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CHEMISTRY (606 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 13)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 42)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 21)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 23)
ACS Macro Letters     Full-text available via subscription   (Followers: 27)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 42)
ACS Nano     Full-text available via subscription   (Followers: 271)
ACS Photonics     Full-text available via subscription   (Followers: 12)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 23)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chimica Slovenica     Open Access  
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 6)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 51)
Advanced Science Focus     Free   (Followers: 4)
Advances in Chemical Engineering and Science     Open Access   (Followers: 64)
Advances in Chemical Science     Open Access   (Followers: 15)
Advances in Chemistry     Open Access   (Followers: 20)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18)
Advances in Drug Research     Full-text available via subscription   (Followers: 24)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 24)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 16)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 3)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 68)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Chemistry     Open Access   (Followers: 30)
American Journal of Plant Physiology     Open Access   (Followers: 14)
American Mineralogist     Hybrid Journal   (Followers: 15)
Analyst     Full-text available via subscription   (Followers: 40)
Angewandte Chemie     Hybrid Journal   (Followers: 175)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 238)
Annales UMCS, Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 5)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 28)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access   (Followers: 1)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 343)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 20)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 125)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 86)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 70)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 8)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 9)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 17)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 72)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 25)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 22)
Chemical Reviews     Full-text available via subscription   (Followers: 194)
Chemical Science     Open Access   (Followers: 24)
Chemical Technology     Open Access   (Followers: 20)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 8)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Hybrid Journal   (Followers: 5)
Chemistry - A European Journal     Hybrid Journal   (Followers: 163)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Materials     Full-text available via subscription   (Followers: 251)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 22)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 11)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 11)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography     Open Access   (Followers: 2)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 2)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal  
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 18)
Current Research in Chemistry     Open Access   (Followers: 9)
Current Science     Open Access   (Followers: 65)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  
Drying Technology: An International Journal     Hybrid Journal   (Followers: 4)
Eclética Química     Open Access   (Followers: 1)

        1 2 3 4 | Last

Journal Cover American Mineralogist
  [SJR: 1.185]   [H-I: 104]   [15 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0003-004X
   Published by GeoScienceWorld Homepage  [15 journals]
  • Rutile: A novel recorder of high-fO2 fluids in subduction zones
    • Authors: Cruz-Uribe A. M.
      Pages: 2153 - 2153
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6261
      Issue No: Vol. 102, No. 11 (2017)
  • Granites and rhyolites: Messages from Hong Kong, courtesy of zircon
    • Authors: Miller C. F.
      Pages: 2154 - 2156
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6260
      Issue No: Vol. 102, No. 11 (2017)
  • Do Fe-Ti-oxide magmas exist' Probably not!
    • Authors: Lindsley, D. H; Epler, N.
      Pages: 2157 - 2169
      Abstract: Many Fe-Ti oxide bodies associated with anorthosite suites and with some tholeiitic plutonic bodies have cross-cutting relationships with their host rocks suggesting that they may have been emplaced as oxide melts. Pure Fe-Ti oxides melt at temperatures much higher than is considered to be geologically realistic, so various fluxes (mainly apatite, fluorine, or carbon) have been called upon to stabilize the melts down to plausible temperatures. This review traces our experimental attempts to test the effectiveness of proposed fluxes and therefore to demonstrate the existence of such melts at geologically realistic temperatures.Neither F-apatite nor carbon act to stabilize Ti-rich Fe-Ti oxide melts at 1300 °C and below, and we conclude that—unless some totally unforeseen material does serve as a flux—Fe-Ti oxide magmas almost certainly do not exist. Although our data are not conclusive, it appears that increasing contents of FeO (and possibly TiO2) and P2O5 mutually enhance their solubilities in silicate melts, allowing extensive buildup of those components in melts residual to anorthosite. We interpret that oxide orebodies form by gravitational accumulation of crystalline oxides from such liquids. Once those melts become saturated with either Fe-Ti oxides or apatite, both phases will tend to co-precipitate, thus explaining the common occurrence of apatite with oxide orebodies ("nelsonites"). Cross-cutting oxide bodies were probably emplaced as crystalline oxides, possibly lubricated by small amounts of residual silicate liquid. Oxidation of the Fe2TiO4 component in initially ulvospinel-rich spinel and concomitant formation of ilmenite grains by granule-oxy-"exsolution" may have weakened the crystalline oxide and facilitated its flow during emplacement.It seems clear, though, that the presence of carbon does stabilize Ti-poor iron oxide melts to very low temperatures (at and even below 1000 °C), consistent with the (disputed!) magmatic origin of the magnetite lavas at El Laco, Chile.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6091
      Issue No: Vol. 102, No. 11 (2017)
  • Calcium (Ti,Zr) hexaorthophosphate bioceramics for electrically stimulated
           biomedical implant devices: A position paper
    • Authors: Heimann R. B.
      Pages: 2170 - 2179
      Abstract: Osseointegration of biomedical implants as well as healing of broken bones are supported by novel bioceramic materials that, owing to their engineered ionic conductivity, in the presence of an electric field provide accumulation of negative electrical charges close to the interface between an implant and living bone tissue, thus stimulating the rate of bone growth. In this position paper, the structure as well as the chemical, electrical, and biomedical properties of Ca (Ti,Zr) hexaorthophosphates are reviewed. In addition, based on evaluation of the material’s properties, a conceptual configuration of a capacity-coupled bone growth stimulator will be presented. The advantage of the proposed novel device over already existing bone-growth stimulators is its provision of the intimate contact of a capacity-coupled electric field with the growing bone tissue as opposed to an externally applied inductively coupled electromagnetic field, which suffers substantial attenuation when transmitted through soft tissue covering the locus of bone growth. To achieve higher ionic conductivity in Ca (Ti,Zr) hexaorthophosphates, aliovalent doping with highly mobile Na or Li ions intercalated into the only partially occupied M1 sites appears to be a suitable route.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6165
      Issue No: Vol. 102, No. 11 (2017)
  • Raman spectroscopy of water-rich stishovite and dense high-pressure silica
           up to 55 GPa
    • Authors: Nisr, C; Shim, S.-H, Leinenweber, K, Chizmeshya, A.
      Pages: 2180 - 2189
      Abstract: Recent studies have shown that mineral end-member phases (-AlOOH phase, phase H, and stishovite) with rutile-type or modified rutile-type crystal structures and solid solutions between them in the MgO-Al2O3-SiO2 system can store large amounts of water and can be stable at high pressures and high temperatures relevant to the Earth’s lower mantle. The Al-H charge-coupled substitution (Si4+ -> Al3+ + H+) has been proposed to explain the storage capacity found in some of these phases. However, the amount of H+ found in some recent examples does not match the expected value if such substitution is dominant, and it is difficult to explain the larger water storage in stishovite with such a mechanism alone. An octahedral version of the hydrogarnet-like substitution (Si4+ -> 4H+) has been proposed to explain the incorporation of protons in Al-free, water-rich stishovite. Yet, the high-pressure structural behavior of OH in this phase has not yet been measured. In this study, we report high-pressure Raman spectroscopy measurements on Al-free hydrous stishovite with 3.2 ± 0.5 wt% water up to 55 GPa. At ambient pressure, we find that the OH stretching modes in this phase have frequencies lying in between those in low-water aluminous stishovite and those in -AlOOH, suggesting a strength of the hydrogen bonding intermediate between these two cases. After decompression to 1 bar, we observe modes that are similar to the IR-active modes of anhydrous and hydrous stishovite, suggesting that the existence of Si defects in the crystal structure can activate the inactive modes. For both lattice and OH-stretching modes, our data show a series of changes at pressures between 24 and 28 GPa suggesting a phase transition (likely to CaCl2-type). While some of the lattice mode behaviors are similar to what was predicted for the AlOOH polymorphs, the OH mode of our hydrous stishovite shows a positive frequency shift with pressure, which is different from -AlOOH. All our spectral observations suggest that water-rich pure dense silica has a distinct proton incorporation mechanism from aluminous low-water stishovite and -AlOOH, supporting the proposed direct substitution.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-5944
      Issue No: Vol. 102, No. 11 (2017)
  • Tracking the evolution of Late Mesozoic arc-related magmatic systems in
           Hong Kong using in-situ U-Pb dating and trace element analyses in zircon
    • Authors: Tang, D. L. K; Wilson, C. J. N, Sewell, R. J, Seward, D, Chan, L. S, Ireland, T. R, Wooden, J. L.
      Pages: 2190 - 2219
      Abstract: The links between large-scale silicic volcanism and plutonism offer insights into the dynamics of crustal magmatic systems and growth of continental crust. In Hong Kong, voluminous silicic ignimbrites and linked plutons record a ~26 Myr period of magmatism from ~164 to 138 Ma. We present data from these linked volcanic-plutonic assemblages at the Lantau and High Island caldera complexes, with an emphasis on the ~143–138 Ma activity from the latter. To track the evolution of these magmatic systems, U-Pb dating and trace element analyses using secondary-ion mass spectrometry (SIMS) were carried out on zircons from 21 samples from both volcanic and plutonic samples. The SIMS age data sets divide into two groups across volcanic and plutonic origins: (1) seven samples with unimodal age spectra [five of which have the same mean value as the published Isotope Dilution Thermal Ionization Mass Spectrometry (ID-TIMS) age from the same sample]; and (2) 14 samples yielding multiple age components. Age patterns from both groups suggest that the previously separated ~143 Ma Repulse Bay (RBVG) and ~141–140 Ma Kau Sai Chau volcanic groups (KSCVG) instead represent activities over a single ~5 Myr period. Direct linkages previously proposed between some volcanic and plutonic units for this period (e.g., High Island Tuff, Kowloon Granite) are no longer supported, and magmatism represented by exposed plutons continued until 137.8 ± 0.8 Ma (Mount Butler Granite). Under CL imagery, a wide range of zircon textures identified in both volcanic and plutonic samples is indicative of complex processes, some of which are identified through trace element data coupled with textural characteristics. Overall, intra-grain (cores vs. rims; sector-zonation) and intra-sample variations in trace element abundances and ratios are larger than those between samples. Zircon chemistries in both volcanic and plutonic samples fall into two groups during the ~5 Myr history of the High Island caldera magmatic system. One group (RBVG and "cold" granites) includes inherited grains back to 164 Ma and wider ranges in Hf, Y, total trivalent elements, Th and U concentrations and Th/U, Yb/Gd, and U/Yb ratios than the other (KSCVG and "hot" granites). Two possible evolutionary models of the High Island caldera magmatic system are: (1) the system randomly tapped a single crustal domain that fluctuated in temperature as a result of varying interactions of hotter melts, or (2) the volcanic and plutonic records reflect the interplay of two crustal domains with contrasting "low-" and "high-temperature" characteristics. In Hong Kong, some plutonic bodies were comagmatic with large-scale volcanism, while others were emplaced at shallow crustal levels independently of volcanism, matching the current two end-member views of the volcanic-plutonic relationship.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6071
      Issue No: Vol. 102, No. 11 (2017)
  • Defect contributions to the heat capacities and stabilities of some chain,
           ring, and sheet silicates, with implications for mantle minerals
    • Authors: Nesbitt, H. W; Cormack, A. N, Henderson, G. S.
      Pages: 2220 - 2229
      Abstract: At temperatures less than ~1500 K, previously published CP data demonstrate that the heat capacities of orthoenstatite, proto-enstatite, diopside, and pseudowollastonite include primarily Debye type vibrational and anharmonic contributions, whereas the alkali chain, sheet, and ring silicates, Na2SiO3, Li2SiO3, K2SiO3, and Na2Si2O5 include a third contribution. The third contribution to CP arises from defect formation due to the mobility Na, K, Li, and O2–. The contribution becomes apparent at temperatures above 700–800 K for Na and K silicates, and above 900–1000 K for Li metasilicate. With strong thermal agitation, alkali-non-bridging oxygen (NBO) bonds are ruptured with the cations exiting their structural sites to occupy interstitial sites, thereby producing intrinsic Frenkel defects, which contribute to the CP of the alkali silicates. The magnitudes of the CP defect contributions correlate inversely with cation-oxygen bond strengths, as measured by bond dissociation energies. K-O and Na-O bond strengths are weak (239 and 257 kJ/mol) and defect contributions are large for these alkali chain, ring, and sheet silicates. The greater bond strength of Li-O (341 kJ/mol) correlates with a weaker defect contribution to the CP of Li2SiO3. Mg-O and Ca-O bonds are stronger still (394 and 464 kJ/mol) and no CP defect contributions are observed for the pyroxenes and pseudowollastonite up to ~1500 K.Above ~800 K a polymerization reaction occurs in Na2SiO3, which produces some Q3 species and free oxygen (O2– or oxide ion). The polymerization reaction annihilates an oxygen structural site so that the O2– produced must reside on non-structural sites thus producing intrinsic anionic defects. The same reactions likely occur in Na2Si2O5 and K2SiO3. Raman spectra of Na2SiO3 indicate>10% of Na+ and ~1.7% of O2– on interstitial sites at 1348 K.Ca- and Mg-bearing mantle minerals subjected to temperature greater than ~1500 K experience the destabilizing effects of disordering (Frenkel defect formation). The minerals may respond either by changing their composition or by changing phase. An abundance of Ca and Na defects in pyroxenes, for example, likely promotes production of new components (e.g., CaAl2SiO6, NaAlSi2O6) in pyroxenes. By their production, Ca and Na defect concentrations are reduced thereby stabilizing the phases. Mg-O bond dissociation and production of intrinsic Mg2+ and O2– point defects within olivine likely destabilize it and promote the phase transition to wadsleyite at the base of the upper mantle.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6103
      Issue No: Vol. 102, No. 11 (2017)
  • Phase transition in SiC from zinc-blende to rock-salt structure and
           implications for carbon-rich extrasolar planets
    • Authors: Kidokoro, Y; Umemoto, K, Hirose, K, Ohishi, Y.
      Pages: 2230 - 2234
      Abstract: We have investigated the phase transition in SiC between the zinc-blende and rock-salt structures at high pressure and temperature in a laser-heated diamond-anvil cell. Results demonstrate that the transition occurs at 74 GPa and 2100 K with a 21% density increase, reflecting the coordination number rising from four to six. In addition, our ab initio calculations show that the boundary has a negative Clapeyron slope of –4.0 MPa/K at 2000 K. The experimentally determined phase boundary is located between those predicted by GGA and B3LYP functional. This transition may take place inside carbon-rich extrasolar planets, forming a boundary with a large density jump. Since SiC is rigid and highly thermally conductive, thermal convection in an SiC-dominant layer is not likely to occur. Nevertheless, the convection may be possible if planet interiors include both silicon carbide and silicate, and in this case the phase transition could affect the style of thermal convection.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6033
      Issue No: Vol. 102, No. 11 (2017)
  • Non-destructive, multi-method, internal analysis of multiple inclusions in
           a single diamond: First occurrence of mackinawite (Fe,Ni)1+xS
    • Authors: Agrosi, G; Tempesta, G, Mele, D, Allegretta, I, Terzano, R, Shirey, S. B, Pearson, G. D, Nestola, F.
      Pages: 2235 - 2243
      Abstract: A single gem lithospheric diamond with five sulfide inclusions from the Udachnaya kimberlite (Siberia, Russia) has been analyzed non-destructively to track the growth conditions of the diamond. Sulfides are the most abundant mineral inclusions in many lithospheric diamond crystals and are the most favorable minerals to date diamond crystals by Re-Os isotope systematics. Our investigation used non-destructive, micro-techniques, combining X-ray tomography, X-ray fluorescence, X-ray powder diffraction, and Raman spectroscopy. This approach allowed us to determine the spatial distribution of the inclusions, their chemical and mineralogical composition on the microscale, and, finally, the paragenetic association, leaving the diamond host completely unaffected. The sample was also studied by X-ray diffraction topography to characterize the structural defects of the diamond and to obtain genetic information about its growth history. The X-ray topographic images show that the sample investigated exhibits plastic deformation. One set of {111} slip lamellae, corresponding to polysynthetic twinning, affects the entire sample. Chemical data on the inclusions still trapped within the diamond show they are monosulfide solid solutions of Fe, Ni and indicate a peridotitic paragenesis. Micro-X-ray diffraction reveals that the inclusions mainly consist of a polycrystalline aggregate of pentlandite and pyrrothite. A thorough analysis of the Raman data suggests the presence of a further Fe, Ni sulfide, never reported so far in diamonds: mackinawite. The total absence of any oxides in the sulfide assemblage clearly indicates that mackinawite is not simply a "late" alteration of pyrrhotite and pentlandite due to secondary oxidizing fluids entering diamond fractures after the diamond transport to the surface. Instead, it is likely formed as a low-temperature phase that grew in a closed system within the diamond host. It is possible that mackinawite is a more common phase in sulfide assemblages within diamond crystals than has previously been presumed, and that the percentage of mackinawite within a given sulfide assemblage could vary from diamond to diamond and from locality to locality.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6178
      Issue No: Vol. 102, No. 11 (2017)
  • The fate of ammonium in phengite at high temperature
    • Authors: Yang, Y; Busigny, V, Wang, Z, Xia, Q.
      Pages: 2244 - 2253
      Abstract: Nitrogen (N) is the main component of the atmosphere and is largely considered as a volatile element. However, most researchers now agree that a significant amount of N, in the form of ammonium (NH4+) substituting for K+ in some K-bearing minerals such as clays, micas, and feldspars, can be transferred to the deep Earth through subduction. The fate of ammonium in those minerals during subduction is still poorly known but is likely controlled by temperature and pressure pathways. In an attempt to contribute to understanding the fate of N during high-temperature processes, we carried out in situ high-temperature IR and Raman spectra measurements to investigate the rate and mechanism of NH4+ loss in phengite. We observed that a new OH band at 3425 cm–1 became prominent above 400 °C, and did not change with times during isothermal annealing at 500 and 700 °C. The N-H stretching band shifted to higher wavenumbers in the temperature interval from –150 to 20 °C, while linearly shifted to lower wavenumbers in the temperature interval from 20 to 500 °C and remained stable above 500 °C. The N-H bending band linearly shifted to lower wavenumbers in the temperature interval from –150 to 400 °C and remained stable. The K-O stretching frequency decreased with increasing temperature to 600 °C, and then remained stable. These processes were reversible until dehydration and ammonium loss from phengite starting at 800 °C. The results suggest that (1) at low temperatures, ammonium is ordered and hydrogen bonding between ammonium and the framework evolves during cooling; (2) at high temperatures, the N-H interatomic distance of NH4+ lengthens with increasing temperature until 500 °C. N-H bond subsequently no longer lengthens, accompanied by H transferring from N to neighboring O and forming a new OH band at 3425 cm–1. At 800 °C, H+ starts breaking from N and leaving others to form NH3 and OH–. This study has implications for evaluating the extent to which these minerals can preserve information regarding nitrogen behavior during high-temperature processes.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6094
      Issue No: Vol. 102, No. 11 (2017)
  • Parameterized lattice strain models for REE partitioning between amphibole
           and silicate melt
    • Authors: Shimizu, K; Liang, Y, Sun, C, Jackson, C. R. M, Saal, A. E.
      Pages: 2254 - 2267
      Abstract: The distribution of rare earth elements (REEs) between amphibole and silicate melt is important for understanding a wide variety of igneous and metamorphic processes in the lithosphere. In this study, we used published experimental REE and Y partitioning data between amphibole and silicate melt, the lattice strain model, and nonlinear least-squares regression method to parameterize key partitioning parameters in the lattice strain model (D0, r0, and E) as a function of pressure, temperature, and both amphibole and melt compositions. Two models, which give nearly identical results, are obtained in this study. In the first model, D0 depends on temperature and amphibole composition: it positively correlates with Ti content and negative correlates with temperature and Mg, Na, and K contents in the amphibole. In the second model, D0 depends solely on the melt composition: it positively correlates with Si content and negatively correlates with Ti and Ca contents in the melt. In both the mineral and melt composition models, r0 negatively correlates with the ferromagnesian content in the M4 site of the amphibole, and E is a constant. The very similar coefficients in the equations for r0 and best-fit values for E in the two models allow us to connect the two models through amphibole-melt phase equilibria. An application of our model to amphiboles in mantle xenoliths shows that observed major element compositional variations in amphibole alone can give rise to order of magnitude variations in amphibole-melt REE partition coefficients. Together with experimental data simulating fractional crystallization of arc magmas, out models suggest that: (1) REE partition coefficients between amphibole and melt can vary by an order of magnitude during arc magma crystallization due to variation in the temperature and composition of the amphibole and melt, and that (2) amphibole fractional crystallization plays a key role in depleting the middle REEs relative to heavy REEs and light REEs in arc magmas.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6110
      Issue No: Vol. 102, No. 11 (2017)
  • Unusual replacement of Fe-Ti oxides by rutile during retrogression in
           amphibolite-hosted veins (Dabie UHP terrane): A mineralogical record of
           fluid-induced oxidation processes in exhumed UHP slabs
    • Authors: Guo, S; Tang, P, Su, B, Chen, Y, Ye, K, Zhang, L, Gao, Y, Liu, J, Yang, Y.
      Pages: 2268 - 2283
      Abstract: The replacement of rutile by Fe-Ti oxides is a common phenomenon during the retrogression of eclogites. Here, we report an unusual case regarding the replacement of Fe-Ti oxides by rutile during greenschist-facies metamorphic overprinting of veins in amphibolites (retrograded eclogites) from the Dabie ultrahigh-pressure (UHP) terrane, eastern China. The veins mainly consist of plagioclase, Fe-Ti oxides, and quartz, which crystallized from a Ti-rich amphibolite-facies fluid that formed during exhumation of the eclogites. Two types of textures involving the replacement of Fe-Ti oxides by rutile are recognized in the veins: (1) the first type is characterized by the development of rutile coronas (Rt-C) and other silicates (high-Fe epidote, muscovite, and chlorite) around the external boundaries of the Fe-Ti oxide grains, and (2) the second type is characterized by the formation of symplectitic intergrowths of rutile (Rt-S) and magnetite after exsolved hemo-ilmenite (H-Ilm) lamellae in the Fe-Ti oxides. The micro-textures, mineral assemblages, and Zr-in-rutile thermometry indicate that both replacement reactions involved mineral re-equilibration processes in the presence of an infiltrating fluid phase at ~476–515 °C, taking place by an interface-coupled dissolution-precipitation mechanism. Thermodynamic modeling reveals that both replacement reactions occurred during oxidation processes under relatively high-oxygen fugacity (fO2) conditions, approximately 2.5–4.5 logfO2 units higher than the fayalite-magnetite-quartz (FMQ) reference buffer. In situ Sr isotopic analyses of epidote (Ep-C) coexisting with the Rt-C suggest that the infiltrating fluid involved in the greenschist-facies replacement reactions was externally derived from the surrounding granitic gneisses (the wall rocks of the amphibolites). Compared with the rutile in the UHP eclogites (Rt-E) and amphibolites (Rt-A), the Rt-C is characterized by distinctly lower contents of Nb (
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6120
      Issue No: Vol. 102, No. 11 (2017)
  • Crystallization experiments in rhyolitic systems: The effect of
           temperature cycling and starting material on crystal size distribution
    • Authors: da Silva, M. M; Holtz, F, Namur, O.
      Pages: 2284 - 2294
      Abstract: One of the various problems faced in experimental petrology is the fact that most experimental products obtained by crystallization experiments are too small, making their accurate identification by electron microprobe and laser ablation analyses very difficult. This problem is magnified when a highly polymerized starting material is used for experiments at low temperature (e.g., 700–800 °C). In this study, we present the results of crystallization experiments performed using a rhyolitic starting glass in which we test the potential of temperature cycling and pre-hydrated starting material to increase crystal size and discuss the effect of those variables on the attainment of chemical equilibrium. Experiments were performed at different temperatures (725 to 815 °C) and pressures (1 and 2 kbar), under water-saturated conditions (aH2O = 1; with aH2O being the water activity). During the experiments, temperature was either constant or cycled to ±15 °C around the target temperature during the first half of the runs. We used either a pre-hydrated (7 wt% H2O) rhyolitic glass or a dry rhyolitic glass to which 7 wt% H2O was added during capsule preparation.Our results differ between 1 and 2 kbar experiments. At 1 kbar, plagioclase and orthopyroxene were the main crystalline phases affected and temperature cycling (±15 °C) did not increase the crystal size of these phases. In contrast, if only the nature of the starting material is considered (dry glass vs. pre-hydrated), the use of a pre-hydrated starting material successfully increased the overall crystal size and decreased the crystal number density. At 2 kbar, plagioclase and amphibole were the main phases and the largest crystals were also obtained when pre-hydrated starting material was used. Contrary to experiments at 1 kbar, temperature cycling also increased the overall crystal size. The different effects of temperature cycling at 1 and 2 kbar are attributed (1) to the different cation diffusivities at 1 and 2 kbar caused by different melt water concentrations and (2) the negligible effect of temperature cycling at 1 kbar (±15 °C) is explained by little dissolution of phases, so that small crystals were already too large to be completely consumed by the dissolution process in the high temperature interval. The results demonstrate that temperature oscillation (depending on the amplitude) and the nature of the starting material (pre-hydrated vs. dry glass + water) are two parameters that can contribute to increase crystal sizes in experiments with rhyolitic melts. However, we also observed that the use of a pre-hydrated starting material increased the occurrence of zoned plagioclase crystals, which may indicate that chemical equilibrium was not perfectly reached.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-5981
      Issue No: Vol. 102, No. 11 (2017)
  • Dolomite dissociation indicates ultra-deep (>150 km) subduction of a
           garnet-bearing dunite block (the Sulu UHP terrane)
    • Authors: Su, B; Chen, Y, Guo, S, Liu, J.-B.
      Pages: 2295 - 2306
      Abstract: The dissociation of dolomite into magnesite and aragonite has been regarded as a useful indicator for ultrahigh-pressure (UHP) metamorphism. In this study we investigate an unusual texture involving magnesite and calcite intergrowths with dolomite relicts in a garnet-bearing dunite block from the Sulu UHP terrane, eastern China. The carbonate intergrowths typically occur as interstitial grains with low dihedral angles against surrounding olivines and have a dolomitic precursor composition. Our observations indicate that the carbonate intergrowths were initially inherited from the well-documented magnesite and aragonite assemblage after dolomite dissociation. The initial dolomite grains were likely to crystallize during the dolomitic melt metasomatism within the shallow lithospheric mantle. A series of experimental studies have well determined the equilibrium boundary of dolomite = magnesite + aragonite greater than 5 GPa along a wide temperature range, which provides direct evidence that the dunite block was subducted to depths greater than 150 km during the Triassic continental subduction. The preservation of magnesite and aragonite (now calcite) intergrowths without dolomite synthesis reaction during exhumation is probably due to the lack of fluid and rapid decompression from the peak stage to the calcite stability field. In this study, we suggest that dunite blocks from high-pressure and UHP terranes could have subducted to UHP conditions similar to garnet lherzolite and pyroxenite and were then entrained into slab slices rapidly en route to the surface.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-5982
      Issue No: Vol. 102, No. 11 (2017)
  • Microscopic strain in a grossular-pyrope solution anti-correlates with
           excess volume through local Mg-Ca cation arrangement, more strongly at
           high Ca/Mg ratio
    • Authors: Du, W; Walker, D, Clark, S. M, Li, X, Li, B.
      Pages: 2307 - 2316
      Abstract: Unit-cell volume and microstrain of Py40Gr60 garnets vary with synthesis temperature and annealing time, showing a strong negative correlation, as is also seen in another garnet solid solution, Py20Gr80. This anti-correlation is explained by local Ca-Mg cation arrangement in which Ca-Ca and Mg-Mg third-nearest-neighbor (Same 3NN = S3NN) pairs form at rates other than those expected from random Ca-Mg distribution. S3NN pairs cause microstrain (Bosenick et al. 2000) but allow more efficient packing than random Ca-Mg pairings that contribute to excess volume, hence smaller cell volumes correlate with more microstrain. Both longer annealing time and higher heating temperature cause more S3NN formation, larger microscopic strain, and smaller unit-cell volume. The anti-correlation of microstrain and excess volume is weaker in our previous study of pyrope-rich solutions (i.e., Py80Gr20, Du et al. 2016) because excess volume varies little from Ca-Ca S3NN pairings in pyrope-rich solutions, whereas Mg-Mg S3NN pairings in grossular-rich solutions studied here are effective at reducing excess volume. Heating to 600 °C under room pressure or cold hydrostatic compression to 10 GPa does not reset microstrain.Margules’ formulations for microstrain and volume as a function of Ca/Mg ratio captures these features, especially the two-peaked distribution of microstrain with composition discovered by Du et al. (2016). The similar two-peaked distributions of microstrain and excess energies derived from ab initio calculation with short-range ordering of Mg and Ca cations (Vinograd and Sluiter 2006) indicate that the macroscopic thermodynamic mixing properties of solid solutions are directly related to arrangement of cations with large size misfit. The observed changes of microstrain with annealing temperature suggest that mixing properties measured from our pyrope-grossular garnet solid solutions synthesized at same temperature can serve as better experimental constrains for computational work.
      PubDate: 2017-11-01T06:00:30-07:00
      DOI: 10.2138/am-2017-6117
      Issue No: Vol. 102, No. 11 (2017)
  • Ferruginous seawater facilitates the transformation of glauconite to
           chamosite: An example from the Mesoproterozoic Xiamaling Formation of
           North China
    • Authors: Tang, D; Shi, X, Jiang, G, Zhou, X, Shi, Q.
      Pages: 2317 - 2332
      Abstract: Berthierine and chamosite are iron-rich clay minerals that share similar chemical compositions. Berthierine forms at low temperature (25–45 °C) during early diagenesis and may transfer to chamosite at temperatures of ≥70 °C. Because the formation of berthierine and chamosite requires significant amount of Fe2+ supply, their presence in marine sediments is often used as a mineral proxy for ferruginous conditions in porewater. Recent studies reveal that the Precambrian oceans were characterized by pervasive ferruginous water-column conditions that may favor the formation of iron-rich clay minerals like berthierine and chamosite. To evaluate if ferruginous water-column conditions in the Precambrian ocean played a role on iron-rich clay mineral formation, we conducted an integrated petrographic, mineralogical, and geochemical study on the chamosite- and glauconite-bearing strata of the Mesoproterozoic Xiamaling Formation (~1.40–1.35 Ga) in North China. Petrographic, XRD, SEM, and EDS analyses show that the chamosites of the Xiamaling Formation was transferred from glauconite, with berthierine as an intermediate mineral phase during early diagenesis. Geochemical analyses indicate that a complete transformation from glauconite-dominated to chamosite-dominated end-members (samples) requires an addition of a large amount of Fe (16.9 wt%), Mg (2.4 wt%), and a small amount of Al (1.4 wt%), but a simultaneous release of Si (11.8 wt%) and K (6.0 wt%). Considering that the glauconite- and chamosite-bearing strata are devoid of iron-rich detrital minerals (e.g., biotite and iron oxides) and lack evidence of hydrothermal alteration, the required Fe2+ for glauconite-berthierine-chamosite transformation was most likely from Fe2+-rich (ferruginous) seawater, which may have promoted glauconite-berthierine transformation at the very early diagenetic stage when Fe2+ exchange between porewater and seawater was still available. This interpretation is consistent with the high FeHR/FeT (but low Fepy/FeHR), Fe/Al, and V/Al ratios from the hosting strata that support ferruginous depositional environments. Because most Precambrian strata have passed the oil window temperature (>50–150 °C), the preservation of berthierine would be rare and chamosite should be the representative iron-rich clay mineral. Thus, the abundance of chamosite in fine-grained, marine siliciclastic sediments may be used as a mineral indicator of ferruginous water-column conditions.
      PubDate: 2017-11-01T06:00:31-07:00
      DOI: 10.2138/am-2017-6136
      Issue No: Vol. 102, No. 11 (2017)
  • Charleshatchettite, CaNb4O10(OH)2{middle dot}8H2O, a new mineral from Mont
           Saint-Hilaire, Quebec, Canada: Description, crystal-structure
           determination, and origin
    • Authors: Haring, M. M. M; McDonald, A. M.
      Pages: 2333 - 2340
      Abstract: Charleshatchettite, CaNb4O10(OH)2·8H2O, is a new mineral related to franconite and hochelagaite, discovered on a fracture surface of a nepheline syenite at Mont Saint-Hilaire, Québec, Canada. The mineral occurs in white globules (~0.15–0.20 mm in diameter) composed of radiating crystals with individual crystals having average dimensions of ~0.002 x 0.010 x 0.040 mm. Crystals are euhedral, bladed (flattened on [100]), and are transparent to translucent. The mineral is associated with albite, quartz, muscovite, pyrrhotite, pyrite, ancylite-(Ce), and siderite. Charleshatchettite is inferred to be biaxial (–) with α' = ~1.72(2) and ' = ~1.82(2). Data from chemical analyses (SEM-EDS, n = 8): CaO 7.96 (7.04–8.63), MgO 0.24 (0.08–0.78), Al2O3 0.13 (b.d.–0.49), SiO2 1.04 (0.49–1.88), TiO2 3.64 (2.45–5.05), Nb2O5 68.07 (64.83–71.01), and H2O (calc) 22.96, total 104.04 wt% gives the average empirical formula: (Ca1.00Mg0.04)1.04(Nb3.62Ti0.32Si0.12Al0.02)4.08O10(OH)2·8H2O (based on 20 anions). This is similar to that of hochelagaite (CaNb4O11·nH2O), although the two are readily distinguished by their powder X-ray diffraction patterns. Results from single-crystal X-ray diffraction analysis give a = 21.151(4), b = 6.496(2), c = 12.714(3) Å, and β = 103.958(3)°, space group C2/c (no. 15). The crystal structure, refined to R = 5.64%, contains 1 Ca site, 2 distorted octahedral Nb sites, and 10 O sites. It consists of clusters of four edge-sharing Nb(O,OH)6 octahedra, linked through shared corners to adjacent clusters, forming layers of Nb(O,OH)6 octahedra. These alternate along [100] with layers composed of Ca(H2O)8 polyhedra, the two being linked together by H-bonding. Charleshatchettite is a late-stage mineral, interpreted to have developed through the interaction of low-T (
      PubDate: 2017-11-01T06:00:31-07:00
      DOI: 10.2138/am-2017-5926
      Issue No: Vol. 102, No. 11 (2017)
  • New Mineral Names,
    • Authors: Belakovskiy, D. I; Camara, F, Gagne, O. C.
      Pages: 2341 - 2347
      PubDate: 2017-11-01T06:00:31-07:00
      DOI: 10.2138/am-2017-NMN1021123
      Issue No: Vol. 102, No. 11 (2017)
  • Erratum
    • Pages: 2347 - 2347
      PubDate: 2017-11-01T06:00:31-07:00
      DOI: 10.2138/am-2017-E1021127
      Issue No: Vol. 102, No. 11 (2017)
  • Book Review: Non-Traditional Stable Isotopes
    • Authors: Matthews A.
      Pages: 2348 - 2348
      PubDate: 2017-11-01T06:00:31-07:00
      DOI: 10.2138/am-2017-676
      Issue No: Vol. 102, No. 11 (2017)
School of Mathematical and Computer Sciences
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