I18, Diamond Light Source.
    [Show full text]
  • Hydrothermal Alteration Experiments of Enstatite: Implications for Aqueous Alteration of Carbonaceous Chondrites
    Meteoritics & Planetary Science 42, Nr 1, 49–61 (2007) Abstract available online at http://meteoritics.org Hydrothermal alteration experiments of enstatite: Implications for aqueous alteration of carbonaceous chondrites Ichiro OHNISHI1* and Kazushige TOMEOKA1, 2 1Graduate School of Science and Technology, Kobe University, Kobe 657-8501, Japan 2Department of Earth and Planetary Sciences, Faculty of Science, Kobe University, Kobe 657-8501, Japan *Corresponding author. E-mail: [email protected] (Received 28 March 2006; revision accepted 04 November 2006) Abstract–Enstatite is one of the major constituent minerals in carbonaceous chondrites. Hydrothermal alteration experiments (26 in total) of enstatite were carried out at pH 0, 6, 7, 12, 13, and 14, at temperatures of 100, 200, and 300 °C, and for run durations of 24, 72, 168, and 336 h in order to provide constraints on the aqueous-alteration conditions of the meteorites. The recovered samples were studied in detail by using powder X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Under acidic and mildly acidic conditions (pH 0, 6), no significant alteration occurred, whereas under neutral to alkaline conditions (pH 7–14), serpentine and saponite formed in various proportions by replacing enstatite. At 300 °C for 168 h, serpentine formed under neutral to moderately alkaline conditions (pH 7, 12), and serpentine and saponite formed as unit cell-scale coherent intergrowths under highly alkaline conditions (pH 13, 14). The amounts of phyllosilicates have a tendency to increase with increasing pH, temperature, and run duration. There is also a tendency for saponite to form at higher pH and temperature and under longer run-durations than serpentine.
    [Show full text]
  • Petrography and Engineering Properties of Igneous Rocks
    ENGINEERil~G MONOGRAPHS No. I United States Department of the Interior BUREAU OF RECLAMATION PETROGRAPIIY AND ENGINEERING· PROPER11ES OF IGNEOUS ROCKS hy Rit~bard C. 1\lielenz Denver, Colorado October 1948 95 cents (R.evised September 1961) United States Department of the Interior STEWART L. UDALL, Secretacy Bureau of Reclamation FLOYD E. DOMINY, Commissioner G~T BLOODGOOD, Assistant Commissioner and Chief Engineer Engineering Monograph No. 1 PETROGRAPHY AND ENGINEERING PROPERTIRES ·OF IGNEOUS RO<;:KS by Richard C. Mielenz Revised 1959. by William Y. Holland Head. Petrographic Laboratory Section Chemical Engineering Laboratory Branch Commissioner's Office. Denver Technical Infortnation Branch Denver Federal Center Denver, Colorado ENGINEERING MONOGRAPHS are published in limited editions for the technical staff of the Bureau of Reclamation and interested technical circles in Government and private agencies. Their purpose is to record devel­ opments, innovations, .and progress in the engineering and scientific techniques and practices that are employed in the planning, design, construction, and operation of Rec­ lamation structures and equipment. Copies 'may be obtained from the Bureau of Recla- · mation, Denver Federal Center, Denver, Colon.do, and Washington, D. C. Excavation and concreting of altered zones in rhyolite dike in the spillway foundation. Davis Damsite. Arizona-Nevada. Fl'ontispiece CONTENTS Page Introduction . 1 General Basis of Classification of Rocks . 1 Relation of the Petrographic Character to the Engineering Properties of Rocks . 3 Engineering J?roperties of Igneous Rocks ................................ :. 4 Plutonic Rocks . 4 Hypabyssal Rocks . 6 Volcanic Rocks..... 7 Application of Petrography to Engineering Problems of the Bureau of Reclamation . 8 A Mineralogic and Textural Classification of Igneous Rocks .
    [Show full text]
  • Thermal Metamorphism in Enstatite Chondrites As Fundamental
    49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083) 1016.pdf THERMAL METAMORPHISM IN ENSTATITE CHONDRITES AS A FUNDAMENTAL PROCESS IN THE EVOLUTION OF PLANETARY BODIES: INFORMATION FROM ELEMENTAL DISTRIBUTIONS IN THE MINERAL FRACTIONS. Z.A. Lavrentjeva, Lyul A.Yu. V. I. Vernadsky Institute of Geochemistry and Analytical Chemistry, RAS, Moscow, E-mail: [email protected] Introduction. Enstatite chondrites (ECS) are metamorphism [18]. An understanding of metamorphic thought to have formed in highly reducing environ- reactions is useful because it offers insight into parent ment. This inference is supported by the high body processes and means of identifying the most Mg/(Mg+Fe) of olivine and pyroxene, presence of Si primitive chondrites [17]. Extrapolation of the reac- in Fe,Ni-metal, and occurrence of typically lithophile tions that occur during incipient metamorphism in or- elements, such as Ca, Mg, Mn and K, in sulfide miner- dinary and carbonaceous chondrites [2] to enstatite als in enstatite chondrites [1]. ECS are divided into two chondrites is plausible [6], yet different reactions may main groups, EH and EL, based on high and low abun- be significant in light of the distinct mineralogy (and dances of Fe,Ni metal: both groups show a metamor- hence formation conditions) of enstatite chondrites. phic sequence from type 3 to 6, similar to that ob- Both groups EH and EL enstatite chondrites show a served in ordinary chondrites [2]. Enstatite chondrites metamorphic sequence from type 3 to 6 similar to that are well known to be the most reduced chondrites. observed in ordinary chondrites. In contrast, although a However, primitive ECS contain minor FeO-rich (>3 general sense for metamorphic grade in enstatite chon- wt% FeO) silicates which obviously formed under drites has been determined [3-6], a detailed under- more oxidizing conditions than the bulk of the EC ma- standing of metamorphic petrogenesis remains elusive.
    [Show full text]
  • Minerals Found in Michigan Listed by County
    Michigan Minerals Listed by Mineral Name Based on MI DEQ GSD Bulletin 6 “Mineralogy of Michigan” Actinolite, Dickinson, Gogebic, Gratiot, and Anthonyite, Houghton County Marquette counties Anthophyllite, Dickinson, and Marquette counties Aegirinaugite, Marquette County Antigorite, Dickinson, and Marquette counties Aegirine, Marquette County Apatite, Baraga, Dickinson, Houghton, Iron, Albite, Dickinson, Gratiot, Houghton, Keweenaw, Kalkaska, Keweenaw, Marquette, and Monroe and Marquette counties counties Algodonite, Baraga, Houghton, Keweenaw, and Aphrosiderite, Gogebic, Iron, and Marquette Ontonagon counties counties Allanite, Gogebic, Iron, and Marquette counties Apophyllite, Houghton, and Keweenaw counties Almandite, Dickinson, Keweenaw, and Marquette Aragonite, Gogebic, Iron, Jackson, Marquette, and counties Monroe counties Alunite, Iron County Arsenopyrite, Marquette, and Menominee counties Analcite, Houghton, Keweenaw, and Ontonagon counties Atacamite, Houghton, Keweenaw, and Ontonagon counties Anatase, Gratiot, Houghton, Keweenaw, Marquette, and Ontonagon counties Augite, Dickinson, Genesee, Gratiot, Houghton, Iron, Keweenaw, Marquette, and Ontonagon counties Andalusite, Iron, and Marquette counties Awarurite, Marquette County Andesine, Keweenaw County Axinite, Gogebic, and Marquette counties Andradite, Dickinson County Azurite, Dickinson, Keweenaw, Marquette, and Anglesite, Marquette County Ontonagon counties Anhydrite, Bay, Berrien, Gratiot, Houghton, Babingtonite, Keweenaw County Isabella, Kalamazoo, Kent, Keweenaw, Macomb, Manistee,
    [Show full text]
  • Diopside, Enstatite and Forsterite Solubilities in H2O and H2O-Nacl Solutions at Lower Crustal and Upper Mantle Conditions
    Journal Pre-proofs Diopside, enstatite and forsterite solubilities in H2O and H2O-NaCl solutions at lower crustal and upper mantle conditions Catherine A. Macris, Robert C. Newton, Jeremy Wykes, Ruiguang Pan, Craig E. Manning PII: S0016-7037(20)30206-4 DOI: https://doi.org/10.1016/j.gca.2020.03.035 Reference: GCA 11712 To appear in: Geochimica et Cosmochimica Acta Received Date: 16 December 2019 Revised Date: 17 March 2020 Accepted Date: 24 March 2020 Please cite this article as: Macris, C.A., Newton, R.C., Wykes, J., Pan, R., Manning, C.E., Diopside, enstatite and forsterite solubilities in H2O and H2O-NaCl solutions at lower crustal and upper mantle conditions, Geochimica et Cosmochimica Acta (2020), doi: https://doi.org/10.1016/j.gca.2020.03.035 This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Elsevier Ltd. All rights reserved. Diopside, enstatite and forsterite solubilities in H2O and H2O-NaCl solutions at lower crustal and upper mantle conditions Catherine A. Macris1,2, Robert C. Newton1, Jeremy Wykes3, Ruiguang Pan2 and Craig E.
    [Show full text]
  • 1 Chemical Effects of Metamorphism on Enstatite
    Chemical Effects of Metamorphism on Enstatite Chondrites Nicholas Emm April 28, 2020 GEOL394 – Senior Thesis II: Research Advisor: Dr. Richard Ash 1 Abstract Chondrites are the most primitive and most unaltered form for any group of meteorites. The relative abundance of rock forming elements that are found in chondrites are similar to those of the Sun. Chondrites make up about 90% of all meteorite falls, so this group of meteorites are relatively common. I will be investigating the process of metamorphism in a specific subgroup of chondrites called enstatite chondrites. Enstatite chondrites make up only 2% of all meteorites that fall to the Earth and they are unique in their reduced mineralogy and their isotopic similarity to the Earth. Enstatite chondrites are assigned a metamorphic grade based on textural properties. Currently, there is no reliable quantitative method to determine the metamorphic grade for enstatite chondrites. Therefore, the overarching goal of this project is to build a more reliable, quantitative method to determine the metamorphic grade of enstatite chondrites. To do this, trace element concentrations will be measured, and this will be supported by a calculation of relative standard deviation (RSD) to estimate their variation. Major elements cannot be used because enstatite chondrites are rich in magnesium, so comparisons between major elements becomes difficult when there is one dominant major element. Typically, as meteorites are metamorphosed, elements diffuse and trend toward equilibration (homogenize). Therefore, as the grade of metamorphism increases, the expectation is that trace elements will homogenize for all enstatite grains. By utilizing petrography and the Electron Probe Microanalyzer (EPMA) to locate enstatite grains, trace elements present in enstatite chondrites were measured by way of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS).
    [Show full text]
  • Polysynthetically-Twinned Structures of Enstatite and Wollastonite
    Phys Chem Minerals (1984) 10:217-229 PHYSICS CHEMISTRY [[MIHERALS © Springer-Verlag 1984 Polysynthetically-Twinned Structures of Enstatite and Wollastonite Yoshikazu Ohashi * Department of Geology, University of Pennsylvania, Philadelphia, PA 19104, USA Abstract. Crystal structures of clinoenstatite, orthoenstatite, wollastonite polytypes established the structural relation- wollastonite-lT and wollastonite-2M (parawollastonite) ships between polytypes (Morimoto et al. 1960; Burnham were refined to an R factor 3-4 percent level. Molar vol- 1967; Morimoto and Koto 1969; Trojer 1968), and empha- umes at room temperature are 31.270(15), 31.315(8), sized the close relationship of the structure to the model 39.842(5) and 39.901(10) cm3/MSiO3, in the above-men- produced by applying mathematical operations to the basic tioned order, indicating that one-layer polytypes (clinoen- slab. Stacking sequences of new 3T, 4T, 5T, and 7T wollas- statite and wollastonite-lT) are stable at higher pressures tonite polytypes were determined (Henmi etal. 1978; than two-layer polytypes (orthoenstatite and wollastonite- Henmi et al. 1983), although refinements of atomic coordi- 2M). The polytypic relation of the enstatite polytypes can nates of these longer repeat polytypes were impossible. be described by four twinning operations - b glide [1 to Because of the similarities in chemistries and silicate (110), a glide I[ to (001), twofold screw axis [I to a (of linkages, and the existence of polytypes, enstatite and wol- orthoenstatite) and a twofold screw axis I[ to c. For the lastonite are often compared in parallel. Polytypes of ensta- wollastonite polytypes, twinning operations are twofold tite and wollastonite are, however, different in the way twin- screw axis II to b and a glide [I to (010).
    [Show full text]
  • Second International Kimberlite Conference: Extended Abstracts
    226 ENSTATITE XENOCRYST CONTAINING COEXISTING Cr-POOR AND Cr-RICH GARNET, WELTEVREDEN FLOORS, SOUTH AFRICA. Henry O.A. Meyer: Dept, of Geosciences, Purdue University, Hsiao-ming Tsai: West Lafayette, Ind. 47907 John J. Gurney: Dept, of Geochemistry, University of Cape Town, Rondebosch, South Africa The genesis and depth of origin of the large xenocrysts of garnet, ilmenite, diopside and enstatite that occur in kimberlite is still a major problem with respect to petrologic models of the upper mantle. The relation of these xenocrysts to other kimberlitic minerals and the constituents of the ultramafic xenoliths is unknown. Of particular interest in this context was the discovery of a large (~20 cm) single crystal of enstatite (Enss) containing abundant Mg-ilmenite (Mg0~12 wt.%) and rarer polyphase garnet inclusions. This xenocryst was obtained from Weltevreden Floors near the pre¬ sent Frank Smith Mine, South Africa. The polyphase garnet inclusions are unique in that they consist of two chemically distinct suites of minerals - one Cr-rich and one Cr-poor. The major garnet phase is orange in color and is predominantly pyrope-almandine (Py7iAI2iGre) (Table 1,4) whereas inside this garnet is a second one that is pink and Cr-rich (CrPy33Py2sAl1gGrz0) (Table, 5). This inner chrome-pyrope garnet itself contains Cr-diopside, (Table 1,6) chromite (Table 1,9) and ilmenite. The enclosing orange almandine-pyrope contains rounded Mg-ilmenites (Table 1,3) at the boundary with the Cr-pyrope as well as elongated strings of both olivine (Foee) (Table 1,8) and another diopside (Table 1,7). The assemblage described above is shown diagrammatically in fig.
    [Show full text]
  • Download PDF About Minerals Sorted by Mineral Group
    MINERALS SORTED BY MINERAL GROUP Most minerals are chemically classified as native elements, sulfides, sulfates, oxides, silicates, carbonates, phosphates, halides, nitrates, tungstates, molybdates, arsenates, or vanadates. More information on and photographs of these minerals in Kentucky is available in the book “Rocks and Minerals of Kentucky” (Anderson, 1994). NATIVE ELEMENTS (DIAMOND, SULFUR, GOLD) Native elements are minerals composed of only one element, such as copper, sulfur, gold, silver, and diamond. They are not common in Kentucky, but are mentioned because of their appeal to collectors. DIAMOND Crystal system: isometric. Cleavage: perfect octahedral. Color: colorless, pale shades of yellow, orange, or blue. Hardness: 10. Specific gravity: 3.5. Uses: jewelry, saws, polishing equipment. Diamond, the hardest of any naturally formed mineral, is also highly refractive, causing light to be split into a spectrum of colors commonly called play of colors. Because of its high specific gravity, it is easily concentrated in alluvial gravels, where it can be mined. This is one of the main mining methods used in South Africa, where most of the world's diamonds originate. The source rock of diamonds is the igneous rock kimberlite, also referred to as diamond pipe. A nongem variety of diamond is called bort. Kentucky has kimberlites in Elliott County in eastern Kentucky and Crittenden and Livingston Counties in western Kentucky, but no diamonds have ever been discovered in or authenticated from these rocks. A diamond was found in Adair County, but it was determined to have been brought in from somewhere else. SULFUR Crystal system: orthorhombic. Fracture: uneven. Color: yellow. Hardness 1 to 2.
    [Show full text]