Journal articles on the topic 'Alkali Aluminyls'
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1
Frost, Carol D., and Fabio A. Da Prat. "Petrogenetic and tectonic interpretation of strongly peraluminous granitic rocks and their significance in the Archean rock record." American Mineralogist 106, no. 8 (August 1, 2021): 1195–208. http://dx.doi.org/10.2138/am-2022-8001.
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Abstract Strongly peraluminous granitic rocks (SPG), defined by an aluminum saturation index ≥1.1, become abundant in the rock record in the Neoarchean. This study identifies three different varieties of Neoarchean SPG in the Archean Wyoming Province, U.S.A. These include calcic SPG, represented by the Webb Canyon Gneiss and Bitch Creek Gneiss of the Teton Range; calc-alkalic to alkali-calcic suites composed entirely of SPG, including the Rocky Ridge garnet granite gneiss of the northern Laramie Mountains and the Bear Mountain granite in the Black Hills; and calc-alkalic to alkali-calcic suites that include both weakly and strongly peraluminous granitic rocks, such as the Mount Owen batholith, Wyoming batholith, and Bears Ears granite. Although the petrogenesis of all the SPG suites involves partial melting of crustal sources, the composition of those sources, the melting conditions, and the tectonic settings vary. The calcic suites originate by dehydration melting or water excess melting of hornblende-plagioclase rocks at relatively high temperature. The suites composed entirely of SPG formed by partial melting of metasedimentary rocks by reactions involving muscovite at lower temperatures. Suites with both weakly and strongly peraluminous granite may form by partial melting of metasedimentary rocks by reactions involving biotite or by assimilation of aluminous melts of felsic crust by differentiated calc-alkalic magma. Most of the Wyoming SPG appear to have formed in collisional orogens, but SPG of the Wyoming batholith and Bears Ears granite are associated with continental arc magmatism. The appearance of SPG in the Neoarchean rock record marks the time when subduction enabled the formation of strong, thick, increasingly felsic continental crust, which in turn allowed the development of a mature, clastic sedimentary cover. Lateral movement of crustal blocks led to collisional orogeny, SPG magma genesis, and the formation of the first supercontinents.
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Gundusharma, U. M., and E. A. Secco. "New positive mixed alkali and mixed anion effects on fast Na+ ion conductivity in Na2SO4." Canadian Journal of Chemistry 65, no. 6 (June 1, 1987): 1205–8. http://dx.doi.org/10.1139/v87-202.
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The ac conductivity data for the binary alkali sulfate Rb+:Na2SO4 reveal a new positive mixed alkali effect in contrast to the so-called mixed alkali effect observed in β-aluminas. The binary alkali sulfate Rb+:Li2SO4 exhibits conductivity behavior intermediate between the two mixed alkali effects. A new positive mixed anion effect is also reported for the [Formula: see text] system. The higher Na+ conductivity in the Rb+:Na2SO4 and [Formula: see text] solid solutions is attributed to lattice expansion in a hexagonal structure effected by the larger radius isovalent guest ion and is interpreted in terms of a percolation type of transport mechanism.
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Zhang, Jie, Qiong Qiong Li, and Yu Qiang Xiong. "The Influence Factors of Compressive Strength and Production of Mineral Polymer of Aluminum Rocks in Xiuwen County, Guizhou Province, China." Advanced Materials Research 690-693 (May 2013): 1086–90. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1086.
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Aluminous rocks from Xiuwen County, Guizhou are the main raw materials, mixed some kaolin mineral. Water glass and alkaline activators are used to product polymer materials, the main experimental indicators are the compressive strength. Here, the studies on amount of water glass and alkaline activator, solid-liquid ratio, amount of kaolin and effects on compressive strength of Geopolymer have been proceeded respectively. The result shows that: the highest compressive strength of geopolymers is17.94 Mpa, with aluminous rock 40g, solid-liquid ratio 2.2, water glass12g and alkali activator 2.01g, as well as kaolin 18.02g.
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Yagüe Viana, Andrés, and Enric Vázquez Ramonich. "Carbonatación de morteros de cemento aluminoso en diversas condiciones de alcalinidad." Materiales de Construcción 45, no. 237 (March 30, 1995): 31–36. http://dx.doi.org/10.3989/mc.1995.v45.i237.566.
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Fernández-Carrasco, L., F. Puertas, M. T. Blanco-Varela, and T. Vázquez. "Nuevos avances en la carbonatación del cemento aluminoso. Hidrólisis alcalina." Materiales de Construcción 49, no. 253 (March 30, 1999): 47–55. http://dx.doi.org/10.3989/mc.1999.v49.i253.457.
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Feng, Xiao Xin, Yuan Jia, and Chen Guang Hu. "Effect of Admixtures Rich in Aluminium on Expansion due to Alkali-Silica Reaction." Applied Mechanics and Materials 268-270 (December 2012): 806–10. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.806.
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The effects of Al2O3 and Al(OH)3 on expansion due to alkali-silica reaction (ASR) were tested by using Accelerated Mortar Bar Test and through prolonging the curing age, and the ffect was compared with silicon fume and fly ash. The results show that ASR can be inhibited effectively by proper content of silicious admixtures within 14 days, but can not in long term, while it can be inhibited by proper content of Al2O3 and Al(OH)3 not only within 14 days but also in long term. The composite of silicious admixtures and aluminous admixtures has synergetic effect on inhibiting ASR, and there exists a value of Al2O3/SiO2 with which ASR is suppressed best. For the composite, ASR is suppressed mainly by silicious admixtures in early age and mainly by aluminous admixtures in long term.
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Aryanto, Noor C. D., and E. Suparka. "THE PETROLOGY CHARACTERISTIC OF GRANITOID ROCK BASED ON GEOCHEMICAL ANALYSIS OF BAJAU CAPE COAST AND ITS SURROUNDING, WEST KALIMANTAN." BULLETIN OF THE MARINE GEOLOGY 28, no. 1 (February 15, 2016): 13. http://dx.doi.org/10.32693/bomg.28.1.2013.51.
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The aim of this study is to identify of petrology characteristic based on geochemical analysis in order to know the granitoid rock type. Administratively, the study area is in the City and District of Singkawang, West Kalimantan Province, at coordinate 108°48'30†- 109°1'30†E and 0°40'30†- 0°54'30†N and, situated ± 145 km to the north of Pontianak City. The outcrop of granitoid along Bajau Cape coast and its surrounding, had been analyzed petrographically and geochemically using AAS method. Based on analysis of five samples show that the ratio mole of Al2O3/(CaO+Na2O +K2O) > 1 ranged between 1.12 and 1.7, while the rest of three samples are moderately aluminous, with a ratio value between 0.5 and 1.0. The ratio between K2O and (K2O+Na2O+CaO) ranges 0.07 to 0.55 (moderate) that forms alkali feldspar normative ranges from 3.8 to 15.89 wt%. This ratio shows that granite alkali feldspar is classified to be calc-alkaline series. Petrographically, this rock is porfiritic texture, hollocrystalline, granular hypodiomorphic and biotite present as phenocryst, yellowish brown, euhedral, thin and platy. The content of oxides element (Na2O and MgO) tend to decrease, whereas of other oxides elements, namely Al2O3, TiO2, K2O, FeO and CaO increased, parallel with the raising of SiO2. Therefore, the Singkawang Granitoid can be grouped as alkali feldspar granite, syeno-granite and quartz monzonite.
Keywords: petrography, geochemstry, major elements, calc-alcaline affinity, granitoid type and Bajau Coast, West Kalimantan.
Penelitian ini bertujuan untuk mengidentifikasi karakteristik petrologi, berdasarkan analisa geokimia sehingga jenis batuan granitoidnya dikenali. Secara administratif, daerah penelitian termasuk ke dalam Kota dan Kabupaten Singkawang, Provinsi Kalimantan Barat, pada koordinat 108°48'30†- 109°1'30†BT and 0°40'30†- 0°54'30†LU dan terletak ± 145 km, arah utara dari Kota Pontianak. Singkapan batuan granitoid sepanjang pantai Tanjung Bajau dan sekitarnya telah dianalisis secara petrografi dan geokimia dengan menggunakan AAS. Berdasarkan 5 contoh yang dianalisa menunjukan perbandingan mol Al2O3/(CaO+Na2O +K2O) > 1, yakni berkisar antara 1,12-1,7, sedangkan 3 contoh sisanya bersifat peraluminus sedang, dengan nilai ratio antara 0.5-1.0. Perbandingan antara K2O dan (K2O+Na2O+CaO) berkisar antara 0,07-0,55 (sedang) yang membentuk alkali normatif feldspar berkisar 3,84 – 15,89% (berat). Perbandingan tersebut menunjukan batuan Granit alkali feldspar yang tergolong dalam seri batuan kalk-alkali. Secara petrografi, batuan tersebut menunjukkan tekstur porfiritik, holokristalin, hipidiomorfik granular dengan biotit hadir sebagai fenokris, coklat kekuningan, euhedral, pipih dan sedikit berlembar. Kandungan unsur oksida (Na2O dan MgO) cenderung mengalami penurunan, sedangkan unsur oksida lainnya, yaitu Al2O3, TiO2, K2O, FeO dan CaO mengalami kenaikan sejalan dengan makin bertambahnya SiO2. Maka dengan demikian Granitoid Singkawang dapat dikelompokan menjadi granit alkali feldspar, syenit-granit dan kuarsa-monsonit.
Kata kunci: Petrografi, geokimia, senyawa utama, afinitas kalk-alkalin, batuan granitoid dan Pantai Bajau, Kalimantan Barat.
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Tan, A. "Structural determinations in mixed-alkali, mixed phase (β,β″)-aluminas." Solid State Ionics 24, no. 2 (July 1987): 129–35. http://dx.doi.org/10.1016/0167-2738(87)90021-x.
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BELL, M., M. SAYER, and P. NICHOLSON. "Ion exchange of mixed alkali ion, mixed phase (β,β″) aluminas." Solid State Ionics 18-19 (January 1986): 672–76. http://dx.doi.org/10.1016/0167-2738(86)90240-7.
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Mikhailova, Julia A., Yakov A. Pakhomovsky, Natalia G. Konopleva, Andrey O. Kalashnikov, and Victor N. Yakovenchuk. "Fluorine Controls Mineral Assemblages of Alkaline Metasomatites." Minerals 12, no. 9 (August 25, 2022): 1076. http://dx.doi.org/10.3390/min12091076.
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In the Khibiny and Lovozero alkaline massifs, there are numerous xenoliths of the so-called ‘aluminous hornfelses’ composed of uncommon mineral associations, which, firstly, are ultra-aluminous, and secondly, are highly reduced. (K,Na)-feldspar, albite, hercynite, fayalite, minerals of the phlogopite-annite and cordierite-sekaninaite series, corundum, quartz, muscovite, sillimanite, and andalusite are rock-forming minerals. Fluorite, fluorapatite, ilmenite, pyrrhotite, ulvöspinel, troilite, and native iron are characteristic accessory minerals. The protolith of these rocks is unknown. We studied in detail the petrography, mineralogy, and chemical composition of these rocks and believe that hornfelses were formed as a result of the metasomatic influence of foidolites. The main reason for the formation of an unusual aluminous association is the high mobility of aluminum promoted by the formation of fluid expelled from foidolites of the Na-Al-OH-F complexes. Thus, it is fluorine that controls the mobility of aluminum in the fluid and, consequently, the mineral associations of alkaline metasomatites. The gain of alkalis and aluminum to rocks of protolith was the reason for the intense crystallization of (K,Na)-feldspar. As a result, a SiO2 deficiency was formed, and Si-poor, Al-rich silicates and/or oxides crystallized.
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Hattori, T. "Reflection spectra of alkali β″-aluminas in ultraviolet and vacuum-ultraviolet regions." Solid State Ionics 79 (July 1995): 30–33. http://dx.doi.org/10.1016/0167-2738(95)00025-2.
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Marcelli, Augusto, Annibale Mottana, and Giannantonio Cibin. "Next-near-neighbour interactions with Al in Li+- and Rb+-exchanged Na+β-aluminas, detected by synchrotron X-ray absorption spectroscopy." Journal of Applied Crystallography 33, no. 2 (April 1, 2000): 234–42. http://dx.doi.org/10.1107/s0021889899015654.
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Synchrotron X-ray absorption near-edge structure (XANES) spectroscopy studies have been carried out on the electronic and crystal structure environments around the Al atom in Na+β-alumina and in two β-aluminas with Na+exchanged by Li+and Rb+. The aim is to define the type of interaction, if any, existing between the Al located in the `spinel block' and the fast-conducting cations in the `conduction plane'. Na+β′′-alumina has also been studied for comparison. All β-alumina spectra differ from that of α-alumina (corundum) by showing additional features due to the presence of tetrahedral Al. Moreover, they all show a much greater degree of local disorder. There are definite, but small, interactions between tetrahedral Al (and, possibly, also octahedral Al) in the `spinel block' and the Na+and Rb+cations in the `conduction plane'; Na+and Rb+β-aluminas have similar AlK-edge XANES features, but with intensities that change in relation to the weight of the `conduction plane' atom. Despite differences in composition and structure, Na+β′′-alumina shows the same behaviour, thus confirming the substantial similarity of the Al local environments. Li+-exchanged β-alumina has an AlK-edge XANES spectrum that apparently differs from all others, but actually conveys the same basic information. Indeed, interaction between Al and Li is much greater than in any other β-alumina because Li+moves laterally off the `conduction plane' to become close to a facing tetrahedral Al, and strongly interacts with it. Thus, this study also draws attention to the fact that β-aluminas react differently to alkali exchange.
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Vu, Hao Thi, and Hieu Trung Pham. "Geochemical characteristics of Chu Lai body granitoids in Nui Thanh, Quang Nam." Science and Technology Development Journal - Natural Sciences 2, no. 4 (August 14, 2019): 191–201. http://dx.doi.org/10.32508/stdjns.v2i4.828.
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Chu Lai body granitoid typically had the gneiss structure. Petrography inclueded biotite and two-mica granitogneiss. The rock consisted of quartz (25 – 30%), plagioclase (28 – 30%), akaline feldspar (30 – 32%), biotite (7 – 8%) and musscovite (3 – 5%). Accessory minerals were zircone, apatite, garnet, etc. Geochemical characteristics were typically high SiO2 (73.89 – 74.38 wt%); high total amount of alkali (Na2O + K2O ̴ 8.28 – 8.89%). Aluminous saturation indexs - ASI (Al2O3/CaO + Na2O + K2O) are more than 1. They have enrichment of the lipthophile elements with high Cs, Rb and Pb indexs; negative anomalies were Nb, Ta and strong Eu, specially. Eu/Eu* values were very low (0.041 – 0.056). The petrographic and geochemical charecteristics showed that Chu Lai rocks were S-granite, formed during the collision tectonic between Indochina and South China block in the early Paleozoic.
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Emeleus, C. H. "The Tertiary lavas and sediments of northwest Rhum, Inner Hebrides." Geological Magazine 122, no. 5 (September 1985): 419–37. http://dx.doi.org/10.1017/s0016756800035342.
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AbstractSeveral small outliers of Tertiary lavas and sediments rest with strong unconformity on a buried landscape eroded from Torridonian sediments and Tertiary granophyre. Erosion continued during the period of sediment and lava accumulation. Four formations are recognized; these are, in order of increasing age, the Orval Formation (hawaiite and basaltic hawaiite lavas), the Guirdil Formation (icelandite lavas, interbedded conglomerates), the Upper Fionchra Formation (tholeiitic basaltic andesite lavas, hyaloclastite deposits, basal conglomerate) and the Lower Fionchra Formation (alkali and transitional basalt, basaltic hawaiite and hawaiite lava flows, basal conglomerate); each is separated by an erosional interval. Clasts in the conglomerates reveal a history of erosion of a terrain exposing gneisses, Torridonian sediments, igneous rocks derived from the Rhum Tertiary Central Complex (including allivalites), and Tertiary lavas of local origin but also including, in the oldest conglomerates, tholeiitic basalts not now preserved on or near Rhum. Prior to and during lava and sediment accumulation, erosion on Rhum had cut down to a level similar to that of the present day, although not to the extent that high-grade thermally altered rocks, which are a marked feature of the Central Complex, were being eroded in any quantity. A sequence of east–west trending valleys, possibly initiated on the line of the earlier Main Ring Fault, drained the area of the Central Complex which then, as now, must have been high ground. Small lakes occasionally formed in the valleys allowing the accumulation of fine-grained sediment with plant remains, and promoting the formation of hyaloclastite deposits when buried by later flows. No source for any of the lava formations is preserved on Rhum; they are thought to have come from feeders north of Rhum, possibly near Canna, and to have ponded against the hills and valleys near and in the Central Complex.The oldest tholeiitic lavas, not now found in situ, were followed by alkali and transitional flows compositionally similar to the Skye Main Lava Series but characteristically feldsparphyric; the most mafic also contain phenocrysts of magnesian olivine (with included Cr-Al-rich spinels) and aluminous spinel. Both the early alkalic/transitional basalts and the youngest hawaiites and basaltic hawaiites equilibrated at pressures < 9 kb; the tholeiitic basaltic andesites and icelandites equilibrated at relatively shallows depths.Apart from a few N–S to NW–SE-trending basalt dykes, the lava formations represent the youngest Tertiary igneous event on Rhum.
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Jayaraman, V., G. Periaswami, and T. R. N. Kutty. "Extended stability ranges of β-aluminas with increasing ionic radii of metal alkali ions." Materials Letters 45, no. 2 (August 2000): 71–78. http://dx.doi.org/10.1016/s0167-577x(00)00079-3.
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Chatterjee, A. K. "Re-examining the prospects of aluminous cements based on alkali-earth and rare-earth oxides." Cement and Concrete Research 39, no. 11 (November 2009): 981–88. http://dx.doi.org/10.1016/j.cemconres.2009.07.027.
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Susnitzky, D. W., S. McKeman, and C. B. Carter. "Characterization of potassium aluminates in an α-Al2O3 matrix." Proceedings, annual meeting, Electron Microscopy Society of America 45 (August 1987): 150–51. http://dx.doi.org/10.1017/s0424820100125683.
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Potassium-rich aluminates have been observed along the grain boundaries of many commercial aluminas. The presence of alkali aluminates can seriously limit the operation lifetime of sodium vapor lamp tubing by increasing the rate of sodium leakage out of the tube. As part of an investigation into phase and interface structure within the K2O-Al2O3 system, high-purity α-Al2O3, seeded with small granules of potassium carbonate, was studied. In samples which were vacuum hot-pressed within a graphite die at 1400°C for 30min, the potassium (K) doping resulted in the precipitation of a spatially inhomogeneous array of K-rich aluminates. It has since been determined that the precipitation phenomenon was due to insufficient mixing of the starting powders. The potassium carbonate was therefore not originally distributed uniformly within the compacts and locally high K concentrations thus resulted.
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Bribiesca-Vázquez, S., R. Quintana-Puchol, and J. Reyes-Gasga. "Structural and Chemical Analysis of Micro-sized Particles Found in Aluminous Electrical Porcelains." Microscopy and Microanalysis 5, no. 4 (July 1999): 247–53. http://dx.doi.org/10.1017/s1431927699990281.
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Abstract: Uncommon, micro-sized particles with different morphologies were found in sintered aluminous electrical porcelains. The presence of these particles seems to be relatively insensitive to changes in composition of the porcelain system as well as in firing temperatures. X-ray energy-dispersive spectrometry (EDS) microanalysis showed that some particles, those with very well–defined geometries, were composed of K, Si, Al, and O with empirical formula KAlSi2O6—that is, leucite particles. Other particles showed less well–defined geometries, including some composed of Na, Si, Al, and O, corresponding to a sodium aluminum silicate structure, and others of K, Si, Na, Al, and O, corresponding to the leucite composition, where some K has been substituted for Na. The well–defined geometry particles were detected most often, and diffraction analysis with backscattering electrons showed that their unit cell was cubic, with unit cell parameter a = 1.343 nm. The formation of these particles may be the result of the relatively high concentration of K2O and/or Na2O in some very localized zones of the glassy phase due to weak coupling (e.g., alkali-enriched or -depleted melts) during diffusion at a slow cooling rate in the presence of catalytic agents such as TiO2.
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Lee, Dae-Han, Sung-Tae Lee, Ki-Moon Lee, and Sung-Ki Lim. "Analysis of the crystal phases of Na+-beta-aluminas synthesized by infiltration of alkali molten salts." Journal of Industrial and Engineering Chemistry 18, no. 5 (September 2012): 1801–6. http://dx.doi.org/10.1016/j.jiec.2012.04.006.
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Liu, Yu, Pengfei Guan, Bo Zhang, Michael L. Falk, and Howard E. Katz. "Ion Dependence of Gate Dielectric Behavior of Alkali Metal Ion-Incorporated Aluminas in Oxide Field-Effect Transistors." Chemistry of Materials 25, no. 19 (September 18, 2013): 3788–96. http://dx.doi.org/10.1021/cm4012537.
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Stolz, A. J. "Mineralogy of the Nandewar Volcano, northeastern New South Wales, Australia." Mineralogical Magazine 50, no. 356 (June 1986): 241–55. http://dx.doi.org/10.1180/minmag.1986.050.356.07.
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AbstractThe paper discusses the mineralogy of eruptives from the Nandewar Volcano, which range in composition from hawaiite and trachyandesite to comendite via tristanite and mafic and peralkaline trachyte. Olivine, Ca-rich pyroxene, and amphibole display marked decreases in 100 Mg/(Mg + Fe) ratios in the sequence trachyandesite to comendite, reflecting variation in host rock compositions. The presence of tscher-makitic subcalcic pyroxene and aluminous bronzite megacrysts in several trachyandesites indicates that these experienced intratelluric crystallization at elevated pressures (6–8 kbar). Some titanomagnetite and plagioclase phenocrysts in trachyandesites may also be moderate pressure cognate precipitates. Groundmass pyroxenes of some trachytes and comendites are strongly acmitic. The presence or absence of coexisting alkali amphiboles and aenigmatite appears to reflect stability over a relatively broad range of fO2 conditions. Aenigmatite rims on titanomagnetite and ilmenite microphenocrysts in several peralkaline eruptives provides support for a ‘no-oxide’ field in T-fO2 space. The Fe-Ti oxide compositional data indicate that magmas spanning the spectrum trachy-andesite-comendite crystallized under conditions of decreasing T and fO2 which broadly coincided with the FMQ synthetic buffer curve. However, a voluminous group of slightly older associated rhyolites appear to have crystallized under significantly more oxidizing conditions.
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Sutthirat, C., S. Saminpanya, G. T. R. Droop, C. M. B. Henderson, and D. A. C. Manning. "Clinopyroxene-corundum assemblages from alkali basalt and alluvium, eastern Thailand: constraints on the origin of Thai rubies." Mineralogical Magazine 65, no. 2 (April 2001): 277–95. http://dx.doi.org/10.1180/002646101550253.
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AbstractAn inclusion of corundum (ruby) was found in a clinopyroxene xenocryst in alkali basalt from the late-Cenozoic Chanthaburi-Trat volcanics of eastern Thailand. The clinopyroxene is fairly sodic, highly aluminous and magnesian (0.12–0.14 Na, 0.31–0.33 AlIV and 0.36–0.40 AlVI per 6(O), and Mg/(Mg+Fe2+) > 0.9)) and is chemically similar to clinopyroxene inclusions in rubies from nearby alluvial gem deposits, suggesting a common origin for the two types of occurrence. Sapphirine (Mg/(Mg+Fe2+) = 0.91–0.94) and garnet (py56–67alm11–18grs18–23) also occur as inclusions in alluvial rubies. Thermodynamic calculation of the equilibrium 2 di + 2 crn = 2 cats + en constrains the temperatures of clinopyroxene + corundum crystallization to between 800 and 1150 ± 100°C. Use of other equilibria as stability limits places the pressures of crystallization between 10 and 25 kbar, implying depths of between 35 and 88 km. The most Fe-rich clinopyroxene crystallized at a pressure in the lower part of the range. The pyropic garnet inclusions in corundum crystallized at pressures of >18 kbar (i.e. at depths > ~63 km).The xenocrystic clinopyroxene could have coexisted in equilibrium with garnet of similar composition to the observed inclusions at the deduced temperatures of crystallization. The rubies probably crystallized in rocks of mafic composition, i.e. garnet-clinopyroxenites or garnet-pyriclasites, within the upper mantle.
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Gusev, A. I. "PETRO-GEOCHEMISTRY OF SUBVOLCANIC AND EXTRUSIVE FORMATIONS OF THE KEDROVO-KORGONCHIKOVSKY DISTRICT OF THE GORNY ALTAI." Geology and mineral resources of Siberia, no. 3 (October 2022): 45–54. http://dx.doi.org/10.20403/2078-0575-2022-3-45-54.
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The paper provides data on petro-geochemistry, petrology and ore content of subvolcanic and extrusive formations of the Korgon Devonian complex of the Kedrovo-Korgonchikovsky district of the Gorny Altai. Low-alkali rhyodacites, sodium-potassium rhyodacites, trachyrhyodacites, trachyrhyolites and rhyolites are characterized. They are attributed to the aluminous series and mainly to magnesian varieties. Increased gold contents and decreased silver contents are observed in rocks. Ratios of light to heavy lanthanoids show a large range of values – from 2.1 to 26.2 and light ones to medium ones – from 1.94 to 11.8. The tetrad effect of W-type REE fractionation, varying from 0.29 to 0.68 and indicating an abundance of volatile components, including H2O, CO2, S or H2S, was revealed in rocks, that served as the formation of quartzites and argillizites. Volcanites contain signs of mantle formations and contamination by crustal material due to melting of greywackes and amphibolites of the lower crust. The ore content of the district is realized in the formation of promising epithermal gold-silver and copper-molybdenum-gold-porphyry occurrences. The district is thought to be the object of the process manifestation of the fluid mantle-crustal ore genesis during formation of largevolume epithermal gold-silver, copper-molybdenum-gold-porphyry mineralization.
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Sengupta, N., P. Sengupta, and H. K. Sachan. "Aluminous and alkali-deficient tourmaline from the Singhbhum Shear Zone, East Indian shield: Insight for polyphase boron infiltration during regional metamorphism." American Mineralogist 96, no. 5-6 (May 1, 2011): 752–67. http://dx.doi.org/10.2138/am.2011.3560.
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UPTON, B. G. J., A. C. SKOVGAARD, J. McCLURG, L. KIRSTEIN, M. CHEADLE, C. H. EMELEUS, W. J. WADSWORTH, and A. E. FALLICK. "Picritic magmas and the Rum ultramafic complex, Scotland." Geological Magazine 139, no. 4 (July 2002): 437–52. http://dx.doi.org/10.1017/s0016756802006684.
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Three small picritic dykes, intruded at a late stage in the evolution of the Rum basic–ultra-basic complex, Inner Hebrides, shed new light on the nature of the magmas responsible for the main complex. The magmas are of transitional (mildly alkalic) type, generated by relatively small-fraction (6–7%) melting of a depleted mantle source. Melting is tentatively deduced to have commenced at ±100 km, straddling the garnet–spinel transition. Of the three samples, one (M9) is remarkable for the preservation of very primitive characteristics, with olivines of Fo93 containing highly aluminous spinels; these appear unique within the British Tertiary Volcanic Province. Sr, Nd and Pb isotopes indicate only minor ([les ]4%) contamination with Precambrian crustal lithologies, reflecting the rapidity of ascent of the magma batches. The Rum picrites have 187Os/188Os ratios and trace element characteristics comparable to those of recent picrites from Iceland, suggesting minimal temporal change of the depleted parts of the Iceland plume over 60 Ma. Movements of the Long Loch Fault may have been instrumental in causing decompression melting of the spreading Iceland plume-head and facilitating ascent of the melts to near-surface levels.
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Patel, N. "An acoustic study of the mixed-alkali-mixed phase β-aluminas. Part 1: Naβ″/β_Al2O3, Kβ″/β_Al2O3 and (Na0.6K0.4)β″/β_Al2O3." Solid State Ionics 22, no. 4 (February 1987): 305–12. http://dx.doi.org/10.1016/0167-2738(87)90148-2.
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Aydar, E., A. Gourgaud, C. Deniel, N. Lyberis, and N. Gundogdu. "Le volcanisme quaternaire d'Anatolie centrale (Turquie): association de magmatismes calco-alcalin et alcalin en domaine de convergence." Canadian Journal of Earth Sciences 32, no. 7 (July 1, 1995): 1058–69. http://dx.doi.org/10.1139/e95-087.
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Collision volcanism in Central Anatolia (Cappadocia) began at least in the late Miocene. Because of the North–South Arabian-Eurasian convergence since this period, the Anatolian block is displaced towards the West along the North and East Anatolian strike-slip faults. Kinematic reconstructions show that the East Anatolian Fault is both sinistral and convergent. As a consequence, the Anatolian block is currently being deformed. Quaternary volcanism in Central Anatolia is represented by several hundreds of monogenetic scoria cones, lava flows, maars, and domes as well as two strato-volcanoes, Hasan Dag and Erciyes Dag. The monogenetic volcanism is bimodal (basalts and rhyolites), whereas the stratovolcanoes exhibit a complete calc-alkaline suite, from basalts to rhyolites. Most of the igneous products are calc-alkaline. Basalts erupted mainly from the monogenetic cones, lava flows, and maars. Andesites are encountered in the strato-volcanoes as lava flows, domes, and nuees ardentes deposits. Dacites and rhyolites occur as ignimbrites and dispersed maars and domes. Volcanic events were recorded up to historical times. Some basalts from monogenetic edifices, contemporaneous with the calc-alkaline suite, exhibit mineralogical and geochemical features that are typical of intraplate alkaline suites, such as normative nepheline, alkali feldspars, and Ti and Cr-rich Cpx. Euhedral microlites of aluminous garnet, although rare, have been observed in basalts, rhyodacites, and rhyolites. This association of contemporaneous calc-alkaline and alkaline suites may be related to collision tectonics.
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Victor Owen, J. "Geochemistry of orbicular diorite from the Grenville Front zone, eastern Labrador." Mineralogical Magazine 56, no. 385 (December 1992): 451–58. http://dx.doi.org/10.1180/minmag.1992.056.385.01.
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AbstractOrbicules in diorite from the Grenville Front zone of eastern Labrador consist of biotite- and/or hornblende-studded, dioritic cores enclosed by fine-grained shell structures alternately enriched and depleted in biotite. The orbicules occur in a mesocratic, quartz-bearing matrix. Epidote of inferred magmatic origin occurs in all parts of the rock. Plagioclase in the matrix is relatively sodic, and biotite more ferroan than in the orbicules, suggesting that the matrix material has the most evolved composition, and crystallized last.The diorite is unusually aluminous (orbicules: 24.9-27.4 wt.% Al2O3; matrix: 22.4-23.6% Al2O3) and calcic (orbicules: 7.0-8.4 wt.% CaO; matrix: 6.0-6.9% CaO); it shows a positive Eu anomaly, and has elevated Sr concentrations (1800-2500 ppm Sr), demonstrating that, compositionally, it resembles a plagioclase cumulate. Mass-balance calculations suggest that the orbicule cores had a crystal/melt ratio of ≤5. This accounts for the extreme fractionation of the rock (e.g., in orbicules, Zr <5 ppm). Compared with fractional crystallization patterns, variation diagrams show counter-trends (e.g. the siliceous matrix contains elevated TiO2) or scatter for several components, suggesting that the crystal/melt ratio governed some of the geochemical characteristics of the diorite.The presence of coarse mafic clots containing primary epidote, biotite and/or hornblende testify to an elevated water content in the orbieule cores. The shell magma apparently formed as a result of the interaction of supercooled orbicule core fluids with the matrix magma, and tended to serve as a reservoir for alkalis and Fe. Alkalis and Ca diffused in opposite directions, possibly as a result of a temperature gradient at the orbicule/matrix interface. This, however, requires decoupling of the thermodiffusional behaviour of alkalis and femic components in hydrated intermediate magma, which contrasts with documented Soret diffusion in mafic systems.The solidification of the shell magma prior, to the orbicule cores and matrix is attributed to dewatering, consistent with the fine grain size of the shell structures. Except where remobilized core material has disrupted the shells, the cores crystallized in isolation from the matrix, which fractionated toward a more evolved composition.
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Raeside, Robert P., and Sandra M. Barr. "Geology and tectonic development of the Bras d'Or suspect terrane, Cape Breton Island, Nova Scotia." Canadian Journal of Earth Sciences 27, no. 10 (October 1, 1990): 1371–81. http://dx.doi.org/10.1139/e90-147.
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The Bras d'Or Terrane is defined in Cape Breton Island and consists of four distinctive components, (i) Low-pressure, regionally metamorphosed aluminous and calcareous gneiss of the Proterozoic Bras d'Or metamorphic suite is restricted to the southeastern part of the terrane. (ii) Late Proterozoic clastic-volcanic-carbonate units (Blues Brook, Malagawatch, McMillan Flowage, and Benacadie Brook formations, and Barachois River and Bateman Brook metamorphic suites) occur throughout the terrane and are generally at low metamorphic grades, although sillimanite grade has locally been achieved, (iii) A suite of 555–565 Ma calc-alkalic dioritic to granitic plutons was emplaced at pressures ranging from about 900 to less than 100 MPa. (iv) Early Ordovician granitic plutonism and Ordovician 40Ar/39Ar ages record regional heating.The Bras d'Or Terrane docked with the Mira Terrane to the southeast no earlier than the Ordovician. Cambro-Ordovician sedimentary rocks of the Mira Terrane appear locally to be thrust over the Bras d'Or Terrane. Mississippian sedimentary rocks overlap both terranes. The present boundary, the Macintosh Brook Fault, is mainly a Carboniferous feature. Docking with the Aspy Terrane to the northwest occurred along the Eastern Highlands shear zone and is constrained by a 375 Ma stitching pluton, the Black Brook Granitic Suite. Docking may have been initiated as early as 415 Ma, as indicated by reset 40Ar/39Ar ages near the boundary. The three Proterozoic components of the Bras d'Or Terrane have been recognized in the Brookville Terrane of southern New Brunswick, and Late Proterozoic gneiss, Late Proterozoic – early Cambrian calc-alkalic plutons and Ordovician granitic plutons have been reported in parts of the Hermitage Flexure of southern Newfoundland. The Bras d'Or Terrane may therefore be a regionally significant component of the northern Appalachian Orogen.
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Pokhilenko, Lyudmila. "Kelyphite Rims on Garnets of Contrast Parageneses in Mantle Xenoliths from the Udachnaya-East Kimberlite Pipe (Yakutia)." Minerals 11, no. 6 (June 8, 2021): 615. http://dx.doi.org/10.3390/min11060615.
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A new classification of kelyphitic rims on garnets from xenoliths of peridotitic and eclogitic parageneses of the mantle section under the Udachnaya-East kimberlite pipe (Yakutia) is presented. Five types of rims are identified: Rim1 develops between garnet and olivine/pyroxene (or rim2) and is composed of high-alumina pyroxenes, spinel, phlogopite; rim2, the coarse grain part of rim1, is located between rim1 and olivine/pyroxene, and mainly consists of phlogopite and less aluminous larger pyroxenes and spinel; rim3 develops between garnet and kimberlite, and presents with phlogopite and Fe-Ti spinel; rim4 sometimes presents instead of rim1/rim2 and consists of zoned high-Cr phlogopite with rare fine grains of chromium spinel; rim5, a “pocket” between garnet and rim1, is represented by microcrystalline aggregates of clinopyroxene, mica, spinel, calcite, and feldspar in different variations. Rims 1, 2, and 3 are typical for garnets of all studied parageneses. Rims 4 and 5 develop on high-Cr subcalcic garnets of the most depleted peridotites. Reactions of the formation of all types of rims are given in the article. Each type of kelyphite demonstrates a clear enrichment with a certain component: Rim1—MgO and alkalis; rim2—TiO2; rim3—FeO and TiO2; rim4—Cr2O3; and rim5—CaO, suggesting the multistage injection of different components by mantle fluid.
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Chartier, D., B. Muzeau, L. Stefan, J. Sanchez-Canet, and C. Monguillon. "Magnesium alloys and graphite wastes encapsulated in cementitious materials: reduction of galvanic corrosion using alkali hydroxide activated blast furnace slag." MRS Advances 1, no. 62 (2016): 4095–101. http://dx.doi.org/10.1557/adv.2017.195.
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ABSTRACTMagnesium alloys (Mg-0.5%Zr and Mg-1.2%Mn) and graphite from spent nuclear fuel that has been used in the former French gas cooled reactors, have been stored together in AREVA La Hague plant. The recovery and packaging of these wastes is currently studied and several solutions are under consideration. One of the developed solutions would be to mix these wastes in a grout composed of industrially available cement, e.g. OPC, OPC blended with blast furnace slag or aluminous cement. Within the alkaline pore solution of these matrixes, magnesium alloys are imperfectly protected by a layer of magnesium hydroxide (Mg(OH)2, Brucite) resulting in a slow process of corrosion releasing hydrogen. As the production of this gas must be considered for the storage safety, and the quality of wasteform, it is important to select a cement matrix capable of lowering the corrosion kinetics of magnesium alloys. This is especially true when magnesium alloys are conditioned together with graphite wastes. Indeed, galvanic coupling phenomena may increase early age corrosion of the mixed wastes, as magnesium and graphite will be found in electrical contact in the same electrolyte. Many types of cements have been tested and most of them have caused strong hydrogen production when magnesium alloys and graphite are conditioned together into such cement pastes. Exceptions are geopolymer binder which is already known for that and another binder based on alkali hydroxide activated ground granulated blast furnace slag (AHABFS) which is presented in the present article. First are presented hydrogen production experiments that demonstrate the efficiency of AHABFS towards reduction of corrosion of Mg alloys embedded. In a second part, a formulation of fluid mortar based on this binder is proposed.
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Li, Yang, Yang Yang, Yi-Can Liu, Chiara Groppo, and Franco Rolfo. "Muscovite Dehydration Melting in Silica-Undersaturated Systems: A Case Study from Corundum-Bearing Anatectic Rocks in the Dabie Orogen." Minerals 10, no. 3 (February 27, 2020): 213. http://dx.doi.org/10.3390/min10030213.
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Corundum-bearing anatectic aluminous rocks are exposed in the deeply subducted North Dabie complex zone (NDZ), of Central China. The rocks consist of corundum, biotite, K-feldspar and plagioclase, and show clear macro- and micro-structural evidence of anatexis by dehydration melting of muscovite in the absence of quartz. Mineral textures and chemical data integrated with phase equilibria modeling, indicate that coarse-grained corundum in leucosome domains is a peritectic phase, reflecting dehydration melting of muscovite through the reaction: Muscovite = Corundum + K-feldspar + Melt. Aggregates of fine-grained, oriented, corundum grains intergrown with alkali feldspar in the mesosome domains are, instead, formed by the dehydration melting of muscovite with aluminosilicate, through the reaction: Muscovite + Al-silicate = Corundum + K-feldspar + Melt. P-T pseudosections modeling in the Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2 system constrains peak pressure-temperature (P-T) conditions at 900–950 °C, 9–14 kbar. The formation of peritectic corundum in the studied rocks is a robust petrographic evidence of white mica decompression melting that has occurred during the near-isothermal exhumation of the NDZ. Combined with P-T estimates for the other metamorphic rocks in the area, these new results further confirm that the NDZ experienced a long-lived high-T evolution with a near-isothermal decompression path from mantle depths to lower-crustal levels. Furthermore, our new data suggest that white mica decompression melting during exhumation of the NDZ was a long-lasting process occurring on a depth interval of more than 30 km.
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Wang, Zeng-Zhen, Xuan-Hua Chen, Zhao-Gang Shao, Bing Li, Hong-Xu Chen, Wei-Cui Ding, Yao-Yao Zhang, and Yong-Chao Wang. "Geochronology, geochemistry and tectonic implications of early Carboniferous plutons in the southwestern Alxa Block." Geological Magazine 159, no. 3 (November 12, 2021): 372–88. http://dx.doi.org/10.1017/s0016756821000984.
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AbstractThe southeastern Central Asian Orogenic Belt (CAOB) records the assembly process between several micro-continental blocks and the North China Craton (NCC), with the consumption of the Paleo-Asian Ocean (PAO), but whether the S-wards subduction of the PAO beneath the northern NCC was ongoing during Carboniferous–Permian time is still being debated. A key issue to resolve this controversy is whether the Carboniferous magmatism in the northern NCC was continental arc magmatism. The Alxa Block is the western segment of the northern NCC and contiguous to the southeastern CAOB, and their Carboniferous–Permian magmatism could have occurred in similar tectonic settings. In this contribution, new zircon U–Pb ages, elemental geochemistry and Sr–Nd isotopic analyses are presented for three early Carboniferous granitic plutons in the southwestern Alxa Block. Two newly identified aluminous A-type granites, an alkali-feldspar granite (331.6 ± 1.6 Ma) and a monzogranite (331.8 ± 1.7 Ma), exhibit juvenile and radiogenic Sr–Nd isotopic features, respectively. Although a granodiorite (326.2 ± 6.6 Ma) is characterized by high Sr/Y ratios (97.4–139.9), which is generally treated as an adikitic feature, this sample has highly radiogenic Sr–Nd isotopes and displays significantly higher K2O/Na2O ratios than typical adakites. These three granites were probably derived from the partial melting of Precambrian continental crustal sources heated by upwelling asthenosphere in lithospheric extensional setting. Regionally, both the Alxa Block and the southeastern CAOB are characterized by the formation of early Carboniferous extension-related magmatic rocks but lack coeval sedimentary deposits, suggesting a uniform lithospheric extensional setting rather than a simple continental arc.
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Thomas, C. W., and P. H. Nixon. "Lower crustal granulite xenoliths in carbonatite volcanoes of the Western Rift of East Africa." Mineralogical Magazine 51, no. 363 (December 1987): 621–33. http://dx.doi.org/10.1180/minmag.1987.051.363.01.
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AbstractSporadic small garnet granulite and two-pyroxene granulite xenoliths found in the carbonatite tuffs and lavas near Fort Portal, South West Uganda, are chiefly silica-saturated and rich in Al2O3 (> 20 wt. %) and Na2O (c. 2 to 4 wt. %). Three REE patterns are distinguished: LREE enriched—HREE depleted with a positive Eu anomaly; LREE depleted—HREE relatively enriched and flat; and LREE slightly enriched with a very weak Eu anomaly and high overall REE. The xenoliths are considered to represent original basaltic melts and fractional crystallisation products, varying with the dominance of the clinopyroxene, plagioclase or olivine crystallising phase. It is thought that REE abundances were established before metamorphism.The clinopyroxenes are low-jadeitic augites, the orthopyroxenes, aluminous hypersthenes and the garnets, pyrope-almandine with constant grossularite. Plagioclase varies with increasing metamorphic grade from labradorite to andesine-oligoclase. Scapolite (meionite), alkali-feldspar, quartz, mica, amphibole, rutile and apatite are minor phases and some appear to be metasomatic.Calculated temperatures of metamorphic equilibration range from 580 to 800°C at pressures > 4 kbar for the two-pyroxene granulites and > 6 kbar for the garnet granulites. A known geophysical discontinuity marking a density change at 16 km in the Western Rift may be due to the presence of two-pyroxene granulite, calculated to become garnet-bearing at depths greater than 23 km. The absence of proven omphacite-bearing eclogite xenoliths (with no plagioclase) indicates that the greatest depth of crustal sampling by the carbonatite in the Fort Portal field is about 25 km which could be the depth of the Moho in this area.
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Souza, Márcio Roberto Wilbert de, Rommulo Vieira Conceição, Daniel Grings Cedeño, and Roberto Vicente Schmitz Quinteiro. "Study of silica-undersaturated magmas through the Kalsilite- Nepheline-Diopside-Silica system at 4.0 GPa and dry conditions." Geologia USP. Série Científica 18, no. 2 (July 24, 2018): 87–102. http://dx.doi.org/10.11606/issn.2316-9095.v18-126120.
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This study experimentally investigates the Kalsilite-Nepheline-Diopside-Silica system at high pressure and temperature, with emphasis on silica-undersaturated volume (leucite-nepheline-diopside — Lct-Nph-Di; and kalsilite-nepheline-diopside — Kls + Nph + Di — planes), at 4.0 GPa (~120 km deep), temperatures up to 1,400ºC and dry conditions, to better understand the influence of K2O, Na2O, and CaO in alkali-rich silica-undersaturated magma genesis. In the Lct-Nph-Di plane, we determined the stability fields for kalsilite (Klsss), nepheline (Nphss) and clinopyroxene (Cpxss) solid solutions, wollastonite (Wo) and sanidine (Sa); and three piercing points: (i) pseudo-eutectic Kls + Nph + Di + liquid (Lct62Nph29Di9) at 1,000ºC; (ii) Kls + Sa + (Di + Wo) + liquid (Lct75Nph22Di2) at 1,200ºC; and (iii) pseudo-eutectic Kls + Di + Wo + liquid (Lct74Nph17Di9) at 1,000ºC. Kalsilite stability field represents a thermal barrier between ultrapotassic/potassic vs. sodic compositions. In the plane Kls-Nph-Di, we determined the stability fields for Klsss, Nphss and Cpxss and two aluminous phases in smaller proportions: spinel (Spl) and corundum (Crn). This plane has a piercing point in Kls + Nph + Di(± Spl) + liquid (Kls47Nph43Di10) at 1,100ºC. Our data showed that pressure extends K dissolution in Nph (up to 39 mol%) and Na in Kls (up to 27 mol%), and that these solid solutions, if present, determinate how much enriched in K and Na an alkaline magma will be in an alkaline-enriched metasomatic mantle. Additionally, we noted positive correlation between K2O and SiO2 concentration in experimental melts, negative correlation between CaO and SiO2, and no evident correlation between Na2O and SiO2.
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Stevens, J. R., and W. Wieczorek. "Ionically conducting polyether composites." Canadian Journal of Chemistry 74, no. 11 (November 1, 1996): 2106–13. http://dx.doi.org/10.1139/v96-239.
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Ionic conductivity in polymer–salt electrolytes occurs in the amorphous regions of the complex. Poly(ethylene oxide) (PEO) is the best polyether for complexing salts. Unfortunately, it is partially crystalline at ambient temperatures. With inorganic (i.e., alumina) or organic (i.e., poly(acrylamide) (PAAM)) fillers the crystallization of PEO is inhibited and the room temperature conductivity is enhanced in these mixed phase systems by over two orders of magnitude (to ~ 10−4 S/cm) above the base PEO–salt system (<10− S/cm). Even adding PAAM to an initially amorphous system (oxymethylene-linked PEO–LiClO4) increases the room temperature conductivity by 2 to 3 times. Various alkali metal salts (Li, Na) and NH4SCN are used with α-Al2O3, θ-Al2O3, PAAM′ and poly(N,N′-dimethyl acrylamide) as fillers. The aluminas stiffen the complex and increase Tg. The addition of the organic fillers lowers Tg, as is to be preferred. It is suggested that changes in the conductivity with changes in salt and filler concentration are due to changes in the ultrastructure and morphology and are the result of an equilibrium between various Lewis acid – Lewis base reactions. Qualified success has been achieved in modelling ionic conductivity in these composite electrolyte systems using an effective medium approach. In this approach it has been assumed that the main conductivity enhancement takes place in thin amorphous layers of the polyether that coat the dispersed polyacrylamide particles separated in a microphase. In the best complexes this layer is identified by a second Tg. Key words: polyethers, composites, ionic conductivity, phase structure, Lewis acids and bases.
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Perevoznikova, E. V., and V. T. Kazachenko. "Mineralogy of spessartine-quartz rocks of the Sikhote-Alin." LITHOSPHERE (Russia) 21, no. 1 (March 4, 2021): 70–89. http://dx.doi.org/10.24930/1681-9004-2021-21-1-70-89.
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Research subject. The article is devoted to the study of spessartine-quartz rocks of the Triassic chert formation of the Sikhote-Alin. The research objects involved the outcrops of spessartine-quartz rocks of the Gornaya and Shirokaya Pad areas from Malinovka and Olga ore districts (in the Samarka and Taukha terranes respectively). Materials and methods. The selection of stone materials was performed manually. The diagnostic of minerals was performed using the microscope in transmitted and reflected light and carried out by the determination of their composion. The polished sections of the minerals were investigated at the FEGI FEB RAS using JXA8100 microanalysers. Results. Spessartine-quartz and manganese silicate rocks occupy the same position in the section of the Triassic deposits of the Taukha and Samarka terrains. This indicates a synchronous accumulation of sediments (protoliths of these rocks) in a single sedimentary basin. The rocks formed by contact metamorphism in the Late and Early Cretaceous large granitoid massifs. This process is manifested in the presence of a variety of such minerals, as spessartine, members of the ilmenite-pyrophanite series, titanite, monazite, bastnesite, allanite, apatite, zircon, baddeleyite, torianite and others. The rocks under study also include such rare minerals, as cheralite, greyite and a rare variety of fluorine-aluminous titanite. Conclusion. The occurrence (during contact metamorphism of siliceous-rhodochrosite rocks) of spessartine-quartz or manganesesilicate rocks composed mainly of pyroxenoids, was determined by both the relative amounts of carbonate and clay matter, as well as the concentrations of Ba and alkalis in the initial sediments.
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Xia, Fang, Shunda Li, Lingling Gao, and Chuan Chen. "Geochemistry, Zircon U–Pb Ages, and Hf Isotopes of the Devonian Mafic and Acidic Dykes of the Jinba Gold Deposit, NW China: Petrogenesis and Tectonic Implications." Minerals 12, no. 7 (July 9, 2022): 871. http://dx.doi.org/10.3390/min12070871.
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The Jinba deposit is an orogenic gold deposit located in the Markakuli shear zone, in the southern part of the Altay orogenic belt, northwestern China. Several granite and diorite dykes are present in the area of the mine, with ore bodies occurring in the diorite dykes. However, the diagenetic age, genesis, and evolution of these magmas, and the tectonic setting of the dyke emplacement process, remain unclear. The present study is based on a detailed geological survey, zircon U–Pb dating, Lu–Hf isotopes, and geochemical analysis of the granitic and diorite dykes. The crystallization ages of the granitic and diorite dykes are 384.5 ± 1.2 Ma and 393.9 ± 3.5 Ma, respectively, which indicates formation in the Early to Middle Devonian. Zircon εHf(t) values of the granitic and diorite dykes are 1.43 to 5.2 and −4.47 to −1.18, respectively, with a corresponding two-stage model of depleted mantle (TDM2) ages of 1046 to 1285 Ma and 1242 to 2623 Ma, respectively. This indicates that the granitic and diorite dykes were formed by the mixing of mantle magma and crustal materials to varying degrees, and diorite dykes are more obviously contaminated by the lower crust. Geochemical analysis shows that the granite dykes have a high SiO2 (72.51%–74.87%) and moderate Al2O3 (12.88%–14.04%) content, a total alkali of (K2O + Na2O = 5.51%–6.44%), and aluminous (A/CNK = 1.0–1.02). Granite dykes are enriched in LREE and Th, U, and Pb, and depleted in P, Sr, and Nb elements, with clear Eu negative anomalies (δEu = 0.62~0.66). The SiO2 content of diorite dykes is 51.48%–53.71%, Al2O3 contents are high (14.70%–15.99%), K2O is 1.94%–2.54%, Na2O is 2.97%–3.96%, MgO contents are high (5.15%–6.46%), and TFe2O3 is (13.42%–15.13%), enriched Sr, U, Pb, deficient Th elements, rare earth fractionation is not obvious, and Eu anomaly is not obvious (δEu = 0.93~1.1). We conclude that the Early to Middle Devonian magmatism in the southern margin of Altay (which corresponds to the Jinba gold deposit) may have formed in an island arc-related subduction environment.
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Alelweet, Omar, Sara Pavia, and Zehao Lei. "Pozzolanic and Cementing Activity of Raw and Pyro-Processed Saudi Arabian Red Mud (RM) Waste." Recent Progress in Materials 3, no. 4 (September 28, 2021): 1. http://dx.doi.org/10.21926/rpm.2104047.
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This paper investigates the composition, properties and reactivity of a red mud waste generated in Saudi Arabia with a view to find alternative materials to replace construction binders of high environmental impact. The phase transformation triggered by the sintering of the RM up to 1000°C is determined with thermal and X-Ray Diffraction analyses. Reactivity is investigated with chemical and physical methods including the Chapelle test, setting times, mechanical index and microscopy. The RM is clearly pozzolanic, and its activity is mainly due to the reaction of feldespathoids and the formation of zeolitic and feldspathoid-based hydrates. The positive effects of the thermal treatment are seen below 750°C, and include the loss of water in the zeolite/feldespathoids, and the destruction of the crystal structures of the clay minerals inherited form the parent bauxite. The negative effects of the thermal treatment are evidenced over 750°C, with a decrease in specific surface area, devitrification and crystal formation, whereby the active transition aluminas and the fedespathoids/zeolites (mainly cancrinite) transform into nepheline, tricalcium aluminate (C3A) and gehlenite. Despite the occurrence of nepheline, C3A and gehlenite in the RM sintered at 1000°C, the formation of pozzolanic hydrates that cause setting and strength development are greater at lower temperature. The optimum thermal treatment that enhances pozzolanic activity lies at c.400°C, as evidenced by the highest lime combination, the greatest mechanical index and the fastest set. The RM consists of gibbsite and boehmite, inherited from the bauxite, and cancrinite, chantalite and sodalite formed during the Bayer process. Feldespathoids have formed, instead of zeolites, due to the available silica and the high alkali content of the RM. The quick lime -CaO -, added twice during the refining process, has transformed the original goethite into hematite, and produced cancrinite. The Saudi RM has high SiO2 and high alkalinity, and an abundant specific surface area available for reaction. The chloride and carbon contents are low, and no environmental toxicity is inferred from its chemistry.
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Goma Ginesta, Ferrán. "Análisis de los factores que tienen influencia en la disminución de resistencias residuales por disolución alcalina en los morteros intersticiales de hormigones con cemento aluminoso. Evaluación de los límites de riesgo en el caso de los techos." Materiales de Construcción 45, no. 238 (June 30, 1995): 19–34. http://dx.doi.org/10.3989/mc.1995.v45.i238.558.
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Young, Davis. "Origin of the American Quantitative Igneous Rock Classification: Part 4." Earth Sciences History 30, no. 1 (December 1, 2011): 1–38. http://dx.doi.org/10.17704/eshi.30.1.65q0ng14n572846u.
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After several failed attempts to construct a new chemico-mineralogical igneous rock classification on the basis of three or more factors, C. Whitman Cross, Joseph P. Iddings, Louis V. Pirsson, and Henry S. Washington decided to establish a practical and logically consistent scheme on the basis of only two factors, namely, two primary groups consisting of hypothetical minerals with ideal chemical compositions, the amounts of which were to be calculated from the chemical compositions of igneous rocks. One primary group consisted mainly of alkali alumina silicates and quartz (salic minerals), whereas the other consisted mainly of calcic ferromagnesian minerals (femic). A list of the amounts of these calculated standard minerals within an igneous rock was termed the norm, and the list of the proportions of actual minerals in a rock was termed its mode.In the Fall of 1901 the quartet decided to publish a preliminary paper that presented the major themes of their two-factor classification scheme. Iddings was charged with writing a draft of the scheme, and Washington was assigned the task of producing an essay on nomenclature to be published later. The team continually refined the definitions of specific subdivisions of the scheme proposed by Iddings as well as the corresponding nomenclature proposed by Washington. They also refined the norm calculation algorithm and developed methods for calculating the norm from the mode of rocks containing aluminous ferromagnesian minerals such as hornblende and biotite.After a few months of evaluating and revising a succession of drafts, the team eventually determined to publish their work of classification and nomenclature all at once by combining the refined drafts into one large comprehensive manuscript in three parts: Part I on classification, Part II on nomenclature, and Part III on methods of calculation. Iddings coordinated and edited the various criticisms and drafts contributed by team members into one large manuscript and shepherded the project to final publication in late October 1902 in Journal of Geology. The massive 139-page article entitled ‘A quantitative chemico-mineralogical classification and nomenclature of igneous rocks’ was preceded in earlier issues of the same journal by a two-part series authored by Cross on the historical development of systematic petrography. In early 1903, both of Cross's papers and the CIPW article were combined and published as a book, Quantitative Classification of Igneous Rocks.
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Redin, Yury O., Anna A. Redina, Viktor P. Mokrushnikov, Alexandra V. Malyutina, and Vladislav F. Dultsev. "The Kultuma Au–Cu–Fe-Skarn Deposit (Eastern Transbaikalia): Magmatism, Zircon Geochemistry, Mineralogy, Age, Formation Conditions and Isotope Geochemical Data." Minerals 12, no. 1 (December 22, 2021): 12. http://dx.doi.org/10.3390/min12010012.
Full textAbstract:
The Kultuma deposit is among the largest and most representative Au–Cu–Fe–skarn deposits situated in Eastern Transbaikalia. However, its genetic classification is still a controversial issue. The deposit is confined to the similarly named massif of the Shakhtama complex, which is composed mainly of quartz monzodiorite-porphyry and second-phase monzodiorite-porphyry. The magmatic rocks are characterized by a low Fe2O3/FeO ratio, low magnetic susceptibility and belong to meta-aluminous, magnesian high-potassic calc-alkalic reduced granitoids of type I. The results of 40Ar-39Ar and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating showed that the formation of magmatic rocks proceeded during the Late Jurassic time: 161.5–156.8 Ma. Relatively low Ce/Ce*, Eu/Eu* and Dy/Yb ratios in the zircons indicate that the studied magmatic rocks were formed under relatively reduced conditions and initially contained a rather low amount of magmatic water. A mineralogical–geochemical investigation allowed us to outline five main stages (prograde skarn, retrograde skarn, potassic alteration, propylitic (hydrosilicate) alteration and late low-temperature alteration) of mineral formation, each of them being characterized by a definite paragenetic mineral association. The major iron, gold and copper ores were formed at the stage of retrograde skarn and potassic alteration, while the formation of polymetallic ores proceeded at the stage of propylitic alteration. The obtained timing of the formation of retrograde skarn (156.3 Ma) and magmatic rocks of the Shakhtama complex, along with the direct geological observations, suggest their spatial–temporal and genetic relationship. The data obtained on the age of magmatic rocks and ore mineralization are interpreted as indicating the formation of the Kultuma deposit that proceeded at the final stages of collision. Results of the investigation of the isotope composition of S in sulfide minerals point to their substantial enrichment with the heavy sulfur isotope (δ34S from 6.6 to 16‰). The only exclusion with anomalous low δ34S values (from 1.4 to 3.7‰) is pyrrhotite from retrograde skarns of the Ochunogda region. These differences are, first of all, due to the composition of the host rocks. Results of the studies of C and O isotope composition allow us to conclude that one of the main sources of carbon was the host rocks of the Bystrinskaya formation, while the changes in the isotope composition of oxygen are mainly connected with decarbonization processes and the interactions of magmatic fluids, host rocks and meteoric waters. The fluids that are responsible for the formation of the mineral associations of retrograde skarns and the zones of potassic alteration at the Kultuma deposit were reduced, moderately hot (~360–440 °C) and high-pressure (estimated pressure is up to 2.4 kbar). The distinguishing features of the fluids in the zones of potassic alteration at the Ochunogda region are a lower concentration and lower estimated pressure values (~1.7 kbar). The propylitic alteration took place with the participation of reduced lower-temperature (~280–320 °C) and lower-pressure (1–1.2 kbar) fluids saturated with carbon dioxide, which were later on diluted with meteoric waters to become more water-rich and low-temperature (~245–260 °C). The studies showed that the main factors that affected the distribution and specificity of mineralization are magmatic, lithological and structural–tectonic ones. Results of the studies allow us to classify the Kultuma deposit as a Au–Cu–Fe–skarn deposit related to reduced intrusion.
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Grams, Samuel, Jonathan Mai, Jens Langer, and Sjoerd Harder. "Alkali metal influences in aluminyl complexes." Dalton Transactions, 2022. http://dx.doi.org/10.1039/d2dt02111k.
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Ballmann, Gerd M., Matthew J. Evans, Thomas X. Gentner, Alan R. Kennedy, J. Robin Fulton, Martyn P. Coles, and Robert E. Mulvey. "Synthesis, Characterization, and Structural Analysis of AM[Al(NONDipp)(H)(SiH2Ph)] (AM = Li, Na, K, Rb, Cs) Compounds, Made Via Oxidative Addition of Phenylsilane to Alkali Metal Aluminyls." Inorganic Chemistry, November 23, 2022. http://dx.doi.org/10.1021/acs.inorgchem.2c03010.
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Petrakova, Marina E., Roman A. Terentiev, Anastasia V. Yurchenko, and Konstantin A. Savko. "Geochemistry and geochronology of quartz monzogabbro – monzodiorite – granodiorites of the Potudan pluton (Volga-Don orogen)." Vestnik of Saint Petersburg University. Earth Sciences 67, no. 1 (2022). http://dx.doi.org/10.21638/spbu07.2022.105.
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This article presents new and summaries of previously published geochemical and geochronological data on rocks of the Potudan pluton and host granitoids of the Kholhol-Repyevka batholith in the central part of the Don Terrane (DT) of Volga-Don orogen. The host granitoids of the Khokhol-Repyevka batholith are assigned to the Pavlovsk granitoid complex, which is widespread in the southern part of the DT. The studied Potudan pluton rocks are differentiated from quartz monzogabbro to granodiorites. They are ferroan, meta-aluminous, and the K2O content displays their relationship to the shoshonite series. For the intrusive complexes of the Don terrane, it is assumed that an enriched heterogeneous source with high contents of alkalis, LILE (large-scale lithophile elements) and LREE (light rare earth elements) is involved, the mantle component is confirmed by increased of MgO, Cr, Ni, Ti, as well as high Sr/Y ratios, (La/Yb)n, (Dy/Yb)n, indicating the deep origin of magmas. The source heterogeneity could have been provided by subduction events about 2.1 Ga. The U-Pb zircon age of crystallization of the Potudan pluton rocks (using the SHRIMP II instrument) is 2061 ± 5.4 Ma and corresponds to the postcollision event in the junction zone of the Sarmatian and Volga-Ural segments of the East European Craton. Association of Potudan rocks with Pavlovsk granitoids in time and space and also morphological features of zircon from various types of rock suites prove the effect of hybridization process during crystallization of the composite batholith. The new data make it possible to expand our understanding of the evolution of crust of the Don Terrane and geodynamic regims of its formation.
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Bilal, Essaïd. "GEOCHIMIE ET CONDITIONS DE CRISTALLISATION DES MINERAUX DU GROUPE DE L’HELVITE." Geonomos, December 1, 1994. http://dx.doi.org/10.18285/geonomos.v2i2.221.
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Minerais de berílio (berilo, fenaquita e helvita) são constituintes de veios a quartzo-muscovita e veios de siderofilita. Noalbitito, somente a fenaquita e a helvita estão presentes. Este trabalho refere-se à ocorrência do maciço de Sucuri (Goiás, Brasil),às helvitas dos skarns de Costabonne, França e às helvitas de veios a quartzo-wolframita de Dajishan, China.O estudo paragenético, geoquímico e experimental de helvitas (Mn, Zn, Fe)8 Be6 Si6 O24 S2 analisadas leva à uma novadefinição da fórmula estrutural deste mineral que, por analogia àquela da hauyna é (Mn, Zn, Fe)8-x Nax Be6 Si6 O24 S2-x Clx. Àssubstituições clássicas Zn-Fe-Mn, se ajuntam as substituições do tipo: Cl-S e Be-Li. O Li substitui o Be na estrutura da helvita, odéficit de carga elétrica resultante é compensado pela introdução de Na na estrutura. A substituição Cl-S foi confirmada porestudo experimental. Restrições de ordem geoquímica desempenham um importante papel na introdução de terras raras na estruturada helvita, de modo que num ambiente francamente alcalino, a helvita concentra mais facilmente as terras raras pesadas.A danalita (pólo ferrífero da helvita) cristaliza-se em um domínio de fugacidade do enxofre e do oxigênio muito limitado eque corresponde ao domínio de estabilidade da pirrotita. A genthelvita (pólo zincífero da helvita) é estável em um extensodomínio de fugacidade do enxofre e oxigênio. Ao contrário, a helvita (pólo manganesífero da série) se desenvolve em umdomínio de fugacidade de oxigênio moderado e de fugacidade do enxofre suficientemente extenso e comparável àquele dagenthelvita.A formação de mineralização de berílio de composição variável nos skarns resultaria, seja da sucessão de soluções tardiasricas em sílica (se a razão Si/Al é alta, a fenaquita ou a helvita se cristalizam) atuando sobre a paragênese aluminosa (musgravita,crisoberilo) formada precocemente, seja da fraca migração de Al em relação a Si. Neste último caso, a paragênese aluminosa(musgravita, crisoberilo) terá uma distribuição limitada. A atividade da alumina desempenha um papel essencial na variação dacomposição dos minerais de berílio. Se ela é fraca, a fenaquita e/ou helvita são estáveis e se ela é forte o berilo e o crisoberilo oua musgravita são estáveis.Entretanto, o aumento da atividade de alguns elementos (Ca, Mn, Fe, Zn ou alcalinos) tendendo a incorporarem alumina nasgranadas ou nos feldspatos será um fator desfavorável para a formação do berilo. Assim, a helvita é um mineral tipicamenteestável nos skarns cálcicos e se associa à fenaquita nas rochas submetidas ao metassomatismo alcalino. Por outro lado, o beriloaparece normalmente em condições onde um fluido ácido se separa de líquidos graníticos muito evoluidos (aplopegmatito).A genthelvita é estável sob condições alcalinas e oxidantes. ABSTRACT: Beryllium-bearing minerals (beryl, phenacite, helvite) are present in the quartz-muscovite and siderophyllite veins. In thealbitites, only phenacite and helvite (Fe,Zn,Mn)8Be6(SiO4)6S2 are found. Besides the Sucuri deposits, we studied also helvitesfrom the northern skarn of Costabonne (France) and from quartz-wolframite veins of Dajishan (China). Paragenetic and geochemicaldata on helvites from these three occurences lead to propose a new structural formula:(Mn,Zn,Fe)8-xNax Be6 Si6 O24 S2-xClx, analogous to that of haüyne.To the standard substitutions Zn-Fe-Mn in helvite, we may add substitutions like Cl-S and Be-Li. Lithium probably replacesberyllium in the structure of helvite, the charge deficit being balanced by the entry of sodium. Crystal chemical constraints clearlyplay an important role for the incorporation of REE in helvite, but, in an alkaline context, helvite shows preference for heavyREE.Danalite (the Fe end-member of helvite) is stable in a very limited domain of fS2 and fO2, which coincides with that ofpyrrhotite. Genthelvite (Zn end-member) is stable in a large domain of fS2 and fO2. On the other hand, helvite (Mn end-member)is stable in conditions of moderate fO2 and for a range of fS2 relatively large compared to that of genthelvite. In Sucuri,Goiás,Brazil, the ilmenites of the internal zone (where genthelvite is found) contain 16% of hematite, whereas those of the external zonecontain no hematite. The zonations observed within the helvite crystals (genthelvite core and danalite border) reflect the variationsof fS2 and fO2.The compositional variations of the beryllium minerals observed in skarns may be explained by the following processes:- either a late arrival of silica-rich solutions (high Si/Al ratio, presence of phenacite or helvite) within early formed aluminarichparageneses (musgravite, chrysoberyl),- or a limited mobility of Al relatively to Si, which would induce a limited extension of the aluminous parageneses (musgravite,chrysoberyl).The activity of aluminium plays an essential role in the stability of the beryllium minerals: phenacite and/or helvite are stablewhen it is low, and beryl, chrysoberyl or musgravite when it is high. However, the increase of activity of other elements (Ca, Mn,Fe, Zn, alkalis) that would induce the formation of minerals incorporating alumina (garnet or felspars) would be unfavourable tothe formation of beryl. Helvite is thus typically stable in calcic skarns, and it is associated with phenacite in the rocks submittedto alkaline metasomatism. Beryl, on the contrary, normally appears when acidic fluids separates from highly evolved graniticmagmas (aplopegmatitic stage).The zonation of helvite crystals in albitites (genthelvite core, danalite border) reflects the decrease of alkalinity of the fluids.This zonation on the crystal scale is also observed on the outcrop scale: helvite composition varies from Ge64Da10He26 in theinternal zone to Ge23Da50He26 in the external zone. The same variation is observed in an albitized siderophyllite vein, fromGe25Da42He33 in a slightly albitized zone to Ge55Da39He22 in a highly albitized one. The formation of genthelvite is favoured, ascompared with the other members of the helvite group, by alkaline conditions.The compositional variations of helvite in the Sucuri massif would result from variations in fS2 and fO2 in the fluids. Genthelviteis stable under alkaline and oxydizing conditions.