Abstract. The factors affecting the calibration of pressure in the piston–cylinder and other solid-media apparatus are so multifaceted and complex as to challenge existing approaches. Here we demonstrate how MgO–ZnO ceramics may be used in piston–cylinder assemblies to routinely record the pressure–temperature conditions experienced by samples in each run. The miscibility gap between rock-salt- and wurtzite-structured phases in the binary system MgO–ZnO is well suited for this purpose as it is capable of recording pressure and/or temperature in situ with a typical sensitivity to pressure of ± 0.02 GPa (1 standard deviation) if temperature is known, or variations in temperature around a sample of ∼ 10 °C assuming pressure is constant. MgO–ZnO ceramics can simply replace the widely used MgO surrounding samples under most conditions, since they are almost as inert chemically as MgO and have similar mechanical properties. As a demonstration, we apply the method to a redetermination of the quartz–coesite univariant phase transition in the piston–cylinder, using different assembly materials, sizes, and pressure–temperature path protocols. Continuous monitoring of piston travel during the entirety of each run helps reveal the differences in behaviour of the apparatus under these variables. We show that several assumptions about the behaviour of the piston–cylinder apparatus are ill-founded, that there may be a discrepancy of ∼ 10 % in pressure between otherwise identical experiments conducted using slightly different experimental protocols, and that the effects of the various options for assembly materials are complex, depending on the pressure–temperature path of the experiment throughout its duration. We have also used the sensitivity of the miscibility gap to temperature to map the temperature distribution in two dimensions surrounding a platinum capsule in a piston–cylinder experiment. The routine inclusion of the ceramic in piston–cylinder assemblies would provide an archive of actual experimental P–T conditions experienced by samples.
{"title":"The use of MgO–ZnO ceramics to record pressure and temperature conditions in the piston–cylinder apparatus","authors":"Nicholas Farmer, Hugh St. C. O'Neill","doi":"10.5194/ejm-36-473-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-473-2024","url":null,"abstract":"Abstract. The factors affecting the calibration of pressure in the piston–cylinder and other solid-media apparatus are so multifaceted and complex as to challenge existing approaches. Here we demonstrate how MgO–ZnO ceramics may be used in piston–cylinder assemblies to routinely record the pressure–temperature conditions experienced by samples in each run. The miscibility gap between rock-salt- and wurtzite-structured phases in the binary system MgO–ZnO is well suited for this purpose as it is capable of recording pressure and/or temperature in situ with a typical sensitivity to pressure of ± 0.02 GPa (1 standard deviation) if temperature is known, or variations in temperature around a sample of ∼ 10 °C assuming pressure is constant. MgO–ZnO ceramics can simply replace the widely used MgO surrounding samples under most conditions, since they are almost as inert chemically as MgO and have similar mechanical properties. As a demonstration, we apply the method to a redetermination of the quartz–coesite univariant phase transition in the piston–cylinder, using different assembly materials, sizes, and pressure–temperature path protocols. Continuous monitoring of piston travel during the entirety of each run helps reveal the differences in behaviour of the apparatus under these variables. We show that several assumptions about the behaviour of the piston–cylinder apparatus are ill-founded, that there may be a discrepancy of ∼ 10 % in pressure between otherwise identical experiments conducted using slightly different experimental protocols, and that the effects of the various options for assembly materials are complex, depending on the pressure–temperature path of the experiment throughout its duration. We have also used the sensitivity of the miscibility gap to temperature to map the temperature distribution in two dimensions surrounding a platinum capsule in a piston–cylinder experiment. The routine inclusion of the ceramic in piston–cylinder assemblies would provide an archive of actual experimental P–T conditions experienced by samples.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141337937","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}
Carina Silke Hanser, Tobias Häger, Roman Botcharnikov
Abstract. Incorporation of ions into the crystal structure of beryl (Be3Al2[Si6O18]) can take place by direct ion-to-ion substitution of the framework components Al3+, Be2+ and Si4+ or by occupation of interstitial or structural channel sites. The most common impurities in beryl include transition metals, alkalis and H2O. It is accepted that the transition metals Mn, Cr and V directly substitute for Al at the octahedral site and induce colour. Similarly, the octahedral site can host Fe instead of Al. Nevertheless, it is shown that it remains disputed whether Fe can also be present at the tetrahedral, interstitial, or channel sites, and opposing hypotheses exist regarding these possibilities. However, in the case of Fe, not only the possible occupation of these sites remains under debate, but also their influence on the subsequent colour of beryl. Similarly, the residence of Li in the channels and at the Be tetrahedral or interstitial tetrahedral sites is still under debate. The presence of more than two types of H2O (type I and type II) in the structural channels of beryl is also unclear. This article aims to give an overview on the consensus and on the current debates found in the literature regarding these aspects. It mainly concentrates on the substitution by and the role of Fe ions and on channel occupancy by H2O.
摘要。离子在绿柱石（Be3Al2[Si6O18]）晶体结构中的掺入可以通过离子对离子直接取代框架成分 Al3+、Be2+ 和 Si4+，或通过占据间隙或结构通道位点来实现。绿柱石中最常见的杂质包括过渡金属、碱和 H2O。一般认为，过渡金属 Mn、Cr 和 V 可直接取代八面体位点上的 Al，并产生颜色。同样，八面体部位也可以容纳铁而不是铝。然而，研究表明，对于铁是否也可以存在于四面体、间隙或沟槽位点仍存在争议，而且对于这些可能性存在着截然相反的假设。不过，就铁而言，不仅这些位点是否可能存在仍有争议，而且它们对绿柱石后续颜色的影响也有争议。同样，锂在通道和 Be 四面体或间隙四面体位点的存在也仍有争议。绿柱石的结构通道中是否存在两种以上的 H2O（I 型和 II 型）也不清楚。本文旨在概述文献中关于这些方面的共识和目前的争论。文章主要集中于铁离子的取代和作用以及 H2O 对通道的占据。
{"title":"Incorporation and substitution of ions and H2O in the structure of beryl","authors":"Carina Silke Hanser, Tobias Häger, Roman Botcharnikov","doi":"10.5194/ejm-36-449-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-449-2024","url":null,"abstract":"Abstract. Incorporation of ions into the crystal structure of beryl (Be3Al2[Si6O18]) can take place by direct ion-to-ion substitution of the framework components Al3+, Be2+ and Si4+ or by occupation of interstitial or structural channel sites. The most common impurities in beryl include transition metals, alkalis and H2O. It is accepted that the transition metals Mn, Cr and V directly substitute for Al at the octahedral site and induce colour. Similarly, the octahedral site can host Fe instead of Al. Nevertheless, it is shown that it remains disputed whether Fe can also be present at the tetrahedral, interstitial, or channel sites, and opposing hypotheses exist regarding these possibilities. However, in the case of Fe, not only the possible occupation of these sites remains under debate, but also their influence on the subsequent colour of beryl. Similarly, the residence of Li in the channels and at the Be tetrahedral or interstitial tetrahedral sites is still under debate. The presence of more than two types of H2O (type I and type II) in the structural channels of beryl is also unclear. This article aims to give an overview on the consensus and on the current debates found in the literature regarding these aspects. It mainly concentrates on the substitution by and the role of Fe ions and on channel occupancy by H2O.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366006","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}
Catherine Leyx, Peter Schmid-Beurmann, Fabrice Brunet, Christian Chopin, Christian Lathe
Abstract. The ambient-temperature compressibility and room-pressure thermal expansion of two Mg3(PO4)2 polymorphs (farringtonite = Mg3(PO4)2-I, with 5- and 6-fold coordinated Mg, and chopinite = “Mg-sarcopside” = [6]Mg3(PO4)2-II), three Mg2PO4OH polymorphs (althausite, hydroxylwagnerite and ε-Mg2PO4OH, all with [5]Mg and [6]Mg) and phosphoellenbergerite ([6]Mg) were measured on synthetic powders using a synchrotron-based multi-anvil apparatus to 5.5 GPa and a laboratory high-temperature diffractometer, with whole-pattern fitting procedures. Bulk moduli range from 64.5 GPa for althausite to 88.4 GPa for hydroxylwagnerite, the high-pressure Mg2PO4OH polymorph. Chopinite, based on an olivine structure with ordered octahedral vacancies (K0 = 81.6 GPa), and phosphoellenbergerite, composed of chains of face-sharing octahedra (K0 = 86.4 GPa), are distinctly more compressible than their homeotypical silicate (127 and 133 GPa, respectively). The compressibility anisotropy is the highest for chopinite and the lowest for phosphoellenbergerite. First-order parameters of quadratic thermal expansions range from v1 = 2.19×10-5 K−1 for ε-Mg2PO4OH to v1 = 3.58×10-5 K−1 for althausite. Phosphates have higher thermal-expansion coefficients than the homeotypical silicates. Thermal anisotropy is the highest for farringtonite and the lowest for hydroxylwagnerite and chopinite. These results set the stage for a thermodynamic handling of phase-equilibrium data obtained up to 3 GPa and 1000 °C in the MgO–P2O5–H2O and MgO–Al2O3–P2O5–H2O systems.
{"title":"Compressibility and thermal expansion of magnesium phosphates","authors":"Catherine Leyx, Peter Schmid-Beurmann, Fabrice Brunet, Christian Chopin, Christian Lathe","doi":"10.5194/ejm-36-417-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-417-2024","url":null,"abstract":"Abstract. The ambient-temperature compressibility and room-pressure thermal expansion of two Mg3(PO4)2 polymorphs (farringtonite = Mg3(PO4)2-I, with 5- and 6-fold coordinated Mg, and chopinite = “Mg-sarcopside” = [6]Mg3(PO4)2-II), three Mg2PO4OH polymorphs (althausite, hydroxylwagnerite and ε-Mg2PO4OH, all with [5]Mg and [6]Mg) and phosphoellenbergerite ([6]Mg) were measured on synthetic powders using a synchrotron-based multi-anvil apparatus to 5.5 GPa and a laboratory high-temperature diffractometer, with whole-pattern fitting procedures. Bulk moduli range from 64.5 GPa for althausite to 88.4 GPa for hydroxylwagnerite, the high-pressure Mg2PO4OH polymorph. Chopinite, based on an olivine structure with ordered octahedral vacancies (K0 = 81.6 GPa), and phosphoellenbergerite, composed of chains of face-sharing octahedra (K0 = 86.4 GPa), are distinctly more compressible than their homeotypical silicate (127 and 133 GPa, respectively). The compressibility anisotropy is the highest for chopinite and the lowest for phosphoellenbergerite. First-order parameters of quadratic thermal expansions range from v1 = 2.19×10-5 K−1 for ε-Mg2PO4OH to v1 = 3.58×10-5 K−1 for althausite. Phosphates have higher thermal-expansion coefficients than the homeotypical silicates. Thermal anisotropy is the highest for farringtonite and the lowest for hydroxylwagnerite and chopinite. These results set the stage for a thermodynamic handling of phase-equilibrium data obtained up to 3 GPa and 1000 °C in the MgO–P2O5–H2O and MgO–Al2O3–P2O5–H2O systems.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140961972","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. Solid inclusion piezobarometry is the determination of the entrapment conditions of solid inclusions in a host by measurement and interpretation of the residual pressure of the inclusion. The development over the past two centuries of the concepts, analytical tools and measurement techniques of inclusion piezobarometry is reviewed, and potential future developments are outlined for the special issue of the European Journal of Mineralogy devoted to the study of mineral and melt inclusions.
{"title":"A brief history of solid inclusion piezobarometry","authors":"Ross J. Angel, Matteo Alvaro, Silvio Ferrero","doi":"10.5194/ejm-36-411-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-411-2024","url":null,"abstract":"Abstract. Solid inclusion piezobarometry is the determination of the entrapment conditions of solid inclusions in a host by measurement and interpretation of the residual pressure of the inclusion. The development over the past two centuries of the concepts, analytical tools and measurement techniques of inclusion piezobarometry is reviewed, and potential future developments are outlined for the special issue of the European Journal of Mineralogy devoted to the study of mineral and melt inclusions.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140963568","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}
F. Caso, A. Petroccia, S. Nerone, Andrea Maffeis, A. Corno, Michele Zucali
Abstract. Despite the fact that rock textures depend on the 3D spatial distribution of minerals, our tectono-metamorphic reconstructions are mostly based on a 2D visualisation (i.e. thin sections). This work compares 2D and 3D investigations of petrography and microstructures, modal abundances, and local bulk rock composition and their implication for P–T estimates, showing the pros and cons and reliability of 2D analysis. For this purpose, a chloritoid–garnet-bearing mica schist from the Dora-Maira Massif in the Western Alps has been chosen. In particular, for 2D a thin section scan has been combined with chemical X-ray maps, whereas for 3D the X-ray computerised axial microtomography (µCT) has been applied. Two-dimensional investigations are readily accessible and straightforward but do not consider the entire rock volume features. Conversely, the rise of 3D techniques offers a more comprehensive and realistic representation of metamorphic features in the 3D space. However, they are computationally intensive, requiring specialised tools and expertise. The choice between these approaches should be based on the research aims, available resources, and the level of detail needed to address specific scientific questions. Nevertheless, despite differences in the modal distribution, the estimated bulk rock compositions and relative thermodynamic modelled phase fields show similarities when comparing the 2D and 3D results. Also, since different thin section cut orientations may influence the results and consequent interpretations, three different cuts from the 3D model have been extrapolated and discussed (i.e. XZ, YZ, and XY planes of the finite-strain ellipsoid). This study quantitatively corroborates the reliability of the thin section approach for tectono-metamorphic reconstructions, still emphasising that 3D visualisation can help understand rock textures.
摘要尽管岩石纹理取决于矿物的三维空间分布，但我们的构造-变质重建大多基于二维可视化（即薄切片）。这项工作比较了岩相学和微观结构、模态丰度和局部块体岩石成分的二维和三维研究及其对 P-T 估计的影响，显示了二维分析的利弊和可靠性。为此，我们选择了西阿尔卑斯山多拉-迈拉地块的含绿泥石-石榴石的云母片岩。其中，二维分析采用了薄片扫描与化学 X 射线图相结合的方法，而三维分析则采用了 X 射线计算机轴向微层析成像 (µCT)。二维勘测方便、直接，但无法考虑整个岩体的特征。相反，三维技术的兴起则能更全面、更真实地反映三维空间的变质特征。然而，这些方法计算量大，需要专门的工具和专业知识。应根据研究目的、可用资源以及解决具体科学问题所需的详细程度来选择这些方法。不过，尽管模态分布存在差异，但在比较二维和三维结果时，估计的岩体成分和相对热力学模型相场显示出相似性。此外，由于不同的薄片切割方向可能会影响结果和相应的解释，因此对三维模型的三种不同切割方向（即有限应变椭球体的 XZ、YZ 和 XY 平面）进行了推断和讨论。这项研究从数量上证实了薄片方法在构造-变质重建中的可靠性，同时也强调了三维可视化有助于理解岩石纹理。
{"title":"Comparison between 2D and 3D microstructures and implications for metamorphic constraints using a chloritoid–garnet-bearing mica schist","authors":"F. Caso, A. Petroccia, S. Nerone, Andrea Maffeis, A. Corno, Michele Zucali","doi":"10.5194/ejm-36-381-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-381-2024","url":null,"abstract":"Abstract. Despite the fact that rock textures depend on the 3D spatial distribution of minerals, our tectono-metamorphic reconstructions are mostly based on a 2D visualisation (i.e. thin sections). This work compares 2D and 3D investigations of petrography and microstructures, modal abundances, and local bulk rock composition and their implication for P–T estimates, showing the pros and cons and reliability of 2D analysis. For this purpose, a chloritoid–garnet-bearing mica schist from the Dora-Maira Massif in the Western Alps has been chosen. In particular, for 2D a thin section scan has been combined with chemical X-ray maps, whereas for 3D the X-ray computerised axial microtomography (µCT) has been applied. Two-dimensional investigations are readily accessible and straightforward but do not consider the entire rock volume features. Conversely, the rise of 3D techniques offers a more comprehensive and realistic representation of metamorphic features in the 3D space. However, they are computationally intensive, requiring specialised tools and expertise. The choice between these approaches should be based on the research aims, available resources, and the level of detail needed to address specific scientific questions. Nevertheless, despite differences in the modal distribution, the estimated bulk rock compositions and relative thermodynamic modelled phase fields show similarities when comparing the 2D and 3D results. Also, since different thin section cut orientations may influence the results and consequent interpretations, three different cuts from the 3D model have been extrapolated and discussed (i.e. XZ, YZ, and XY planes of the finite-strain ellipsoid). This study quantitatively corroborates the reliability of the thin section approach for tectono-metamorphic reconstructions, still emphasising that 3D visualisation can help understand rock textures.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141016059","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}
Kai Qu, Xianzhang Sima, Xiangping Gu, Weizhi Sun, Guang Fan, Zeqiang Yang, Yanjuan Wang
Abstract. The new mineral kenoargentotetrahedrite-(Zn), [Ag6]4+(Cu4Zn2)Sb4S12□, was discovered at the Yindongpo Au deposit, Henan Province, China. It occurs as black metallic anhedral grains or equant crystals up to 40 µm in size. It is opaque in transmitted light and shows a greenish-grey colour in reflected light. Electron microprobe analysis for the studied material gave the empirical formula (on the basis of total cations being equal to 16 atoms per formula unit, apfu): M(2)(Ag3.75Cu2.25)Σ6M(1)[Cu3.90(Zn1.18Fe0.69Cd0.26)Σ2.13]Σ6.03X(3)(Sb3.69As0.27)Σ3.96S(1)S11.94 S(2)□. Kenoargentotetrahedrite-(Zn) is cubic, I4‾3m (no. 217), with a = 10.4624(4) Å, V= 1145.23(13) Å3, and Z= 2. The crystal structure has been refined to a final value of R1= 0.0247 on the basis of 274 independent reflections (Fo > 4σ (Fo)) by using single-crystal X-ray diffraction data. The seven strongest X-ray powder diffraction lines (d in Å (I) (hkl)) are the following: 3.010 (100) (222), 1.844 (30) (044), 2.606 (22) (004), 1.572 (15) (226), 2.046 (9) (134), 7.35 (6) (011), and 1.909 (5) (125). Kenoargentotetrahedrite-(Zn) is isostructural with other keno-member tetrahedrites with the [Ag6]4+ cluster. The structure refinement result confirms the coupling between the site occupancy factor of subvalent hexasilver clusters at the M(2) site and that of the vacancy at the S(2) site. This relationship further substantiates the charge balance substitution mechanism of S-deficiency tetrahedrites: 6M(2)Ag++S(2)S2-= M(2)[Ag6]4++S(2)□.
{"title":"Kenoargentotetrahedrite-(Zn), [Ag6]4+(Cu4Zn2)Sb4S12□, a new member of the tetrahedrite group from the Yindongpo Au deposit, China","authors":"Kai Qu, Xianzhang Sima, Xiangping Gu, Weizhi Sun, Guang Fan, Zeqiang Yang, Yanjuan Wang","doi":"10.5194/ejm-36-397-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-397-2024","url":null,"abstract":"Abstract. The new mineral kenoargentotetrahedrite-(Zn), [Ag6]4+(Cu4Zn2)Sb4S12□, was discovered at the Yindongpo Au deposit, Henan Province, China. It occurs as black metallic anhedral grains or equant crystals up to 40 µm in size. It is opaque in transmitted light and shows a greenish-grey colour in reflected light. Electron microprobe analysis for the studied material gave the empirical formula (on the basis of total cations being equal to 16 atoms per formula unit, apfu): M(2)(Ag3.75Cu2.25)Σ6M(1)[Cu3.90(Zn1.18Fe0.69Cd0.26)Σ2.13]Σ6.03X(3)(Sb3.69As0.27)Σ3.96S(1)S11.94 S(2)□. Kenoargentotetrahedrite-(Zn) is cubic, I4‾3m (no. 217), with a = 10.4624(4) Å, V= 1145.23(13) Å3, and Z= 2. The crystal structure has been refined to a final value of R1= 0.0247 on the basis of 274 independent reflections (Fo > 4σ (Fo)) by using single-crystal X-ray diffraction data. The seven strongest X-ray powder diffraction lines (d in Å (I) (hkl)) are the following: 3.010 (100) (222), 1.844 (30) (044), 2.606 (22) (004), 1.572 (15) (226), 2.046 (9) (134), 7.35 (6) (011), and 1.909 (5) (125). Kenoargentotetrahedrite-(Zn) is isostructural with other keno-member tetrahedrites with the [Ag6]4+ cluster. The structure refinement result confirms the coupling between the site occupancy factor of subvalent hexasilver clusters at the M(2) site and that of the vacancy at the S(2) site. This relationship further substantiates the charge balance substitution mechanism of S-deficiency tetrahedrites: 6M(2)Ag++S(2)S2-= M(2)[Ag6]4++S(2)□.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141014961","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. Several geological processes such as crustal and mantle metasomatism, high-grade metamorphism, and the formation of ore deposits involve the exchange of halogens, especially chlorine, between silicate minerals and fluids. It is well established that the presence of octahedral iron is vital to the process of Cl incorporation into amphiboles. However, other compositional controls on Cl incorporation, such as the effect of TAl, ANa, AK, and A-site occupancy are not as well constrained. This study reports on the compositional and structural relationships amongst a suite of 25 synthetic calcium amphiboles with a diverse range of Cl contents (0–1.68 atoms per formula unit (apfu)). Most amphiboles were synthesized along the potassic-hastingsite–potassic-chloro-hastingsite join (KCa2(Fe4Fe3+)(Al2Si6)O22(OH,Cl)2). Additional work involved substitution of Na for K, variable Al content, and substitution of Mg for Fe2+ in the bulk composition to explore these compositional effects on Cl incorporation. The relationship between pressure and the Cl content of amphiboles was also explored over the pressure range 0.3–2.0 GPa. Otherwise, synthesis conditions were 700 °C and 0.3 GPa with fO2 near Ni–NiO. Iron (II) chloride was used as the source of Cl. Some experiments used variably concentrated FeCl2 brines (0–100 molal), while others were nominally anhydrous, containing only the water absorbed by the hygroscopic FeCl2. All amphiboles were characterized by Rietveld refinements of powder X-ray diffraction patterns, electron microprobe analysis, and Mössbauer spectroscopy, the latter to determine Fe3+ fraction. This study finds a positive relationship between pressure and the Cl content of the amphibole. Both Fe2+ and Fe3+ are positively correlated with Cl among amphiboles with variable Fe#, but the correlation is poor to nonexistent for Mg-free amphiboles. Results indicate that the substitution of CFe2+,3+ for CMg and CFe2+,3+ for CAl facilitate Cl incorporation, with the former having a larger effect. The A-site occupancy is positively correlated with Cl in all amphiboles except those synthesized in dilute FeCl2 brines (≤ 6 m), which are negatively correlated. No correlation is observed between the Cl content of the amphibole and either the species of A cation (K vs. Na) or TAl. The composition vs. unit cell parameter data were analyzed using multivariate linear regression to better understand the process of Cl incorporation and to predict the molar volume of endmember chloro-amphiboles. The regression indicates an expansion of 0.181 Å (0.99 %) and 0.048 Å (0.90 %) along the b and c edges respectively, a reduction in β by 0.76° (0.72 %), and a contraction of 0.060 Å (0.59 %) along a when fully substituting Cl for OH in potassic-hastingsite. The multivariate linear regression equations allow the prediction of molar volumes for select endmember chloro-amphiboles, such as potassic-chloro-hastingsite = 964.63 ± 1.29 Å3 or 290.5 ± 0.4 cm3 mol−1.
{"title":"Crystal chemistry and molar volume of potassic-chloro-hastingsite","authors":"Jared P. Matteucci, David M. Jenkins, M. Dyar","doi":"10.5194/ejm-36-247-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-247-2024","url":null,"abstract":"Abstract. Several geological processes such as crustal and mantle metasomatism, high-grade metamorphism, and the formation of ore deposits involve the exchange of halogens, especially chlorine, between silicate minerals and fluids. It is well established that the presence of octahedral iron is vital to the process of Cl incorporation into amphiboles. However, other compositional controls on Cl incorporation, such as the effect of TAl, ANa, AK, and A-site occupancy are not as well constrained. This study reports on the compositional and structural relationships amongst a suite of 25 synthetic calcium amphiboles with a diverse range of Cl contents (0–1.68 atoms per formula unit (apfu)). Most amphiboles were synthesized along the potassic-hastingsite–potassic-chloro-hastingsite join (KCa2(Fe4Fe3+)(Al2Si6)O22(OH,Cl)2). Additional work involved substitution of Na for K, variable Al content, and substitution of Mg for Fe2+ in the bulk composition to explore these compositional effects on Cl incorporation. The relationship between pressure and the Cl content of amphiboles was also explored over the pressure range 0.3–2.0 GPa. Otherwise, synthesis conditions were 700 °C and 0.3 GPa with fO2 near Ni–NiO. Iron (II) chloride was used as the source of Cl. Some experiments used variably concentrated FeCl2 brines (0–100 molal), while others were nominally anhydrous, containing only the water absorbed by the hygroscopic FeCl2. All amphiboles were characterized by Rietveld refinements of powder X-ray diffraction patterns, electron microprobe analysis, and Mössbauer spectroscopy, the latter to determine Fe3+ fraction. This study finds a positive relationship between pressure and the Cl content of the amphibole. Both Fe2+ and Fe3+ are positively correlated with Cl among amphiboles with variable Fe#, but the correlation is poor to nonexistent for Mg-free amphiboles. Results indicate that the substitution of CFe2+,3+ for CMg and CFe2+,3+ for CAl facilitate Cl incorporation, with the former having a larger effect. The A-site occupancy is positively correlated with Cl in all amphiboles except those synthesized in dilute FeCl2 brines (≤ 6 m), which are negatively correlated. No correlation is observed between the Cl content of the amphibole and either the species of A cation (K vs. Na) or TAl. The composition vs. unit cell parameter data were analyzed using multivariate linear regression to better understand the process of Cl incorporation and to predict the molar volume of endmember chloro-amphiboles. The regression indicates an expansion of 0.181 Å (0.99 %) and 0.048 Å (0.90 %) along the b and c edges respectively, a reduction in β by 0.76° (0.72 %), and a contraction of 0.060 Å (0.59 %) along a when fully substituting Cl for OH in potassic-hastingsite. The multivariate linear regression equations allow the prediction of molar volumes for select endmember chloro-amphiboles, such as potassic-chloro-hastingsite = 964.63 ± 1.29 Å3 or 290.5 ± 0.4 cm3 mol−1.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140088371","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}
Roman Botcharnikov, Max Wilke, J. Garrevoet, Maxim Portnyagin, Kevin Klimm, Stephan Buhre, S. Krasheninnikov, R. Almeev, Severine Moune, Gerald Falkenberg
Abstract. Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <100 µm3. The probed volume is restricted to that just beneath the surface of the exposed object. This protocol avoids contamination of the signal by the host material and minimizes self-absorption effects. This technique has been tested on a set of experimental glasses with a wide range of Fe3+ / ΣFe ratios. The method was applied to the analysis of natural melt inclusions trapped in forsteritic to fayalitic olivine crystals of the Hekla volcano, Iceland. Our measurements reveal changes in Fe3+ / ΣFe from 0.17 in basaltic up to 0.45 in dacitic melts, whereas the magnetite–ilmenite equilibrium shows redox conditions with Fe3+ / ΣFe ≤0.20 (close to FMQ, fayalite–magnetite–quartz redox equilibrium) along the entire range of Hekla melt compositions. This discrepancy indicates that the oxidized nature of glasses in the melt inclusions could be related to the post-entrapment process of diffusive hydrogen loss from inclusions and associated oxidation of Fe in the melt. The Fe3+ / ΣFe ratio in silicic melts is particularly susceptible to this process due to their low FeO content, and it should be critically evaluated before petrological interpretation.
{"title":"Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano","authors":"Roman Botcharnikov, Max Wilke, J. Garrevoet, Maxim Portnyagin, Kevin Klimm, Stephan Buhre, S. Krasheninnikov, R. Almeev, Severine Moune, Gerald Falkenberg","doi":"10.5194/ejm-36-195-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-195-2024","url":null,"abstract":"Abstract. Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <100 µm3. The probed volume is restricted to that just beneath the surface of the exposed object. This protocol avoids contamination of the signal by the host material and minimizes self-absorption effects. This technique has been tested on a set of experimental glasses with a wide range of Fe3+ / ΣFe ratios. The method was applied to the analysis of natural melt inclusions trapped in forsteritic to fayalitic olivine crystals of the Hekla volcano, Iceland. Our measurements reveal changes in Fe3+ / ΣFe from 0.17 in basaltic up to 0.45 in dacitic melts, whereas the magnetite–ilmenite equilibrium shows redox conditions with Fe3+ / ΣFe ≤0.20 (close to FMQ, fayalite–magnetite–quartz redox equilibrium) along the entire range of Hekla melt compositions. This discrepancy indicates that the oxidized nature of glasses in the melt inclusions could be related to the post-entrapment process of diffusive hydrogen loss from inclusions and associated oxidation of Fe in the melt. The Fe3+ / ΣFe ratio in silicic melts is particularly susceptible to this process due to their low FeO content, and it should be critically evaluated before petrological interpretation.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139784965","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}
Roman Botcharnikov, Max Wilke, J. Garrevoet, Maxim Portnyagin, Kevin Klimm, Stephan Buhre, S. Krasheninnikov, R. Almeev, Severine Moune, Gerald Falkenberg
Abstract. Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <100 µm3. The probed volume is restricted to that just beneath the surface of the exposed object. This protocol avoids contamination of the signal by the host material and minimizes self-absorption effects. This technique has been tested on a set of experimental glasses with a wide range of Fe3+ / ΣFe ratios. The method was applied to the analysis of natural melt inclusions trapped in forsteritic to fayalitic olivine crystals of the Hekla volcano, Iceland. Our measurements reveal changes in Fe3+ / ΣFe from 0.17 in basaltic up to 0.45 in dacitic melts, whereas the magnetite–ilmenite equilibrium shows redox conditions with Fe3+ / ΣFe ≤0.20 (close to FMQ, fayalite–magnetite–quartz redox equilibrium) along the entire range of Hekla melt compositions. This discrepancy indicates that the oxidized nature of glasses in the melt inclusions could be related to the post-entrapment process of diffusive hydrogen loss from inclusions and associated oxidation of Fe in the melt. The Fe3+ / ΣFe ratio in silicic melts is particularly susceptible to this process due to their low FeO content, and it should be critically evaluated before petrological interpretation.
{"title":"Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano","authors":"Roman Botcharnikov, Max Wilke, J. Garrevoet, Maxim Portnyagin, Kevin Klimm, Stephan Buhre, S. Krasheninnikov, R. Almeev, Severine Moune, Gerald Falkenberg","doi":"10.5194/ejm-36-195-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-195-2024","url":null,"abstract":"Abstract. Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <100 µm3. The probed volume is restricted to that just beneath the surface of the exposed object. This protocol avoids contamination of the signal by the host material and minimizes self-absorption effects. This technique has been tested on a set of experimental glasses with a wide range of Fe3+ / ΣFe ratios. The method was applied to the analysis of natural melt inclusions trapped in forsteritic to fayalitic olivine crystals of the Hekla volcano, Iceland. Our measurements reveal changes in Fe3+ / ΣFe from 0.17 in basaltic up to 0.45 in dacitic melts, whereas the magnetite–ilmenite equilibrium shows redox conditions with Fe3+ / ΣFe ≤0.20 (close to FMQ, fayalite–magnetite–quartz redox equilibrium) along the entire range of Hekla melt compositions. This discrepancy indicates that the oxidized nature of glasses in the melt inclusions could be related to the post-entrapment process of diffusive hydrogen loss from inclusions and associated oxidation of Fe in the melt. The Fe3+ / ΣFe ratio in silicic melts is particularly susceptible to this process due to their low FeO content, and it should be critically evaluated before petrological interpretation.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139845063","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}
I. Lykova, R. Rowe, G. Poirier, Henrik Friis, Kate Helwig
Abstract. The new mckelveyite group mineral bainbridgeite-(YCe), ideally Na2Ba2YCe(CO3)6 ⋅ 3H2O, was found at Mont Saint-Hilaire, Quebec, Canada. Bainbridgeite-(YCe) occurs as pseudotrigonal and pseudohexagonal hemimorphic crystals that show platy, columnar, tabular, cone-shaped, barrel-shaped, saucer-shaped, or spindle-shaped habit. They often form stacked or parallel growth aggregates, rosettes, and groups of radiating crystals. The crystals are usually less than 1 mm in size. Bainbridgeite-(YCe) varies in colour from pale yellow to yellow, grey to almost black, bluish grey, green-grey, or white. The streak is white; the lustre is vitreous. The mineral has no cleavage. The Mohs hardness is 3. Dcalc is 3.49 g cm−3. Bainbridgeite-(YCe) is optically biaxial (+), α= 1.572(2), β= 1.586(2), γ= 1.628(2), 2 V (calc.) = 62∘, 2 V (meas.) = 45(4)∘(589 nm). The IR spectrum is reported. The composition (wt %, average of five analyses) is Na2O 6.86, CaO 0.59, SrO 4.01, BaO 25.71, Y2O3 8.24, La2O3 4.96, Ce2O3 8.38, Pr2O3 0.48, Nd2O3 1.87, Sm2O3 0.23, Gd2O3 0.67, Tb2O3 0.07, Dy2O3 1.38, Ho2O3 0.32, Er2O3 0.94, Tm2O3 0.08, Yb2O3 0.49, CO2 27.03, H2O 5.67, total 97.98. The empirical formula of the holotype calculated on the basis of six cations is as follows: Na2.11Ca0.10Sr0.37Ba1.60Y0.70La0.29Ce0.49Pr0.03Nd0.11Sm0.01Gd0.03Dy0.07Ho0.02Er0.05 Yb0.02(CO3)5.86(H2O)3.00. The mineral is triclinic, P1, a= 9.1079(2) Å, b= 9.1066(3) Å, c= 6.9332(2) Å, α= 102.861(2)∘, β= 116.148(2)∘, γ= 60.181(2)∘, V= 447.85(2) Å3, and Z= 1. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are 6.22(42)(001, 1‾1‾1, 1‾01), 4.430(100)(01‾1, 2‾1‾1, 120), 4.094(37)(1‾2‾1, 1‾11, 210, 111), 3.263(26)(11‾1, 2‾1‾2, 121), 2.888(67)(1‾2‾2, 1‾12, 211), 2.633(38)(3‾01, 030, 3‾3‾1), 2.263(23)(2‾21, 2‾4‾1, 4‾2‾1). 2.010(20)(03‾2, 3‾3‾3, 3‾03, 301, 032, 331). The crystal structure, solved and refined from single-crystal X-ray diffraction data (R1= 0.040), is of the weloganite type.
{"title":"Mckelveyite group minerals – Part 3: Bainbridgeite-(YCe), Na2Ba2YCe(CO3)6 ⋅ 3H2O, a new species from Mont Saint-Hilaire, Canada","authors":"I. Lykova, R. Rowe, G. Poirier, Henrik Friis, Kate Helwig","doi":"10.5194/ejm-36-183-2024","DOIUrl":"https://doi.org/10.5194/ejm-36-183-2024","url":null,"abstract":"Abstract. The new mckelveyite group mineral bainbridgeite-(YCe), ideally Na2Ba2YCe(CO3)6 ⋅ 3H2O, was found at Mont Saint-Hilaire, Quebec, Canada. Bainbridgeite-(YCe) occurs as pseudotrigonal and pseudohexagonal hemimorphic crystals that show platy, columnar, tabular, cone-shaped, barrel-shaped, saucer-shaped, or spindle-shaped habit. They often form stacked or parallel growth aggregates, rosettes, and groups of radiating crystals. The crystals are usually less than 1 mm in size. Bainbridgeite-(YCe) varies in colour from pale yellow to yellow, grey to almost black, bluish grey, green-grey, or white. The streak is white; the lustre is vitreous. The mineral has no cleavage. The Mohs hardness is 3. Dcalc is 3.49 g cm−3. Bainbridgeite-(YCe) is optically biaxial (+), α= 1.572(2), β= 1.586(2), γ= 1.628(2), 2 V (calc.) = 62∘, 2 V (meas.) = 45(4)∘(589 nm). The IR spectrum is reported. The composition (wt %, average of five analyses) is Na2O 6.86, CaO 0.59, SrO 4.01, BaO 25.71, Y2O3 8.24, La2O3 4.96, Ce2O3 8.38, Pr2O3 0.48, Nd2O3 1.87, Sm2O3 0.23, Gd2O3 0.67, Tb2O3 0.07, Dy2O3 1.38, Ho2O3 0.32, Er2O3 0.94, Tm2O3 0.08, Yb2O3 0.49, CO2 27.03, H2O 5.67, total 97.98. The empirical formula of the holotype calculated on the basis of six cations is as follows: Na2.11Ca0.10Sr0.37Ba1.60Y0.70La0.29Ce0.49Pr0.03Nd0.11Sm0.01Gd0.03Dy0.07Ho0.02Er0.05 Yb0.02(CO3)5.86(H2O)3.00. The mineral is triclinic, P1, a= 9.1079(2) Å, b= 9.1066(3) Å, c= 6.9332(2) Å, α= 102.861(2)∘, β= 116.148(2)∘, γ= 60.181(2)∘, V= 447.85(2) Å3, and Z= 1. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are 6.22(42)(001, 1‾1‾1, 1‾01), 4.430(100)(01‾1, 2‾1‾1, 120), 4.094(37)(1‾2‾1, 1‾11, 210, 111), 3.263(26)(11‾1, 2‾1‾2, 121), 2.888(67)(1‾2‾2, 1‾12, 211), 2.633(38)(3‾01, 030, 3‾3‾1), 2.263(23)(2‾21, 2‾4‾1, 4‾2‾1). 2.010(20)(03‾2, 3‾3‾3, 3‾03, 301, 032, 331). The crystal structure, solved and refined from single-crystal X-ray diffraction data (R1= 0.040), is of the weloganite type.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139850440","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}
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