Subjects -> CHEMISTRY (Total: 986 journals)
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CHEMISTRY (715 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 19)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 34)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 2)
ACS Catalysis     Hybrid Journal   (Followers: 60)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 23)
ACS Combinatorial Science     Hybrid Journal   (Followers: 23)
ACS Macro Letters     Hybrid Journal   (Followers: 30)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 48)
ACS Nano     Hybrid Journal   (Followers: 416)
ACS Photonics     Hybrid Journal   (Followers: 17)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 31)
Acta Chemica Iasi     Open Access   (Followers: 8)
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 9)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 11)
Adsorption Science & Technology     Open Access   (Followers: 8)
Advanced Electronic Materials     Hybrid Journal   (Followers: 3)
Advanced Functional Materials     Hybrid Journal   (Followers: 72)
Advanced Science Focus     Free   (Followers: 6)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 1)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 94)
Advances in Chemical Science     Open Access   (Followers: 37)
Advances in Chemistry     Open Access   (Followers: 31)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Environmental Chemistry     Open Access   (Followers: 10)
Advances in Enzyme Research     Open Access   (Followers: 12)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 31)
Advances in Nanoparticles     Open Access   (Followers: 19)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Polymer Science     Hybrid Journal   (Followers: 49)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 19)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Science and Technology     Full-text available via subscription   (Followers: 15)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 5)
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  
Alchemy : Journal of Chemistry     Open Access   (Followers: 4)
Alchemy : Jurnal Penelitian Kimia     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 69)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 22)
American Journal of Chemistry     Open Access   (Followers: 36)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 15)
Anadolu University Journal of Science and Technology A : Applied Sciences and Engineering     Open Access  
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 203)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 318)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – 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: 5)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
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: 15)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 10)
Applied Spectroscopy     Full-text available via subscription   (Followers: 26)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 7)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 4)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 446)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 10)
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: 3)
Biomacromolecules     Hybrid Journal   (Followers: 24)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 200)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 88)
Bioorganic Chemistry     Hybrid Journal   (Followers: 9)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 26)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 4)
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: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Research     Hybrid Journal   (Followers: 23)
Carbon     Hybrid Journal   (Followers: 74)
Catalysis for Sustainable Energy     Open Access   (Followers: 10)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 11)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 14)
Cellulose     Hybrid Journal   (Followers: 13)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 2)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 23)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 81)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Physics Letters : X     Open Access   (Followers: 2)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 24)
Chemical Reviews     Hybrid Journal   (Followers: 246)
Chemical Science     Open Access   (Followers: 36)
Chemical Science International Journal     Open Access   (Followers: 1)
Chemical Technology     Open Access   (Followers: 54)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 21)
ChemInform     Hybrid Journal   (Followers: 9)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 209)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 19)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 24)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry Education Review     Open Access   (Followers: 2)
Chemistry in Education     Open Access   (Followers: 8)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 47)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 308)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 21)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access   (Followers: 1)
ChemSystemsChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal   (Followers: 1)
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: 12)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Ciencia     Open Access   (Followers: 1)
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 12)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 7)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 23)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Communications Chemistry     Open Access   (Followers: 2)
Communications Materials     Open Access   (Followers: 3)
Composite Interfaces     Hybrid Journal   (Followers: 9)
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: 2)

        1 2 3 4 | Last

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Canadian Mineralogist
Journal Prestige (SJR): 0.565
Citation Impact (citeScore): 1
Number of Followers: 7  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0008-4476 - ISSN (Online) 1499-1276
Published by GeoScienceWorld Homepage  [19 journals]
  • Cadwaladerite, Al 2 (H 2 O)(OH) 4 · n (Cl,OH – ,H 2 O), from Cerros
           Pintados, Chile, defined as a valid mineral species and the discreditation
           of lesukite
    • Authors: Peterson RC; Metcalf M, Kampf AR, et al.
      Abstract: AbstractCadwaladerite, described in 1941 as Al(OH)2Cl·4H2O, and lesukite, described in 1997 as Al2(OH)5Cl·2H2O, are very closely related chemically and structurally, but are found in very different environments. Cadwaladerite was found at the edge of a salar in Chile. Lesukite has been described from a volcanic fumarole and from burning coal seams. Both materials have cubic symmetry with a = 19.788 to 19.859Å. The crystal structure, common to both, consists of a rigid three-dimensional framework of edge- and corner-sharing Al(OH,H2O)6 octahedra that contains large interconnected cavities where loosely held Cl, OH, and H2O are located. The fact that Cl is loosely held within the structure is demonstrated by a dramatic reduction in Cl content after washing the material in distilled water, while the structural integrity is maintained. Herein, cadwaladerite is confirmed as a valid mineral species and lesukite is discredited because the only difference between the two materials is the loosely held extra-framework Cl, OH, and H2O. Cadwaladerite, Al2(H2O)(OH)4·n(Cl,OH,H2O) (Z = 48) takes precedence over lesukite based on the date of description. Material similar to cadwaladerite is found as a corrosion product on some types of nuclear fuel elements and is also closely related to the molecular species used in antiperspirant and water filtration.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • Ore mineralogy of the Chisel Lake Zn-Cu-Ag (+Au) VMS deposit in the Flin
           Flon – Snow Lake Domain, Manitoba, Canada
    • Authors: Alexandre P; Heine T, Fayek M, et al.
      Abstract: AbstractThe Chisel Lake deposit, in the Flin Flon – Snow Lake Mineral Belt in northern Manitoba, is characterized by an ore mineral assemblage dominated by pyrite and sphalerite, with minor chalcopyrite, galena, and pyrrhotite and trace amounts of other Cu-, Fe-, Sb-, Sn-, As-, Ni-, and Ag-bearing sulfides. Silver is hosted in a variety of Ag-bearing sulfides (chalcopyrite and freibergite–argentotennantite series) and its own sulfide (acanthite).The major elements chemical compositions of the ore sulfides define two populations of sphalerite (Fe-rich and Fe-poor), three populations of chalcopyrite (pure, Ag-rich, and Ag- and Sb-rich), and a typical galena, in addition to pyrite and pyrrhotite. Trace elements are dominated by Mn and Cd for sphalerite; Sn, Zn, and Ge for chalcopyrite; Se and Ni for pyrrhotite; and As and Co for pyrite. Formation temperature was best estimated, from the Fe and trace elements (Ga, Ge, Mn, and In) concentrations in sphalerite, at approximately 340 °C, with other methods giving less reliable temperature and pressure estimates.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • Cathodoluminescence and trace-element chemistry of quartz from Sudbury
           offset dikes: Observations, interpretations, and genetic implications
    • Authors: Wehrle EA; McDonald AM.
      Abstract: AbstractOffset dikes, radial and concentric fractures infilled with quartz diorite, are important hosts of Ni-Cu-PGE mineralization in the Sudbury area. To better understand their emplacement and evolution, the cathodoluminescence (CL) and trace-element chemistry of quartz were examined in quartz diorite from the Foy, Trill, Whistle, Hess, Parkin (North Range), and Copper Cliff (South Range) offsets. Although the potential causes of the CL response in quartz are considered, the primary focus was the qualitative textures and patterns, as these can provide valuable paragenetic information. Quartz from the North Range displays a strong blue luminescence dominated by homogenous and sharply zoned CL patterns, while that from the Copper Cliff offset displays a weak CL response. Locally recrystallized granoblastic quartz shows diffuse concentric zoning and other heterogeneous CL patterns. Trace-element EPMA-WDS analyses indicate that quartz from the Foy, Trill, and Whistle offsets is enriched in Al (30–600 ppm) and Ti (50–520 ppm) as compared to Fe (<25–490 ppm), while quartz from the Parkin and Hess offsets is enriched in Fe (270–700 ppm) as compared to Ti (44–211 ppm) and Al (95–250 ppm). In contrast to the North Range offsets, quartz from Copper Cliff has low Al concentrations (30–85 ppm) and very low Ti concentrations (<25 ppm). Application of the Ti-in-quartz geothermometer indicates that quartz from the North Range offsets crystallized above 600 °C, while that from the Copper Cliff offset crystallized below 600 °C. The CL responses and trace-element compositions of anhedral quartz from the North Range offsets are consistent with primary crystallization of quartz from magmatic quartz diorite, while those of the granoblastic quartz record dynamic recrystallization and Ostwald ripening. Copper Cliff quartz is anomalous in its CL response, trace-element content, and crystallization temperature, which may reflect overprinting during regional metamorphism of the South Range of the Sudbury Igneous Complex. Quartz CL is demonstrated to be an important tool for discerning and discriminating between paragenetic processes related to the formation of the offset dikes and has clear applications to the study of other quartz-bearing igneous rocks in the Sudbury area.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • The genesis of agates and amethyst geodes
    • Authors: Kigai IN.
      Abstract: AbstractPractically all aspects of agate genesis generate debate. The time is ripe to clarify the most important enigmas concerning the environments of formation of agates and the related famous amethyst geodes of Brazil and Uruguay. Agates form over a wide range of temperatures, from those of basaltic and andesitic melts (about 1100 °C) down to about 50 °C, and at rather low pressures. Their formation in liquid mafic magmas is indicated by a correlation between (1) the orientation of amygdules and the inclination of onyx banding in them and (2) the attitude of amygdules in the lava flow layers. The correlation arises because lava moves at a different rate close to and far from the upper and lower rims of a flow. The alkaline supercritical fluid fills gas vesicles in lavas and dissolves silica, mainly, from ambient lava or rock to produce a silica sol. If the pressure on the fluid causes percolation of water from amygdules, the sol coagulates on the walls of the vesicle to form a concentric lining. If the pressure in amygdules falls below the maximum osmotic pressure of a sol (about 0.1 MPa for a silica sol), percolation of fluid stops, and coagulation leads to the formation of horizontal onyx banding. Multiple repetitions of precipitation of various gel layers can be caused by overlapping fresh flows upon the cooling older agate-bearing lava flow. In a submarine setting, phase separation of the fluid and the formation of a film of gel between vapor (or diluted solution) and brine stimulate the osmotic processes, which result in growth of hollow membrane tubes and branching moss-like arrays at the bottom of amygdules. Some agates exhibit numerous channels as a result of repeated extrusion of fluid or gel from inner zones to the periphery of amygdules that were compressed under the burden of new flows. Previously, such channels were interpreted to be feeding channels for silica supply in amygdules. Periodic compression of amygdules after percolation of fluid from them requires no additional supply of silica because the volume of the amygdules is reduced in proportion to the loss of fluid. The concentric and horizontal banding and mossy textures of agates from the lithophysae of felsic volcanic rocks were created during active volcanism as well. The agates from dissolution-induced cavities in carbonate rocks and the famous amethyst druses of Brazil and Uruguay formed at the moderate temperatures associated with low-grade burial metamorphism, as indicated by the lack of moss textures and onyx banding.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • Rinkite-(Ce) in the nepheline syenite pegmatite from the Saima alkaline
           complex, northeastern China: Its occurrence, alteration, and implications
           for REE mineralization
    • Authors: Wu B; Wen H, Bonnetti C, et al.
      Abstract: AbstractThe nepheline syenite pegmatite in the Saima alkaline complex in northeastern China is characterized by REE mineralization, mainly rinkite-(Ce) and associated alteration minerals. As the most abundant REE-bearing mineral in the pegmatite, rinkite-(Ce) closely coexists with microcline, nepheline, natrolite, and calcite. Some rinkite-(Ce) grains show compositional sector-zonation, in which the inner core displays relatively high Ti, Ca, and Sr concentrations, but low Zr, REE, and Na contents. Primary rinkite-(Ce) has undergone multiple episodes of fluid interactions, and accordingly, from weak to strong, three different mineral assemblages of hydrothermal alteration can be summarized: (1) rinkite-(Ce) + secondary natrolite ± K-feldspar ± minor fluorbritholite-(Ce); (2) rinkite-(Ce) relics + secondary natrolite + K-feldspar + fluorbritholite-(Ce) + unidentified Ca-Ti silicate mineral + fluorite and calcite; and (3) pseudomorphs after rinkite-(Ce). The pseudomorphs can be divided into two groups characterized by distinct mineral associations: (1) Ca-bearing strontianite + fluorbritholite-(Ce) + natrolite + fluorite + calcite coexisting with silicate minerals; and (2) calcite + fluorite + fluorbritholite-(Ce) + rinkite-(Ce) relics ± Ca-bearing strontianite ± ancylite-(Ce) associated with a calcite matrix. These alteration mineral assemblages are evidence of magmatic-derived alkali metasomatism due to an alkali-CO2-F-rich fluid and Ca-metasomatism due to a different, externally derived Sr- and Ca-rich fluid. The metasomatic events acted as the potential driving force for the rinkite-(Ce) dissolution and pseudomorph-forming process. The high concentration of rinkite-(Ce) in the nepheline syenite pegmatite results from the fractional crystallization of the Saima CO2-rich alkaline silicate magma, and the successive alterations of rinkite-(Ce) attest to the important role played by hydrothermal fluids in controlling the remobilization of REE and the crystallization of secondary rare earth minerals.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • Alkali sulfates with aphthitalite-like structures from fumaroles of the
           Tolbachik Volcano, Kamchatka, Russia. I. MetathÉnardite, a natural
           high-temperature modification of Na 2 SO 4
    • Authors: Pekov IV; Shchipalkina NV, Zubkova NV, et al.
      Abstract: AbstractA new mineral, metathénardite, ideally Na2SO4, the high-temperature hexagonal dimorph of thénardite, a natural analogue of the synthetic phase Na2SO4(I), was found in the sublimates of active fumaroles at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure eruption, Tolbachik volcano, Kamchatka, Russia. The holotype originates from the Glavnaya Tenoritovaya fumarole in which metathénardite is associated with hematite, tenorite, fluorophlogopite, sanidine, anhydrite, krasheninnikovite, vanthoffite, glauberite, johillerite, and lammerite. The cotypes 1 and 2 are from the Arsenarnaya (with hematite, tenorite, fluorophlogopite, sanidine, euchlorine, wulffite, anhydrite, fluoborite, johillerite, nickenichite, calciojohillerite, badalovite, tilasite, cassiterite, and pseudobrookite) and the Yadovitaya (with tenorite, euchlorine, fedotovite, dolerophanite, langbeinite, krasheninnikovite, anhydrite, and hematite) fumaroles, respectively. All specimens with metathénardite were collected from areas with temperatures of 350–400 °C. Metathénardite forms hexagonal tabular, lamellar, or dipyramidal crystals (forms: {001}, {100}, {102}, and {201}) up to 3 mm combined in crusts up to several hundred cm2 in area. The mineral is transparent to semitransparent, colorless, white, light-blue, greenish, yellowish, grayish or brownish, with vitreous luster. Dmeas. = 2.72(1), Dcalc. = 2.717 g/cm3. Metathénardite is optically uniaxial (–), ω = 1.489(2), ε = 1.486(2). The empirical formulae are (Na1.92K0.05Ca0.02Zn0.01)[S0.99O4] (holotype), (Na1.54K0.22Ca0.09Cu0.01Mg0.01)[S1.00O4] (cotype 1), and Na1.65K0.11Ca0.05Cu0.04Mg0.01)[S1.01O4] (cotype 2). Admixed K and bivalent cations probably stabilize the hexagonal aphthitalite-like structure of metathénardite at room temperature. The crystal structure was solved using single crystals of all three samples, R1 = 0.0852, 0.0452, and 0.0449 for holotype and cotypes 1 and 2, respectively. The space group is P63/mmc, and the unit-cell parameters of the holotype are a = 5.3467(9), c = 7.0876(16) Å, V = 157.47(6) Å3, and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 4.667(27)(100), 3.904(89)(101), 3.565(33)(002), 2.824(94)(102), 2.686(100)(110), and 1.939(35)(202). Metathénardite and thénardite clearly differ from one another in X-ray diffraction data and infrared and Raman spectra.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • Microthermometric behavior of crystal-rich inclusions in spodumene under
           confining pressure
    • Authors: Anderson AJ.
      Abstract: AbstractA hydrothermal diamond anvil cell (HDAC) was used to observe the microthermometric behavior of solid + liquid + vapor inclusions in spodumene from the Tanco pegmatite, Manitoba, under confining pressure. At 25 °C, these inclusions commonly contain a carbonate mineral (zabuyelite, rarely calcite or nahcolite), quartz, a phyllosilicate (cookeite), and an aqueous carbonic fluid phase. Heating spodumene-hosted inclusions to temperatures between 600 and 680 °C in a HDAC resulted in total or partial dissolution of the contained solid phases, followed by homoepitaxial growth of new spodumene on the inclusion walls, which reduced the inclusion volume by up to 31%. At room temperature, the homogenized inclusions contain only an aqueous fluid phase, CO2 liquid, and CO2 vapor. Inclusions that failed to homogenize at 680 °C, or leaked during heating, contain partially dissolved minerals with or without an aqueous carbonic fluid.The volume of spodumene formed within an inclusion during experimental re-heating, as determined by the difference in inclusion size before and after total dissolution of the contained solid phases, was used to estimate the volume of zabuyelite, quartz/cristobalite, and cookeite produced by the reaction The relative volumes of the calculated reaction products approximate the proportions of zabuyelite, quartz/cristobalite, and cookeite in inclusions prior to heating. The absence of silicate glass in the quenched homogenized inclusions indicates that they do not represent the crystallized products of an entrapped hydrous silicate melt that wetted the surface of spodumene during its growth. Large changes in inclusion volume and composition during experimental re-heating shows that the inclusions are neither isochoric nor isoplethic systems and as such are unsuitable for estimating the P-T conditions of trapping. Readers should therefore exercise caution when using thermobaric estimates of pegmatite crystallization inferred from microthermometric measurements of presumably primary melt inclusions in spodumene.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • Fluorapophyllite-(Cs), CsCa 4 (Si 8 O 20 )F(H 2 O) 8 , a new
           apophyllite-group mineral from the Darai-Pioz Massif, Tien-Shan, northern
           Tajikistan
    • Authors: Agakhanov AA; Pautov LA, Kasatkin AV, et al.
      Abstract: AbstractFluorapophyllite-(Cs) (IMA 2018-108a), ideally CsCa4(Si8O20)F(H2O)8, is an apophyllite-group mineral from the moraine of the Darai-Pioz glacier, Tien-Shan, Northern Tajikistan. Associated minerals are quartz, pectolite, baratovite, aegirine, leucosphenite, pyrochlore, neptunite, fluorapophyllite-(K), and reedmergnerite. Fluorapophyllite-(Cs) is a hydrothermal mineral. It is colorless and has a vitreous luster and a white streak. Cleavage is perfect; it is brittle and has a stepped fracture. Mohs hardness is 4.5–5. Dmeas. = 2.54(2) g/cm3, Dcalc. = 2.513 g/cm3. Fluorapophyllite-(Cs) is unixial (+) with refractive indices (λ = 589 nm) ω = 1.540(2), ε = 1.544(2). It is non-pleochroic. Chemical analysis by electron microprobe gave SiO2 48.78, Al2O3 0.05, CaO 22.69, Cs2O 10.71, K2O 1.13, Na2O 0.04, F 1.86, H2Ocalc. 14.61, –O=F2 –0.78, sum 99.09 wt.%; H2O was calculated from crystal-structure analysis. The empirical formula based on 29 (O + F) apfu, H2O = 8 pfu, is (Cs0.75K0.24)Σ0.99(Ca3.99Na0.01)Σ4(Si8.01Al0.01)Σ8.02O20.03F0.97(H2O)8, Z = 2. The simplified formula is (Cs,K)(Ca,Na)4(Si,Al)8O20F(H2O)8. Fluorapophyllite-(Cs) is tetragonal, space group P4/mnc, a 9.060(6), c 15.741(11) Å, V 1292.10(19) Å3. The crystal structure has been refined to R1 = 4.31% based on 498 unique (Fo > 4σF) reflections. In the crystal structure of fluorapophyllite-(Cs), there is one [4]T site occupied solely by Si, <T–O> = 1.615 Å. SiO4 tetrahedra link to form a (Si8O20)8– sheet perpendicular to [001]. Between the Si–O sheets, there are two cation sites: A and B. The A site is coordinated by eight H2O groups [O(4) site], A–O(4) = 3.152(4) Å; the A site contains Cs0.75K0.24□0.01, ideally Cs apfu. The Cs–O bond length of 3.152 Å is definitely larger than the K–O bond length of 2.966–2.971 Å in fluorapophyllite-(K), KCa4(Si8O20)F(H2O)8. The [7]B site contains Ca3.99Na0.01, ideally Ca4apfu; <B–φ> = 2.417 Å (φ = O, F, H2O). The Si–O sheets connect via A and B polyhedra and hydrogen bonding; two H atoms have been included in the refinement. Fluorapophyllite-(Cs) is isostructural with fluorapophyllite-(K). Fluorapophyllite-(Cs) is a Cs-analogue of fluorapophyllite-(K).
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
  • The local structure of Ta(v) aqua ions in high temperature fluoride- and
           chloride-bearing solutions: Implications for Ta transport in
           granite-related postmagmatic fluids
    • Authors: Anderson AJ; Mayanovic RA, Lee T.
      Abstract: AbstractThe local structure of Ta(V) in high-temperature fluoride- and chloride-bearing acidic solutions was investigated using in situ X-ray absorption spectroscopy (XAS). All XAS spectra were collected from two solutions, designated A and B, at beamline ID-20-C at the Advanced Photon Source, Argonne National Laboratory. Spectra were collected from solution A at 350 and 400 °C and from solution B at 25, 360, and 400 °C after the solutions were sealed in a hydrothermal diamond anvil cell. Solution A was prepared by dissolving Ta2O5 powder in 5% HF solution; solution B consisted of TaCl5 dissolved in 2% HF. The dominant tantalum species in solution A at elevated temperatures was TaF83–. In contrast, TaCl6–, which was the dominant complex in solution B at room temperature, disappeared as hydroxide complexes with an average ligand number between 5 and 7 became the dominant species at 350 and 400 °C. The XAS results confirm the previously recognized effect of fluoride activity on Ta speciation in hydrothermal fluids and suggest that both fluoride and hydroxide complexes play an important role in the transport of Ta in acidic fluoride-bearing solutions involved in the formation of mineralized mica-rich replacement units in granitic pegmatites.
      PubDate: Sat, 30 Nov 2019 00:00:00 GMT
       
 
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