I. Lykova, R. Rowe, G. Poirier, G. Giester, Kelsie Ojaste, H. Friis
Abstract. The mckelveyite group consisting of seven carbonate minerals – mckelveyite-(Y), ewaldite, weloganite, donnayite-(Y), alicewilsonite-(YCe), alicewilsonite-(YLa), and bainbridgeite-(YCe) – is formally established. The general formula of the minerals is A3B3(CO3)6 ⋅ 3H2O, where A= Na, Ca, Y, and Zr and B= Sr, Ba, Ce, and La. Different order–disorder modifications are known resulting in triclinic, monoclinic, hexagonal, and trigonal minerals with essentially the same structure. Re-examination of donnayite-(Y) type specimens shows that the original description contains data collected on two different species: donnayite-(Y) and alicewilsonite-(YCe). Donnayite-(Y), NaCaSr3Y(CO3)6 ⋅ 3H2O, was found in only one specimen out of seven – CMNMC 39396 – housed at the Canadian Museum of Nature, Ottawa. This specimen becomes the holotype of donnayite-(Y). The crystal structure of donnayite-(Y) was solved and refined to R1= 0.055 for 3366 reflections with I>2σ(I). Donnayite-(Y) is shown to have a weloganite-type structure confirming its place in the mckelveyite group.
{"title":"Mckelveyite group minerals – Part 1: Nomenclature and new data on donnayite-(Y)","authors":"I. Lykova, R. Rowe, G. Poirier, G. Giester, Kelsie Ojaste, H. Friis","doi":"10.5194/ejm-35-133-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-133-2023","url":null,"abstract":"Abstract. The mckelveyite group consisting of seven carbonate\u0000minerals – mckelveyite-(Y), ewaldite, weloganite, donnayite-(Y),\u0000alicewilsonite-(YCe), alicewilsonite-(YLa), and bainbridgeite-(YCe) – is\u0000formally established. The general formula of the minerals is\u0000A3B3(CO3)6 ⋅ 3H2O, where A= Na, Ca, Y, and Zr\u0000and B= Sr, Ba, Ce, and La. Different order–disorder modifications are known\u0000resulting in triclinic, monoclinic, hexagonal, and trigonal minerals with\u0000essentially the same structure. Re-examination of donnayite-(Y) type\u0000specimens shows that the original description contains data collected on two\u0000different species: donnayite-(Y) and alicewilsonite-(YCe). Donnayite-(Y),\u0000NaCaSr3Y(CO3)6 ⋅ 3H2O, was found in only one\u0000specimen out of seven – CMNMC 39396 – housed at the Canadian Museum of\u0000Nature, Ottawa. This specimen becomes the holotype of donnayite-(Y). The\u0000crystal structure of donnayite-(Y) was solved and refined to R1= 0.055 for 3366 reflections with I>2σ(I). Donnayite-(Y) is\u0000shown to have a weloganite-type structure confirming its place in the\u0000mckelveyite group.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49580136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Using the diffusion couple technique, diffusion of CO2 in a leucititic melt from the Colli Albani Volcanic District in Italy was investigated at temperatures between 1200 and 1350 ∘C in an internally heated pressure vessel at 300 MPa. To examine the effect of dissolved H2O in the melt, experiments were performed for a nominally dry melt (0.18 ± 0.03 wt % H2O) and for a hydrous melt containing 3.36 ± 0.28 wt % H2O. Diffusion experiments were run for 40 to 120 min and terminated by rapid quench. CO2 concentration profiles were subsequently measured via attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and fitted with error functions to obtain individual diffusion coefficients. For the anhydrous and hydrous sample series, seven diffusion coefficients were determined each. Diffusivity was found to increase exponentially with temperature for both melts following an Arrhenius behaviour. The Arrhenius equation for the nominally dry leucititic melt is described by logDCO2=-1.44(±0.24)⋅10000T-1.95(±1.59), where DCO2 is the diffusion coefficient in m2 s−1 and T is the temperature in K. In the experimental temperature range, H2O has an accelerating effect on CO2 diffusion. At 1200 ∘C, diffusivity increases from 1.94 × 10−12 m2 s−1 in the dry melt to 1.54 × 10−11 m2 s−1 in the hydrous melt. The Arrhenius equation for the leucititic melt containing 3.36±0.28 wt % H2O is given by logDCO2=-1.09(±0.30)⋅10000T-3.41(±1.99). The activation energies for CO2 were determined to be 275 ± 47 kJ mol−1 for the anhydrous melt and 209 ± 58 kJ mol−1 for the hydrous melt. The high CO2 activation energy in the leucititic melt indicates that the diffusion might be partly attributed to the carbonate species. At high magmatic temperatures above 1200 ∘C, CO2 diffusivity in the leucititic melt is only slightly lower than CO2 diffusion in rhyolitic and basaltic melts, suggesting that CO2 diffusion in natural melts is relatively independent from the bulk melt composition at such temperatures. CO2 diffuses slower than other volatile components such as halogens and H2O in depolymerized silicate melts. Thus, a fractionation of volatiles can occur during magma ascent and degassing. The experimental data on CO2 diffusion can be used for modelling the degassing mechanisms of ultrapotassic mafic melts.
{"title":"CO2 diffusion in dry and hydrous leucititic melt","authors":"Lennart Koch, B. Schmidt","doi":"10.5194/ejm-35-117-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-117-2023","url":null,"abstract":"Abstract. Using the diffusion couple technique, diffusion of\u0000CO2 in a leucititic melt from the Colli Albani Volcanic District in\u0000Italy was investigated at temperatures between 1200 and 1350 ∘C\u0000in an internally heated pressure vessel at 300 MPa. To examine the effect of\u0000dissolved H2O in the melt, experiments were performed for a nominally\u0000dry melt (0.18 ± 0.03 wt % H2O) and for a hydrous melt\u0000containing 3.36 ± 0.28 wt % H2O. Diffusion experiments were run\u0000for 40 to 120 min and terminated by rapid quench. CO2 concentration\u0000profiles were subsequently measured via attenuated total reflection\u0000Fourier transform infrared spectroscopy (ATR-FTIR) and fitted with error\u0000functions to obtain individual diffusion coefficients. For the anhydrous and hydrous sample series, seven diffusion coefficients\u0000were determined each. Diffusivity was found to increase exponentially with\u0000temperature for both melts following an Arrhenius behaviour. The Arrhenius\u0000equation for the nominally dry leucititic melt is described by logDCO2=-1.44(±0.24)⋅10000T-1.95(±1.59), where DCO2 is the diffusion coefficient in m2 s−1 and T is the\u0000temperature in K. In the experimental temperature range, H2O has an\u0000accelerating effect on CO2 diffusion. At 1200 ∘C,\u0000diffusivity increases from 1.94 × 10−12 m2 s−1 in\u0000the dry melt to 1.54 × 10−11 m2 s−1 in the hydrous\u0000melt. The Arrhenius equation for the leucititic melt containing 3.36±0.28 wt % H2O is given by logDCO2=-1.09(±0.30)⋅10000T-3.41(±1.99). The activation energies for CO2 were determined to be 275 ± 47 kJ mol−1 for the anhydrous melt and 209 ± 58 kJ mol−1 for the\u0000hydrous melt. The high CO2 activation energy in the leucititic melt indicates that\u0000the diffusion might be partly attributed to the carbonate species. At high\u0000magmatic temperatures above 1200 ∘C, CO2 diffusivity in the\u0000leucititic melt is only slightly lower than CO2 diffusion in rhyolitic\u0000and basaltic melts, suggesting that CO2 diffusion in natural melts is\u0000relatively independent from the bulk melt composition at such temperatures.\u0000CO2 diffuses slower than other volatile components such as halogens and\u0000H2O in depolymerized silicate melts. Thus, a fractionation of volatiles\u0000can occur during magma ascent and degassing. The experimental data on\u0000CO2 diffusion can be used for modelling the degassing mechanisms of\u0000ultrapotassic mafic melts.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45155594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Balan, G. Radtke, C. Fourdrin, L. Paulatto, H. A. Horn, Y. Fuchs
Abstract. The OH-stretching infrared absorption spectrum of a tourmaline sample close to the foitite end-member is interpreted in the light of the density functional theory (DFT) modeling of iron-bearing Y3Z6 clusters in tourmaline. The iron-bearing clusters reflect the Al-rich and Na-deficient character of foitite and contain either two Fe2+ and one Al3+ or one Fe2+ and two Al3+ ions at the Y sites. The clusters are embedded in a tourmaline host structure with dravite composition. For the iron dimer models, the structural and vibrational properties corresponding to the ferromagnetic (FM) or anti-ferromagnetic (AFM) arrangement of the iron spins and the effect of vacancy ordering along the [001] axis are considered. A significant difference in the relaxed structure of the FM and AFM clusters is observed, stemming from the electron delocalization and Fe–Fe bonding interactions in the FM cluster. These bonding interactions are not allowed in the AFM cluster. In this case, the valence electrons with opposite spins remain separately localized on the two Fe atoms. The AFM configuration is more stable than the FM one in the theoretical models, provided that the description of the on-site Coulomb repulsion in Fe(3d) orbitals is improved within the DFT + U framework. Based on the theoretical results, the two bands at 3630 and 3644 cm−1 in the vibrational spectra of iron-rich and Na-deficient tourmalines are assigned to WOH groups associated with YFe22+YAl3+ environments with an AFM coupling of Fe ions and surrounded by one and two vacant X sites, respectively. The two major VOH bands of the experimental spectrum are interpreted on the same basis, and these interpretations are extrapolated to Mn-bearing tourmalines.
{"title":"Effect of Fe–Fe interactions and X-site vacancy ordering on the OH-stretching spectrum of foitite","authors":"E. Balan, G. Radtke, C. Fourdrin, L. Paulatto, H. A. Horn, Y. Fuchs","doi":"10.5194/ejm-35-105-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-105-2023","url":null,"abstract":"Abstract. The OH-stretching infrared absorption spectrum of a tourmaline sample close\u0000to the foitite end-member is interpreted in the light of the density\u0000functional theory (DFT) modeling of iron-bearing Y3Z6 clusters in\u0000tourmaline. The iron-bearing clusters reflect the Al-rich and Na-deficient\u0000character of foitite and contain either two Fe2+ and one Al3+ or\u0000one Fe2+ and two Al3+ ions at the Y sites. The clusters are\u0000embedded in a tourmaline host structure with dravite composition. For the\u0000iron dimer models, the structural and vibrational properties corresponding\u0000to the ferromagnetic (FM) or anti-ferromagnetic (AFM) arrangement of the\u0000iron spins and the effect of vacancy ordering along the [001] axis are\u0000considered. A significant difference in the relaxed structure of the FM and\u0000AFM clusters is observed, stemming from the electron delocalization and\u0000Fe–Fe bonding interactions in the FM cluster. These bonding interactions are\u0000not allowed in the AFM cluster. In this case, the valence electrons with\u0000opposite spins remain separately localized on the two Fe atoms. The AFM\u0000configuration is more stable than the FM one in the theoretical models,\u0000provided that the description of the on-site Coulomb repulsion in Fe(3d)\u0000orbitals is improved within the DFT + U framework. Based on the theoretical\u0000results, the two bands at 3630 and 3644 cm−1 in the vibrational spectra\u0000of iron-rich and Na-deficient tourmalines are assigned to WOH groups\u0000associated with YFe22+YAl3+ environments with an\u0000AFM coupling of Fe ions and surrounded by one and two vacant X sites,\u0000respectively. The two major VOH bands of the experimental spectrum are\u0000interpreted on the same basis, and these interpretations are extrapolated to\u0000Mn-bearing tourmalines.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49237599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Hochleitner, Christian Rewitzer, I. Grey, W. G. Mumme, C. MacRae, A. R. Kampf, E. Keck, R. Gable, A. Glenn
Abstract. Whiteite-(CaMnFe), CaMn2+Fe22+Al2(PO4)4(OH)2 ⋅ 8H2O, is a new whiteite-subgroup member of the jahnsite group from the Hagendorf-Süd pegmatite, Oberpfalz, Bavaria, Germany. It was found in vugs in an altered feldspar area of a specimen composed predominantly of rockbridgeite, with hureaulite and relic triphylite. Other associated minerals in small vugs in the specimen were strengite and laueite. Whiteite-(CaMnFe) occurs as sprays and clusters of colourless to pale yellow, rod-like crystals, with diameters of typically 10 to 50 µm and lengths up to ∼ 500 µm. The crystals are flattened on {001} and elongated along [010]. The measured density is 2.80(2) g cm−3. Optically, whiteite-(CaMnFe) crystals are biaxial (+), with α=1.608(3), β=1.612(3), γ=1.624(3) and 2V(meas.) = 59(1)∘. The empirical formula from electron microprobe analyses and structure refinement is (Ca0.70Mn0.30)Mn(Fe1.232+Mn0.49Mg0.29Zn0.06)(Al1.88Fe0.123+)(PO4)3.96(OH)2(H2O)8. Whiteite-(CaMnFe) is monoclinic, P2 /a, a=14.925(5), b=7.0100(14), c=10.053(2) Å, β=111.31(2)∘, V=979.9(4) Å3 and Z=2. The crystal structure was refined using single-crystal data to wRobs=0.052 for 1613 reflections with I>3σ(I). Site occupancy refinements confirm the ordering of dominant Ca, Mn and Fe2+ in the X, M1 and M2 sites, respectively, of the general jahnsite-group formula XM1M22M32(H2O)8(OH)2(PO4)4.
{"title":"Whiteite-(CaMnFe), a new jahnsite-group mineral from the Hagendorf-Süd pegmatite, Oberpfalz, Bavaria","authors":"R. Hochleitner, Christian Rewitzer, I. Grey, W. G. Mumme, C. MacRae, A. R. Kampf, E. Keck, R. Gable, A. Glenn","doi":"10.5194/ejm-35-95-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-95-2023","url":null,"abstract":"Abstract. Whiteite-(CaMnFe),\u0000CaMn2+Fe22+Al2(PO4)4(OH)2 ⋅ 8H2O, is a new whiteite-subgroup member of the jahnsite group from the\u0000Hagendorf-Süd pegmatite, Oberpfalz, Bavaria, Germany. It was found in\u0000vugs in an altered feldspar area of a specimen composed predominantly of\u0000rockbridgeite, with hureaulite and relic triphylite. Other associated\u0000minerals in small vugs in the specimen were strengite and laueite.\u0000Whiteite-(CaMnFe) occurs as sprays and clusters of colourless to pale\u0000yellow, rod-like crystals, with diameters of typically 10 to 50 µm\u0000and lengths up to ∼ 500 µm. The crystals are flattened\u0000on {001} and elongated along [010]. The measured\u0000density is 2.80(2) g cm−3. Optically, whiteite-(CaMnFe)\u0000crystals are biaxial (+), with α=1.608(3), β=1.612(3), γ=1.624(3) and 2V(meas.) = 59(1)∘. The\u0000empirical formula from electron microprobe analyses and structure refinement\u0000is\u0000(Ca0.70Mn0.30)Mn(Fe1.232+Mn0.49Mg0.29Zn0.06)(Al1.88Fe0.123+)(PO4)3.96(OH)2(H2O)8.\u0000Whiteite-(CaMnFe) is monoclinic, P2 /a, a=14.925(5), b=7.0100(14), c=10.053(2) Å, β=111.31(2)∘, V=979.9(4) Å3 and Z=2. The crystal structure was refined using\u0000single-crystal data to wRobs=0.052 for 1613 reflections with I>3σ(I). Site occupancy refinements confirm the ordering\u0000of dominant Ca, Mn and Fe2+ in the X, M1 and M2 sites, respectively, of\u0000the general jahnsite-group formula\u0000XM1M22M32(H2O)8(OH)2(PO4)4.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49035447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Biagioni, F. Bosi, D. Mauro, H. Skogby, A. Dini, F. Zaccarini
Abstract. The new tourmaline supergroup mineral dutrowite, Na(Fe2.52+Ti0.5)Al6(Si6O18)(BO3)3(OH)3O, has been discovered in an outcrop of a Permian metarhyolite near the hamlet of Fornovolasco, Apuan Alps, Tuscany, Italy. It occurs as chemically homogeneous domains, up to 0.5 mm, brown in colour, with a light-brown streak and a vitreous lustre, within anhedral to subhedral prismatic crystals, up to 1 mm in size, closely associated with Fe-rich oxy-dravite. Dutrowite is trigonal, space group R3m, with a=15.9864(8), c=7.2187(4) Å, V=1597.68(18) Å3, and Z=3. The crystal structure was refined to R1=0.0257 for 1095 unique reflections with Fo>4σ (Fo) and 94 refined parameters. Electron microprobe analysis, coupled with Mössbauer spectroscopy, resulted in the empirical structural formula X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.252+Mg0.76Ti0.56Al0.42)Σ3.00 Z(Al4.71Fe0.273+V0.023+Mg0.82Fe0.182+)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18] (BO3)3O(3)(OH)3O(1)[O0.59(OH)0.41]Σ1.00, which was recast in the empirical ordered formula, required for classification purposes: X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.432+Mg1.00Ti0.56)Σ3.00 Z(Al5.13Fe0.273+V0.023+Mg0.58)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18] (BO3)3V(OH)3 W[O0.59(OH)0.41]Σ1.00. Dutrowite is an oxy-species belonging to the alkali group of the tourmaline supergroup. Titanium is hosted in octahedral coordination, and its incorporation is probably due to the substitution 2Al3+ = Ti4+ + (Fe,Mg)2+. Its occurrence seems to be related to late-stage high-T/low-P replacement of “biotite” during the late-magmatic/hydrothermal evolution of the Permian metarhyolite.
{"title":"Dutrowite, Na(Fe2+2.5Ti0.5)Al6(Si6O18)(BO3)3(OH)3O, a new mineral from the Apuan Alps (Tuscany, Italy): the first member of the tourmaline supergroup with Ti as a species-forming chemical constituent","authors":"C. Biagioni, F. Bosi, D. Mauro, H. Skogby, A. Dini, F. Zaccarini","doi":"10.5194/ejm-35-81-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-81-2023","url":null,"abstract":"Abstract. The new tourmaline supergroup mineral dutrowite,\u0000Na(Fe2.52+Ti0.5)Al6(Si6O18)(BO3)3(OH)3O,\u0000has been discovered in an outcrop of a Permian metarhyolite near the hamlet\u0000of Fornovolasco, Apuan Alps, Tuscany, Italy. It occurs as chemically\u0000homogeneous domains, up to 0.5 mm, brown in colour, with a light-brown streak\u0000and a vitreous lustre, within anhedral to subhedral prismatic crystals, up\u0000to 1 mm in size, closely associated with Fe-rich oxy-dravite. Dutrowite is\u0000trigonal, space group R3m, with a=15.9864(8), c=7.2187(4) Å, V=1597.68(18) Å3, and Z=3. The crystal structure was refined to\u0000R1=0.0257 for 1095 unique reflections with Fo>4σ (Fo) and 94 refined parameters. Electron microprobe analysis,\u0000coupled with Mössbauer spectroscopy, resulted in the empirical\u0000structural formula X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.252+Mg0.76Ti0.56Al0.42)Σ3.00 Z(Al4.71Fe0.273+V0.023+Mg0.82Fe0.182+)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18]\u0000(BO3)3O(3)(OH)3O(1)[O0.59(OH)0.41]Σ1.00, which was recast in the\u0000empirical ordered formula, required for classification purposes:\u0000X(Na0.81Ca0.20K0.01)Σ1.02 Y(Fe1.432+Mg1.00Ti0.56)Σ3.00 Z(Al5.13Fe0.273+V0.023+Mg0.58)Σ6.00 T[(Si5.82Al0.18)Σ6.00O18]\u0000(BO3)3V(OH)3 W[O0.59(OH)0.41]Σ1.00. Dutrowite is an\u0000oxy-species belonging to the alkali group of the tourmaline supergroup.\u0000Titanium is hosted in octahedral coordination, and its incorporation is\u0000probably due to the substitution 2Al3+ = Ti4+ + (Fe,Mg)2+. Its occurrence seems to be related to late-stage\u0000high-T/low-P replacement of “biotite” during the\u0000late-magmatic/hydrothermal evolution of the Permian metarhyolite.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45306201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pete Williams, Frédéric Hatert, Marco Pasero, Stuart Mills
{"title":"IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) – Newsletter 71","authors":"Pete Williams, Frédéric Hatert, Marco Pasero, Stuart Mills","doi":"10.5194/ejm-35-75-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-75-2023","url":null,"abstract":"","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136372236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yanjuan Wang, F. Nestola, Z. Hou, X. Gu, G. Dong, Zhusen Yang, Guang Fan, Zhibin Xiao, Kai Qu
Abstract. A second occurrence of bobtraillite is described from the Gejiu nepheline syenite, southwestern China. The extremely rare and complex boron-bearing zirconium silicate is associated with albite, orthoclase, jadeite, fluorite, andradite, titanite, as well as other REE and zirconium-bearing minerals, catapleiite, moxuanxueite, låvenite, eudialyte, britholite-(Ce), and calcioancylite-(La). The EMP and LA-ICP-MS analyses of the studied material give an empirical formula: (Na9.70Li0.42K0.08□1.80)Σ12.00(Sr10.61Ca1.14Fe0.07□0.18)Σ12.00(Zr12.87Ti0.53Nb0.31REE0.08Y0.06U0.02Th0.01□0.12)Σ14.00(Si42.41B5.59Al0.02)Σ48.02O132(OH)12 ⚫ 12H2O. Bobtraillite is trigonal, with space group P3¯c1, a=19.6977(6), c=9.9770(3) Å, V=3352.4(2) Å3, Z=1. Single-crystal structure refinement revealed that all sodium occupies the Na(1) and Na(2) sites; the site occupancy of these two positions is 0.835(18) and 0.15(2), respectively, suggesting that Na(1) site is Na dominant, while Na(2) is a vacancy-dominant site. The [8]-coordinated site has been assigned to Sr and Ca, with free occupancy factors, 0.874(10) and 0.126(10), respectively. These new data indicate that the ideal formula of bobtraillite could be written as (Na,□)12(□,Na)12Sr12Zr14(Si3O9)10[Si2BO7(OH)2]6 ⚫ 12H2O.
{"title":"Bobtraillite from Gejiu hyperagpaitic nepheline syenite, southwestern China: new occurrence and crystal structure","authors":"Yanjuan Wang, F. Nestola, Z. Hou, X. Gu, G. Dong, Zhusen Yang, Guang Fan, Zhibin Xiao, Kai Qu","doi":"10.5194/ejm-35-65-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-65-2023","url":null,"abstract":"Abstract. A second occurrence of bobtraillite is described from the\u0000Gejiu nepheline syenite, southwestern China. The extremely rare and complex\u0000boron-bearing zirconium silicate is associated with albite, orthoclase,\u0000jadeite, fluorite, andradite, titanite, as well as other REE and\u0000zirconium-bearing minerals, catapleiite, moxuanxueite, låvenite,\u0000eudialyte, britholite-(Ce), and calcioancylite-(La). The EMP and LA-ICP-MS\u0000analyses of the studied material give an empirical formula:\u0000(Na9.70Li0.42K0.08□1.80)Σ12.00(Sr10.61Ca1.14Fe0.07□0.18)Σ12.00(Zr12.87Ti0.53Nb0.31REE0.08Y0.06U0.02Th0.01□0.12)Σ14.00(Si42.41B5.59Al0.02)Σ48.02O132(OH)12 ⚫ 12H2O. Bobtraillite is trigonal,\u0000with space group P3¯c1, a=19.6977(6), c=9.9770(3) Å, V=3352.4(2) Å3, Z=1. Single-crystal structure refinement revealed\u0000that all sodium occupies the Na(1) and Na(2) sites; the site occupancy of\u0000these two positions is 0.835(18) and 0.15(2), respectively, suggesting that\u0000Na(1) site is Na dominant, while Na(2) is a vacancy-dominant site. The\u0000[8]-coordinated site has been assigned to Sr and Ca, with free\u0000occupancy factors, 0.874(10) and 0.126(10), respectively. These new data\u0000indicate that the ideal formula of bobtraillite could be written as\u0000(Na,□)12(□,Na)12Sr12Zr14(Si3O9)10[Si2BO7(OH)2]6 ⚫ 12H2O.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48376475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. When measuring boron (B) in tourmalines calibrated with schorl, no deviations in the peak intensities could be detected with a proven analysis protocol and using the Mo/B4C multilayer crystal LDEB. It is only when boron is detected in natural and experimental samples, some with significantly lower boron concentrations than in tourmalines, that irregularities in the analysis become visible. This phenomenon is known but has not been analytically investigated so far. Using four natural and artificial solids with boron concentrations from 0.035 wt %–3.14 wt % B, an apparent linear trend line was drawn. The intersect of that trend line with the y axis represents the detection limit of boron, which is of about 0.25 wt % B. The discrepancy between the apparent and the true value trend lines at boron concentrations of 0.25 wt %–2.1 wt % B shows that a correction is necessary. At higher boron concentrations, the discrepancy between the apparent and true value trend lines is within the uncertainty of electron microprobe analysis (EPMA) and disappears completely up to boron concentrations of about 3 wt %.
{"title":"Appearance, study and a possible correction for boron: a phenomenon in ultra-soft X-ray measurements using a synthetic multilayer crystal and the EPMA","authors":"F. Wilke","doi":"10.5194/ejm-35-59-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-59-2023","url":null,"abstract":"Abstract. When measuring boron (B) in tourmalines calibrated with schorl, no deviations in\u0000the peak intensities could be detected with a proven analysis protocol and\u0000using the Mo/B4C multilayer crystal LDEB. It is only when boron is detected\u0000in natural and experimental samples, some with significantly lower boron\u0000concentrations than in tourmalines, that irregularities in the analysis\u0000become visible. This phenomenon is known but has not been analytically\u0000investigated so far. Using four natural and artificial solids with boron\u0000concentrations from 0.035 wt %–3.14 wt % B, an apparent linear trend line was\u0000drawn. The intersect of that trend line with the y axis represents the\u0000detection limit of boron, which is of about 0.25 wt % B. The discrepancy\u0000between the apparent and the true value trend lines at boron concentrations of\u00000.25 wt %–2.1 wt % B shows that a correction is necessary. At higher boron\u0000concentrations, the discrepancy between the apparent and true value\u0000trend lines is within the uncertainty of electron microprobe analysis (EPMA) and disappears\u0000completely up to boron concentrations of about 3 wt %.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46106627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ashim Rijal, L. Cobden, J. Trampert, H. Marquardt, J. Jackson
Abstract. Shear properties of mantle minerals are vital for interpreting seismic shear wave speeds and therefore inferring the composition and dynamics of a planetary interior. Shear wave speed and elastic tensor components, from which the shear modulus can be computed, are usually measured in the laboratory mimicking the Earth's (or a planet's) internal pressure and temperature conditions. A functional form that relates the shear modulus to pressure (and temperature) is fitted to the measurements and used to interpolate within and extrapolate beyond the range covered by the data. Assuming a functional form provides prior information, and the constraints on the predicted shear modulus and its uncertainties might depend largely on the assumed prior rather than the data. In the present study, we propose a data-driven approach in which we train a neural network to learn the relationship between the pressure, temperature and shear modulus from the experimental data without prescribing a functional form a priori. We present an application to MgO, but the same approach works for any other mineral if there are sufficient data to train a neural network. At low pressures, the shear modulus of MgO is well-constrained by the data. However, our results show that different experimental results are inconsistent even at room temperature, seen as multiple peaks and diverging trends in probability density functions predicted by the network. Furthermore, although an explicit finite-strain equation mostly agrees with the likelihood predicted by the neural network, there are regions where it diverges from the range given by the networks. In those regions, it is the prior assumption of the form of the equation that provides constraints on the shear modulus regardless of how the Earth behaves (or data behave). In situations where realistic uncertainties are not reported, one can become overconfident when interpreting seismic models based on those defined equations of state. In contrast, the trained neural network provides a reasonable approximation to experimental data and quantifies the uncertainty from experimental errors, interpolation uncertainty, data sparsity and inconsistencies from different experiments.
{"title":"Shear properties of MgO inferred using neural networks","authors":"Ashim Rijal, L. Cobden, J. Trampert, H. Marquardt, J. Jackson","doi":"10.5194/ejm-35-45-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-45-2023","url":null,"abstract":"Abstract. Shear properties of mantle minerals are vital for interpreting seismic shear wave speeds and therefore inferring the composition and dynamics of a planetary interior. Shear wave speed and elastic tensor components, from which the shear modulus can be computed, are usually measured in the laboratory mimicking the Earth's (or a planet's) internal pressure and temperature conditions. A functional form that relates the shear modulus to pressure (and temperature) is fitted to the measurements and used to interpolate within and extrapolate beyond the range covered by the data. Assuming a functional form provides prior information, and the constraints on the predicted shear modulus and its uncertainties might depend largely on the assumed prior rather than the data. In the present study, we propose a data-driven approach in which we train a neural network to learn the relationship between the pressure, temperature and shear modulus from the experimental data without prescribing a functional form a priori. We present an application to MgO, but the same approach works for any other mineral if there are sufficient data to train a neural network. At low pressures, the shear modulus of MgO is well-constrained by the data. However, our results show that different experimental results are inconsistent even at room temperature, seen as multiple peaks and diverging trends in probability density functions predicted by the network. Furthermore, although an explicit finite-strain equation mostly agrees with the likelihood predicted by the neural network, there are regions where it diverges from the range given by the networks. In those regions, it is the prior assumption of the form of the equation that provides constraints on the shear modulus regardless of how the Earth behaves (or data behave). In situations where realistic uncertainties are not reported, one can become overconfident when interpreting seismic models based on those defined equations of state. In contrast, the trained neural network provides a reasonable approximation to experimental data and quantifies the uncertainty from experimental errors, interpolation uncertainty, data sparsity and inconsistencies from different experiments.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45618885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Authigenic epidote supergroups are an abundant accessory mineral in the calcium–aluminum silicate and thermometamorphic hydrothermal zones of the Campi Flegrei (Phlegraean Fields) geothermal field located west of Naples, Italy. Geothermal exploration for high-enthalpy fluid produced drill core and cuttings to ∼ 3 km depth in the Mofete (MF1, MF2, MF5) and San Vito (SV1, SV3) wells, where measured down-hole temperatures of epidote-bearing samples range from 270–350 ∘C and from 285–390 ∘C for the Mofete and San Vito areas, respectively. Two epidote group (epidote, clinozoisite), some rare earth element (REE)-bearing, and two allanite group (allanite-(Ce), ferriallanite-(Ce)) minerals were identified by electron microprobe. The allanite group is light rare earth element (LREE, La–Gd) enriched, Ce dominant, with REE + Y that varies from 30.59 wt %–14.32 wt %. Complex compositional variation such as oscillatory, sector, and complex (mixed) zoning is a ubiquitous feature observed in the epidote group, which occurs as veins, in vugs, as various size masses, and as isolated single crystals. Compositional zoning is caused by variable Fe ↔ Al3+ substitution and XFe [(Fe3+) / (Fe3++ Al)] ranges from 0.06–0.33 (Fe3+=0.185–0.967 apfu). XFe tends to decrease with increasing temperature in the Mofete wells, but its distribution is more complex in the San Vito wells, which records recent fault displacement. The variety and complexity of the epidote supergroup zoning suggest rapid fluid composition and/or intensive parameter fluctuations in the local hydrothermal system.
{"title":"Compositional variation and zoning of epidote supergroup minerals in the Campi Flegrei geothermal field, Naples, Italy","authors":"H. Belkin, B. De Vivo","doi":"10.5194/ejm-35-25-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-25-2023","url":null,"abstract":"Abstract. Authigenic epidote supergroups are an abundant accessory mineral in the\u0000calcium–aluminum silicate and thermometamorphic hydrothermal zones of the\u0000Campi Flegrei (Phlegraean Fields) geothermal field located west of Naples,\u0000Italy. Geothermal exploration for high-enthalpy fluid produced drill core\u0000and cuttings to ∼ 3 km depth in the Mofete (MF1, MF2, MF5) and\u0000San Vito (SV1, SV3) wells, where measured down-hole temperatures of\u0000epidote-bearing samples range from 270–350 ∘C and from\u0000285–390 ∘C for the Mofete and San Vito areas, respectively. Two\u0000epidote group (epidote, clinozoisite), some rare earth element\u0000(REE)-bearing, and two allanite group (allanite-(Ce), ferriallanite-(Ce))\u0000minerals were identified by electron microprobe. The allanite group is light\u0000rare earth element (LREE, La–Gd) enriched, Ce dominant, with REE + Y that\u0000varies from 30.59 wt %–14.32 wt %. Complex compositional variation such as\u0000oscillatory, sector, and complex (mixed) zoning is a ubiquitous feature\u0000observed in the epidote group, which occurs as veins, in vugs, as various\u0000size masses, and as isolated single crystals. Compositional zoning is caused\u0000by variable Fe ↔ Al3+ substitution and XFe [(Fe3+) / (Fe3++ Al)] ranges from 0.06–0.33 (Fe3+=0.185–0.967 apfu). XFe tends to decrease with increasing temperature\u0000in the Mofete wells, but its distribution is more complex in the San Vito\u0000wells, which records recent fault displacement. The variety and complexity\u0000of the epidote supergroup zoning suggest rapid fluid composition and/or\u0000intensive parameter fluctuations in the local hydrothermal system.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71223644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：