E. Balan, L. Paulatto, Qianyu Deng, K. Béneut, M. Guillaumet, B. Baptiste
Abstract. The near-infrared (NIR) spectra of hydrous minerals display absorption bands involving multiple excitations of vibrational modes. They usually involve OH stretching modes, but their interpretation is not straightforward due to the combined effects of bond anharmonicity and vibrational coupling. In the present study, the mid-infrared (MIR) and near-infrared spectra of well-ordered samples of trioctahedral layered hydrous minerals, talc, brucite and lizardite, have been measured on a spectral range extending from the fundamental vibrational modes to the second OH stretching overtones. The bands corresponding to molecular overtones are interpreted using an effective approach allowing us to infer the anharmonicity and coupling parameters controlling the OH stretching frequencies from spectroscopic data. They follow the usual relation between transition energy and quantum number of the excited state, which facilitates the comparison of NIR and MIR spectra. The results support the assignment of the main overtone bands to specific environments of OH groups and bring new constraints for the identification of the vibrational bands related to Fe and Al substitutions at octahedral sites in serpentines. The two-phonon absorption bands are theoretically analyzed at the density functional theory level by computing the absorption arising from the self-energy of the IR-active vibrational modes. The characteristics of the two-phonon OH stretching continuum between 7300 and 7400 cm−1 and of the combination bands between 4000 and 4800 cm−1 are related to the specificities of the one-phonon and two-phonon densities of states of the three minerals.
{"title":"Molecular overtones and two-phonon combination bands in the near-infrared spectra of talc, brucite and lizardite","authors":"E. Balan, L. Paulatto, Qianyu Deng, K. Béneut, M. Guillaumet, B. Baptiste","doi":"10.5194/ejm-34-627-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-627-2022","url":null,"abstract":"Abstract. The near-infrared (NIR) spectra of hydrous minerals display absorption bands\u0000involving multiple excitations of vibrational modes. They usually involve OH\u0000stretching modes, but their interpretation is not straightforward due to the\u0000combined effects of bond anharmonicity and vibrational coupling. In the\u0000present study, the mid-infrared (MIR) and near-infrared spectra of\u0000well-ordered samples of trioctahedral layered hydrous minerals, talc,\u0000brucite and lizardite, have been measured on a spectral range extending\u0000from the fundamental vibrational modes to the second OH stretching\u0000overtones. The bands corresponding to molecular overtones are interpreted\u0000using an effective approach allowing us to infer the anharmonicity and coupling\u0000parameters controlling the OH stretching frequencies from spectroscopic data.\u0000They follow the usual relation between transition energy and quantum number\u0000of the excited state, which facilitates the comparison of NIR and MIR\u0000spectra. The results support the assignment of the main overtone bands to\u0000specific environments of OH groups and bring new constraints for the\u0000identification of the vibrational bands related to Fe and Al substitutions\u0000at octahedral sites in serpentines. The two-phonon absorption bands are\u0000theoretically analyzed at the density functional theory level by computing\u0000the absorption arising from the self-energy of the IR-active vibrational\u0000modes. The characteristics of the two-phonon OH stretching continuum between\u00007300 and 7400 cm−1 and of the combination bands between 4000 and 4800 cm−1 are related to the specificities of the one-phonon and two-phonon\u0000densities of states of the three minerals.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46464872","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. The ferric iron content in hydrothermally altered ultrabasic rocks and their major minerals, serpentines and Mg-chlorites, is important for establishing the oxidation state budget from oceanic ridges to subduction zones, in carbonaceous chondrites, and for modeling phase equilibria. A compilation of literature Mössbauer spectroscopic data on serpentines and magnesian chlorites from high-pressure ophiolites yields much lower ferric-to-total-iron ratios (Fe3+ / Fetotal) than those obtained on similar samples by X-ray absorption near-edge spectroscopy (XANES), leading to contradictory estimates of the ferric iron budget of subduction zones. New Mössbauer analysis of antigorite and Mg-chlorite samples from suites of high-pressure ophiolitic terrains of various Phanerozoic ages confirms the low and homogeneous values previously obtained by this technique, while lizardite inherited from oceanic hydrothermal alteration is ferric iron rich. We argue that XANES values may be biased by photo-oxidation when samples have a high Mg content, which is the case for serpentines and chlorites from subduction zones. Photo-oxidation is less important in Fe-poor phyllosilicates of the mica and talc families and does not affect the Fe-rich serpentines (greenalite, cronstedtite) of meteorites or Fe-rich terrestrial phyllosilicates. Mössbauer Fe3+ / Fetotal ratios of serpentine confirm the occurrence of a major redox change at the lizardite–antigorite transition near 300–400 ∘C rather than at the dehydration of antigorite at 500–650 ∘C in serpentinites from high-pressure ophiolites.
{"title":"Iron oxidation state in serpentines and magnesian chlorites of subduction-related rocks","authors":"B. Reynard, C. Fellah, C. McCammon","doi":"10.5194/ejm-34-645-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-645-2022","url":null,"abstract":"Abstract. The ferric iron content in hydrothermally altered ultrabasic rocks and their major minerals, serpentines and Mg-chlorites, is important for establishing the oxidation state budget from oceanic ridges to subduction zones, in carbonaceous chondrites, and for modeling phase equilibria. A compilation of literature Mössbauer spectroscopic data on serpentines and magnesian chlorites from high-pressure ophiolites yields much lower ferric-to-total-iron ratios (Fe3+ / Fetotal) than those obtained on similar samples by X-ray absorption near-edge spectroscopy (XANES), leading to contradictory estimates of the ferric iron budget of subduction zones. New Mössbauer analysis of antigorite and Mg-chlorite samples from suites of high-pressure ophiolitic terrains of various Phanerozoic ages confirms the low and homogeneous values previously obtained by this technique, while lizardite inherited from oceanic hydrothermal alteration is ferric iron rich. We argue that XANES values may be biased by photo-oxidation when samples have a high Mg content, which is the case for serpentines and chlorites from subduction zones. Photo-oxidation is less important in Fe-poor phyllosilicates of the mica and talc families and does not affect the Fe-rich serpentines (greenalite, cronstedtite) of meteorites or Fe-rich terrestrial phyllosilicates. Mössbauer Fe3+ / Fetotal ratios of serpentine confirm the occurrence of a major redox change at the lizardite–antigorite transition near 300–400 ∘C rather than at the dehydration of antigorite at 500–650 ∘C in serpentinites from high-pressure ophiolites.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41365226","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}
Artur Engelhardt, J. Koepke, Chao Zhang, D. Garbe‐Schönberg, A. Jesus
Abstract. The Oman ophiolite (Samail massif, Sultanate of Oman) is the largest sub-aerial exposure of oceanic lithosphere on Earth and provides the opportunity to study the accretion and alteration of oceanic lithosphere formed under fast-spreading conditions. Drill hole GT3A (23∘06′50.7′′ N, 58∘12′42.2′′ E) of the ICDP (International Continental Scientific Drilling Program) Oman Drilling Project with a length of 400 m aimed at penetrating the dike–gabbro transition of the Samail ophiolite paleocrust in order to shed light on the role of the axial melt lens (AML) during accretion of the lower plutonic crust. AMLs beneath fast-spreading mid-ocean ridges are sandwiched between the sheeted dike complex and the uppermost gabbros and are believed to feed the upper crust and, at least partially, the underlying crystal mush. Typical gabbroic rocks from dike–gabbro transitions of fast-spreading systems are the so-called “varitextured gabbros”, often showing considerable variations in mineral mode, texture and grain size, which are regarded as the frozen fillings of axial melt lenses. Here, we present a detailed petrographic, microanalytical and bulk-chemical investigation of 36 mafic rocks from the drill hole GT3A, which represent mostly varitextured gabbros, revealing a complex formation with several evolution stages. Poikilitic domains formed first, corresponding to an early crystallization stage, where only plagioclase and clinopyroxene of more primitive composition crystallized. Later, domains of granular textures containing also interstitial amphibole and Fe–Ti oxide were formed. This stage is characterized by a magma evolution that underwent crystal fractionation established by lower temperatures due to more efficient hydrothermal cooling at the margin of the AML. A last stage is characterized by pervasive hydrothermal alteration, where all primary minerals have been altered under temperature conditions, varying from the magmatic regime down to greenschist facies. A highlight of this stage is amphiboles showing noticeable compositional zoning. The observation of peculiar microgranular domains, representing relics of stoped exogenic material from the sheeted dike complex, documents the upward migration of an AML in a replenishment event, forcing the AML to burn through previously altered sheeted dikes. This process is responsible for significant assimilation of hydrothermally altered components, indicated by a marked Cl enrichment in the outer zones of magmatic amphiboles. Petrological modeling involving gabbros and basalts revealed that the GT3A rock suite followed a fractional crystallization evolution trend, with a primitive MORB as parental melt with an estimated water content of 0.2 wt % to 0.8 wt %. The modeled liquid lines of descent suggest a magmatic evolution via fractional crystallization, where the basalts correspond to frozen liquids, while the gabbros, especially the more primitive ones, show a significant cumulate component.
{"title":"ICDP Oman Drilling Project: varitextured gabbros from the dike–gabbro transition within drill core GT3A","authors":"Artur Engelhardt, J. Koepke, Chao Zhang, D. Garbe‐Schönberg, A. Jesus","doi":"10.5194/ejm-34-603-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-603-2022","url":null,"abstract":"Abstract. The Oman ophiolite (Samail massif, Sultanate of Oman) is the\u0000largest sub-aerial exposure of oceanic lithosphere on Earth and provides the\u0000opportunity to study the accretion and alteration of oceanic lithosphere\u0000formed under fast-spreading conditions. Drill hole GT3A (23∘06′50.7′′ N, 58∘12′42.2′′ E) of the ICDP (International Continental\u0000Scientific Drilling Program) Oman Drilling Project with a length of 400 m\u0000aimed at penetrating the dike–gabbro transition of the Samail ophiolite\u0000paleocrust in order to shed light on the role of the axial melt lens (AML)\u0000during accretion of the lower plutonic crust. AMLs beneath fast-spreading\u0000mid-ocean ridges are sandwiched between the sheeted dike complex and the\u0000uppermost gabbros and are believed to feed the upper crust and, at least\u0000partially, the underlying crystal mush. Typical gabbroic rocks from dike–gabbro transitions of fast-spreading\u0000systems are the so-called “varitextured gabbros”, often showing\u0000considerable variations in mineral mode, texture and grain size, which are\u0000regarded as the frozen fillings of axial melt lenses. Here, we present a\u0000detailed petrographic, microanalytical and bulk-chemical investigation of 36\u0000mafic rocks from the drill hole GT3A, which represent mostly varitextured\u0000gabbros, revealing a complex formation with several evolution stages.\u0000Poikilitic domains formed first, corresponding to an early crystallization\u0000stage, where only plagioclase and clinopyroxene of more primitive\u0000composition crystallized. Later, domains of granular textures containing\u0000also interstitial amphibole and Fe–Ti oxide were formed. This stage is\u0000characterized by a magma evolution that underwent crystal fractionation\u0000established by lower temperatures due to more efficient hydrothermal\u0000cooling at the margin of the AML. A last stage is characterized by pervasive\u0000hydrothermal alteration, where all primary minerals have been altered under\u0000temperature conditions, varying from the magmatic regime down to greenschist\u0000facies. A highlight of this stage is amphiboles showing noticeable\u0000compositional zoning. The observation of peculiar microgranular domains,\u0000representing relics of stoped exogenic material from the sheeted dike\u0000complex, documents the upward migration of an AML in a replenishment event,\u0000forcing the AML to burn through previously altered sheeted dikes. This\u0000process is responsible for significant assimilation of hydrothermally\u0000altered components, indicated by a marked Cl enrichment in the outer zones\u0000of magmatic amphiboles. Petrological modeling involving gabbros and basalts\u0000revealed that the GT3A rock suite followed a fractional crystallization\u0000evolution trend, with a primitive MORB as parental melt with an estimated\u0000water content of 0.2 wt % to 0.8 wt %. The modeled liquid lines of descent\u0000suggest a magmatic evolution via fractional crystallization, where the\u0000basalts correspond to frozen liquids, while the gabbros, especially the more\u0000primitive ones, show a significant cumulate component.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41409302","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}
S. Aspiotis, J. Schlüter, G. Redhammer, B. Mihailova
Abstract. Raman spectroscopy combined with electron microprobe analysis as well as Mössbauer spectroscopy was applied to a series of 18 samples along the phlogopite (KMg3AlSi3O10(OH)2)–annite (KFe32+AlSi3O10(OH)2) join to establish a truly non-destructive method for crystallochemical characterization of biotite (A1M3T4O10X2, M3 = M1M2M2). The Raman scattering arising from the framework (15–1215 cm−1) and OH-stretching phonon modes (3000–3900 cm−1) was used to build up correlation trends between the Raman spectral features and crystal chemistry of biotite. We show that (a) the contents of MMg, MFe2+, and MFe3+ contents can be quantified with a relative error of ∼ 6 %, ∼ 6 %, and ∼ 8 %, respectively, by combining the integrated intensities of the OH-stretching peaks assigned to various M1M2M2 local configurations with the wavenumber of the MO6 vibrational mode near 190 cm−1; (b) the MTi content can be estimated from the peak position and FWHM (full width at half maximum) of the second strongest TO4-ring mode at ∼ 680 cm−1, with a precision of 22 %; (c) the content of TSi can be estimated from the position of the second peak related to TO4-ring vibrations near 650 cm−1; (d) for phlogopite the TAl content can indirectly be calculated by knowing the amount of TSi, whereas for annite it is hindered by the plausible presence of TFe3+; (e) the AK content can be quantified by the position of the peak generated by T-Ob-T bond-stretching-and-bending vibration at ∼ 730 cm−1; and (f) interlayer-deficient biotites and F-rich phlogopite can be identified via their unique OH-stretching Raman peaks around 3570 cm−1 and 3695 cm−1, respectively. Our results show a potential tool for non-destructive quantitative estimations of the major (Mg, Fe, Si, Al, K) and minor (Ti) elements of the crystal chemistry of the biotite mineral group by using a non-destructive technique such as Raman spectroscopy, although its sensitivity is generally lower than that of electron microprobe analysis and therefore cannot detect trace elements. This is fundamental within the framework of cultural heritage where samples cannot be powdered or disassembled.
{"title":"Non-destructive determination of the biotite crystal chemistry using Raman spectroscopy: how far we can go?","authors":"S. Aspiotis, J. Schlüter, G. Redhammer, B. Mihailova","doi":"10.5194/ejm-34-573-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-573-2022","url":null,"abstract":"Abstract. Raman spectroscopy combined with electron microprobe analysis as well as\u0000Mössbauer spectroscopy was applied to a series of 18 samples along the\u0000phlogopite (KMg3AlSi3O10(OH)2)–annite\u0000(KFe32+AlSi3O10(OH)2) join to establish a truly\u0000non-destructive method for crystallochemical characterization of biotite\u0000(A1M3T4O10X2, M3 = M1M2M2). The Raman\u0000scattering arising from the framework (15–1215 cm−1) and OH-stretching\u0000phonon modes (3000–3900 cm−1) was used to build up correlation trends\u0000between the Raman spectral features and crystal chemistry of biotite. We\u0000show that (a) the contents of MMg, MFe2+, and\u0000MFe3+ contents can be quantified with a relative error of\u0000∼ 6 %, ∼ 6 %, and ∼ 8 %,\u0000respectively, by combining the integrated intensities of the OH-stretching\u0000peaks assigned to various M1M2M2 local configurations with the wavenumber of\u0000the MO6 vibrational mode near 190 cm−1; (b) the MTi content\u0000can be estimated from the peak position and FWHM (full width at half maximum) of the second strongest\u0000TO4-ring mode at ∼ 680 cm−1, with a precision of\u000022 %; (c) the content of TSi can be estimated from the position of\u0000the second peak related to TO4-ring vibrations near 650 cm−1; (d) for phlogopite the TAl content can indirectly be calculated by knowing\u0000the amount of TSi, whereas for annite it is hindered by the plausible\u0000presence of TFe3+; (e) the AK content can be quantified by\u0000the position of the peak generated by T-Ob-T bond-stretching-and-bending vibration at ∼ 730 cm−1; and (f) interlayer-deficient biotites and F-rich phlogopite can be identified via\u0000their unique OH-stretching Raman peaks around 3570 cm−1 and 3695 cm−1, respectively. Our results show a potential tool for\u0000non-destructive quantitative estimations of the major (Mg, Fe, Si, Al, K)\u0000and minor (Ti) elements of the crystal chemistry of the biotite mineral\u0000group by using a non-destructive technique such as Raman spectroscopy,\u0000although its sensitivity is generally lower than that of electron microprobe\u0000analysis and therefore cannot detect trace elements. This is fundamental\u0000within the framework of cultural heritage where samples cannot be powdered\u0000or disassembled.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45109600","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}
N. Dubrovinskaia, Maria Messingschlager, L. Dubrovinsky
Abstract. Hydroromarchite is a mineral that so far has been found only in a few locations in the world and recognized as a common product of submarine corrosion of pewter artefacts. Here we report a new locality for this rare mineral found at the Saint James Church archaeological site in Creussen, Germany. There it appeared to be a product of weathering of a tin artefact (a tin button) buried in soil of the churchyard for about 300 years. The mineral, found in paragenesis with romarchite and cassiterite, was identified using single-crystal X-ray diffraction.
{"title":"Tin weathering experiment set by nature for 300 years: natural crystals of the anthropogenic mineral hydroromarchite from Creussen, Bavaria, Germany","authors":"N. Dubrovinskaia, Maria Messingschlager, L. Dubrovinsky","doi":"10.5194/ejm-34-563-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-563-2022","url":null,"abstract":"Abstract. Hydroromarchite is a mineral that so far has been found only in a\u0000few locations in the world and recognized as a common product of submarine\u0000corrosion of pewter artefacts. Here we report a new locality for this rare\u0000mineral found at the Saint James Church archaeological site in Creussen,\u0000Germany. There it appeared to be a product of weathering of a tin artefact\u0000(a tin button) buried in soil of the churchyard for about 300 years. The\u0000mineral, found in paragenesis with romarchite and cassiterite, was\u0000identified using single-crystal X-ray diffraction.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43518848","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}
L. Faccincani, V. Cerantola, F. Nestola, P. Nimis, L. Ziberna, L. Pasqualetto, A. Chumakov, J. Harris, M. Coltorti
Abstract. Thanks to the physical strength of diamonds and their relatively unreactive chemical nature, their mineral inclusions may remain exceptionally preserved from alteration processes and chemical exchanges with surrounding minerals, fluids and/or melts following diamond formation. Cr-bearing spinels are relatively common inclusions found in peridotitic diamonds and important oxybarometers providing information about the oxygen fugacity (fO2) of their source mantle rocks. Here, we investigated a magnesiochromite–olivine touching pair in a diamond from the Udachnaya kimberlite (Siberia) by in situ single-crystal X-ray diffraction and energy-domain synchrotron Mössbauer spectroscopy, aiming to constrain the physical–chemical conditions of diamond formation and to explore the redox state of this portion of the Siberian craton when the diamond was formed. The P–T–fO2 entrapment conditions of the inclusion pair, determined by thermo- and oxybarometric analyses, are ∼ 5.7(0.4) GPa and ∼ 1015(50) ∘C (although entrapment at higher T and re-equilibration during subsequent mantle storage are also possible) and fO2 near the enstatite–magnesite–olivine–diamond (EMOD) buffer. The determined fO2 is similar to, or slightly more oxidized than, those of xenoliths from Udachnaya, but whilst the xenoliths last equilibrated with the surrounding mantle just prior to their entrainment in the kimberlite at ∼ 360 Ma, the last equilibration of the inclusion pair is much older, occurring at 3.5–3.1, ∼ 2 or ∼ 1.8 Ga before final encapsulation in its host diamond. Hence, the similarity between xenoliths and inclusion fO2 values indicates that the modern redox state of this portion of the Siberian lithosphere was likely attained relatively early after its formation and may have persisted for billions of years after diamond formation, at least at the local scale. Moreover, the oxygen fugacity determination for the inclusion pair provides direct evidence of diamond formation near the EMOD buffer and is consistent with recent models suggesting relatively oxidized, water-rich CHO fluids as the most likely parents for lithospheric diamonds.
{"title":"Relatively oxidized conditions for diamond formation at Udachnaya (Siberia)","authors":"L. Faccincani, V. Cerantola, F. Nestola, P. Nimis, L. Ziberna, L. Pasqualetto, A. Chumakov, J. Harris, M. Coltorti","doi":"10.5194/ejm-34-549-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-549-2022","url":null,"abstract":"Abstract. Thanks to the physical strength of diamonds and their relatively unreactive\u0000chemical nature, their mineral inclusions may remain exceptionally preserved\u0000from alteration processes and chemical exchanges with surrounding minerals,\u0000fluids and/or melts following diamond formation. Cr-bearing spinels are\u0000relatively common inclusions found in peridotitic diamonds and important\u0000oxybarometers providing information about the oxygen fugacity (fO2)\u0000of their source mantle rocks. Here, we investigated a\u0000magnesiochromite–olivine touching pair in a diamond from the Udachnaya\u0000kimberlite (Siberia) by in situ single-crystal X-ray diffraction and\u0000energy-domain synchrotron Mössbauer spectroscopy, aiming to constrain\u0000the physical–chemical conditions of diamond formation and to explore the\u0000redox state of this portion of the Siberian craton when the diamond was\u0000formed. The P–T–fO2 entrapment conditions of the inclusion pair, determined\u0000by thermo- and oxybarometric analyses, are ∼ 5.7(0.4) GPa and ∼ 1015(50) ∘C (although entrapment at higher T\u0000and re-equilibration during subsequent mantle storage are also possible) and\u0000fO2 near the enstatite–magnesite–olivine–diamond (EMOD) buffer. The\u0000determined fO2 is similar to, or slightly more oxidized than, those\u0000of xenoliths from Udachnaya, but whilst the xenoliths last equilibrated with\u0000the surrounding mantle just prior to their entrainment in the kimberlite at\u0000∼ 360 Ma, the last equilibration of the inclusion pair is much\u0000older, occurring at 3.5–3.1, ∼ 2 or ∼ 1.8 Ga before final encapsulation in its host diamond. Hence, the similarity\u0000between xenoliths and inclusion fO2 values indicates that the modern redox\u0000state of this portion of the Siberian lithosphere was likely attained\u0000relatively early after its formation and may have persisted for billions of\u0000years after diamond formation, at least at the local scale. Moreover, the\u0000oxygen fugacity determination for the inclusion pair provides direct\u0000evidence of diamond formation near the EMOD buffer and is consistent with\u0000recent models suggesting relatively oxidized, water-rich CHO fluids as the\u0000most likely parents for lithospheric diamonds.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42867306","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}
Chengyang Sun, Taijin Lu, Mingyue He, Zhonghua Song, Yi Deng
Abstract. Birefringence in diamond is an optical phenomenon related to strain and various defects in crystal lattices. Despite extensive investigations being done to characterize and quantify it, there is still controversy about its origin in diamond lattices. Here we report the relationship between the distribution of birefringence patterns observed under cross-polarized light, strain features analyzed by Raman mapping, and the impurity characteristics revealed by Fourier transform infrared spectroscopy (FTIR) mapping in natural mixed-habit diamonds. It was deduced that the plastic deformation was enhanced with higher tensile residual stress, and nitrogen and VN3H defects were more enriched as a result of the temperature increase during crystallization, at growth bands showing straight birefringence patterns and the relative enrichment of graphite inclusions. These results provided solid data and insights for birefringence-related properties in diamond and correlated the occurrence of birefringence with diamond spectroscopic properties, which promoted the understanding of the formation of birefringence in natural diamonds and would be helpful for the synthesis of high-quality, birefringence-free diamonds.
{"title":"Corresponding relationship between characteristic birefringence, strain, and impurities in Zimbabwean mixed-habit diamonds revealed by mapping techniques","authors":"Chengyang Sun, Taijin Lu, Mingyue He, Zhonghua Song, Yi Deng","doi":"10.5194/ejm-34-539-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-539-2022","url":null,"abstract":"Abstract. Birefringence in diamond is an optical phenomenon related\u0000to strain and various defects in crystal lattices. Despite extensive\u0000investigations being done to characterize and quantify it, there is still\u0000controversy about its origin in diamond lattices. Here we report the\u0000relationship between the distribution of birefringence patterns observed\u0000under cross-polarized light, strain features analyzed by Raman mapping, and\u0000the impurity characteristics revealed by Fourier transform infrared spectroscopy (FTIR) mapping in natural mixed-habit\u0000diamonds. It was deduced that the plastic deformation was enhanced with\u0000higher tensile residual stress, and nitrogen and VN3H defects\u0000were more enriched as a result of the temperature increase during\u0000crystallization, at growth bands showing straight birefringence patterns and\u0000the relative enrichment of graphite inclusions. These results provided solid\u0000data and insights for birefringence-related properties in diamond and\u0000correlated the occurrence of birefringence with diamond spectroscopic\u0000properties, which promoted the understanding of the formation of\u0000birefringence in natural diamonds and would be helpful for the synthesis of\u0000high-quality, birefringence-free diamonds.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44781034","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. Many rock-forming chain and sheet silicate minerals, i.e., pyroxenes, amphiboles, micas, and clay minerals, are built from shared chemical building blocks known as T-O-T modules. Each module consists of two opposing chains of vertex-sharing silica tetrahedra (T), which vertically sandwich a ribbon of edge-sharing metal–oxygen octahedra (O) in a T-O-T configuration. These minerals are both abundant and diverse in the lithosphere because T-O-T modules are chemically versatile (incorporating common crustal elements, e.g., O, Si, Al, Fe, and Mg) and structurally versatile (varying as a function of module width and linkage type) over a wide range of chemical and physical conditions. Therefore, these minerals lie at the center of understanding geological processes. However, their diversity leads to the minerals developing complex, 3D crystal structures, which are challenging to communicate. Ball-and-stick models and computer visualization software are the current methods for communicating the crystal structures of minerals, but both methods have limitations in communicating the relationships between these complex crystal structures. Here, we investigate the applications of 3D printing in communicating modular mineralogy and crystal structures. The open-source TotBlocks project consists of 3D-printed, T-O-T interlocking bricks, based on ideal polyhedral representations of T and O modules, which are linked by hexagonal pegs and slots. Using TotBlocks, we explore the relationships between modular minerals within the biopyribole (biotite–pyroxene–amphibole) and palysepiole (palygorskite–sepiolite) series. The bricks can also be deconstructed into T and O layer modules to build other mineral structures such as the brucite, kaolinite–serpentine, and chlorite groups. Then, we use the T-O-T modules within these minerals to visually investigate trends in their properties, e.g., habit, cleavage angles, and symmetry/polytypism. In conclusion, the TotBlocks project provides an accessible, interactive, and versatile way to communicate the crystal structures of common rock-forming minerals.
{"title":"TotBlocks: exploring the relationships between modular rock-forming minerals with 3D-printed interlocking brick modules","authors":"Derek. D. V. Leung, Paige E. dePolo","doi":"10.5194/ejm-34-523-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-523-2022","url":null,"abstract":"Abstract. Many rock-forming chain and sheet silicate minerals,\u0000i.e., pyroxenes, amphiboles, micas, and clay minerals, are built from shared\u0000chemical building blocks known as T-O-T modules. Each module consists of two\u0000opposing chains of vertex-sharing silica tetrahedra (T), which vertically\u0000sandwich a ribbon of edge-sharing metal–oxygen octahedra (O) in a T-O-T\u0000configuration. These minerals are both abundant and diverse in the\u0000lithosphere because T-O-T modules are chemically versatile (incorporating\u0000common crustal elements, e.g., O, Si, Al, Fe, and Mg) and structurally\u0000versatile (varying as a function of module width and linkage type) over a\u0000wide range of chemical and physical conditions. Therefore, these minerals\u0000lie at the center of understanding geological processes. However, their\u0000diversity leads to the minerals developing complex, 3D\u0000crystal structures, which are challenging to communicate. Ball-and-stick\u0000models and computer visualization software are the current methods for\u0000communicating the crystal structures of minerals, but both methods have\u0000limitations in communicating the relationships between these complex crystal\u0000structures. Here, we investigate the applications of 3D printing in\u0000communicating modular mineralogy and crystal structures. The open-source\u0000TotBlocks project consists of 3D-printed, T-O-T interlocking bricks, based on\u0000ideal polyhedral representations of T and O modules, which are linked by\u0000hexagonal pegs and slots. Using TotBlocks, we explore the relationships\u0000between modular minerals within the biopyribole (biotite–pyroxene–amphibole)\u0000and palysepiole (palygorskite–sepiolite) series. The bricks can also be\u0000deconstructed into T and O layer modules to build other mineral structures\u0000such as the brucite, kaolinite–serpentine, and chlorite groups. Then, we use\u0000the T-O-T modules within these minerals to visually investigate trends in their\u0000properties, e.g., habit, cleavage angles, and symmetry/polytypism. In\u0000conclusion, the TotBlocks project provides an accessible, interactive, and\u0000versatile way to communicate the crystal structures of common rock-forming\u0000minerals.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42015358","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}
A. Loges, G. Scholz, N. de Sousa Amadeu, Jingjing Shao, D. Schultze, Jeremy Fuller, B. Paulus, F. Emmerling, T. Braun, T. John
Abstract. The mutual influence of F and OH groups in neighboring sites in topaz (Al2SiO4(F,OH)2) was investigated using magic angle spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy. The splitting of 19F and 1H NMR signals, as well as the OH Raman band, provides evidence for hydrogen bond formation within the crystal structure. Depending on whether a given OH group has another OH group or fluoride as its neighbor, two different hydrogen bond constellations may form: either OH⋯O⋯HO or F⋯H⋯O. The proton accepting oxygen was determined to be part of the SiO4 tetrahedron using 29Si MAS NMR. Comparison of the MAS NMR data between an OH-bearing and an OH-free topaz sample confirms that the 19F signal at −130 ppm stems from F− ions that take part in H⋯F bonds with a distance of ∼ 2.4 Å, whereas the main signal at −135 ppm belongs to fluoride ions with no immediate OH group neighbors. The Raman OH sub-band at 3644 cm−1 stems from OH groups neighboring other OH groups, whereas the sub-band at 3650 cm−1 stems from OH groups with fluoride neighbors, which are affected by H⋯F bridging. The integrated intensities of these two sub-bands do not conform to the expected ratios based on probabilistic calculations from the total OH concentration. This can be explained by (1) a difference in the polarizability of the OH bond between the different hydrogen bond constellations or (2) partial order or unmixing of F and OH, or a combination of both. This has implications for the quantitative interpretation of Raman data on OH bonds in general and their potential use as a probe for structural (dis-)order. No indication of tetrahedrally coordinated Al was found with 27Al MAS NMR, suggesting that the investigated samples likely have nearly ideal Al/Si ratios, making them potentially useful as high-density electron microprobe reference materials for Al and Si, as well as for F.
摘要利用魔角自旋核磁共振(MAS NMR)和拉曼光谱研究了黄玉(Al2SiO4(F,OH)2)中相邻位置F和OH基团的相互影响。19F和1H核磁共振信号的分裂，以及OH拉曼带，为晶体结构内形成氢键提供了证据。根据给定的OH基团是否有另一个OH基团或其邻居是否有氟化物，可能形成两个不同的氢键星座:OH⋯O⋯HO或F⋯H⋯O。用29Si MAS NMR测定了接受氧的质子是sio4四面体的一部分。比较含OH和不含OH的黄玉样品之间的MAS nmr数据证实，- 130 ppm时的19f信号来自参与h⋯F键的F离子，距离为~ 2.4 Å，而- 135 ppm时的主要信号属于氟离子，没有直接的OH基团邻居。3644 cm−1处的拉曼OH亚带来自与其他OH基团相邻的OH基团，而3650 cm−1处的拉曼OH亚带来自与氟相邻的OH基团，它们受到H⋯F桥接的影响。这两个子带的综合强度不符合基于总OH浓度的概率计算的期望。这可以用(1)不同氢键星座之间OH键极化率的差异或(2)F和OH的偏序分解，或两者的结合来解释。这对羟基键的拉曼数据的定量解释以及它们作为结构(无序)秩序探针的潜在用途具有重要意义。在27Al MAS NMR中没有发现四面体配位Al的迹象，这表明所研究的样品可能具有接近理想的Al/Si比率，这使得它们有可能成为Al和Si以及F的高密度电子显微探针参考材料。
{"title":"Studies on the local structure of the F ∕ OH site in topaz by magic angle spinning nuclear magnetic resonance and Raman spectroscopy","authors":"A. Loges, G. Scholz, N. de Sousa Amadeu, Jingjing Shao, D. Schultze, Jeremy Fuller, B. Paulus, F. Emmerling, T. Braun, T. John","doi":"10.5194/ejm-34-507-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-507-2022","url":null,"abstract":"Abstract. The mutual influence of F and OH groups in neighboring\u0000sites in topaz (Al2SiO4(F,OH)2) was investigated using magic\u0000angle spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy.\u0000The splitting of 19F and 1H NMR signals, as well as the OH Raman band,\u0000provides evidence for hydrogen bond formation within the crystal structure.\u0000Depending on whether a given OH group has another OH group or fluoride as\u0000its neighbor, two different hydrogen bond constellations may form: either\u0000OH⋯O⋯HO or F⋯H⋯O. The proton accepting oxygen was determined to be part of the\u0000SiO4 tetrahedron using 29Si MAS NMR. Comparison of the MAS NMR\u0000data between an OH-bearing and an OH-free topaz sample confirms that the\u000019F signal at −130 ppm stems from F− ions that take part in\u0000H⋯F bonds with a distance of\u0000∼ 2.4 Å, whereas the main signal at −135 ppm belongs to\u0000fluoride ions with no immediate OH group neighbors. The Raman OH sub-band at\u00003644 cm−1 stems from OH groups neighboring other OH groups, whereas the\u0000sub-band at 3650 cm−1 stems from OH groups with fluoride neighbors,\u0000which are affected by H⋯F bridging. The\u0000integrated intensities of these two sub-bands do not conform to the expected\u0000ratios based on probabilistic calculations from the total OH concentration.\u0000This can be explained by (1) a difference in the polarizability of the OH bond\u0000between the different hydrogen bond constellations or (2) partial order\u0000or unmixing of F and OH, or a combination of both. This has implications for\u0000the quantitative interpretation of Raman data on OH bonds in general and\u0000their potential use as a probe for structural (dis-)order. No indication of\u0000tetrahedrally coordinated Al was found with 27Al MAS NMR, suggesting\u0000that the investigated samples likely have nearly ideal Al/Si ratios, making\u0000them potentially useful as high-density electron microprobe reference\u0000materials for Al and Si, as well as for F.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43521681","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}
P. Haase, S. Kiefer, K. Pollok, P. Drahota, J. Majzlan
Abstract. The sulfidic waste dumps of the historical mining sites Giftkies and Kaňk (Czech Republic) have been exposed to a temperate climate over decades. This exposure generated low-pH conditions caused by metal sulfide decomposition. Tin sulfides of the stannite–kësterite series [Cu2(Fe,Zn)SnS4] are common Sn minerals in the ores at the investigated sites. They decompose under acidic and oxidizing conditions and form in situ secondary precipitates. Compositional analyses of primary and secondary minerals were collected by electron microprobe to track the environmental mobility of the released elements during weathering. Transmission electron microscopy revealed a diffusion-driven alteration of stannite to Sn-rich chalcopyrite and the precipitation of native copper and silver from stannite. In assemblages containing arsenopyrite, an in situ and amorphous Sn–Fe–As (SFA)-rich phase precipitated close to the Sn sulfide. The SFA precipitate contains very little sulfur, which was probably released to the aqueous phase as oxidized species, whereas small amounts of Cu and Zn were captured by the SFA. This precipitate is metastable and acts as a temporaneous sink for mobile elements (Cu, Zn) and elements derived from acid-soluble silicates and phosphates (Ca, Si, Al, and P). With advanced weathering, complex redox reactions result in the precipitation of magnetite as an oxidation product of the sulfidic material under oxidative conditions. The stable minerals goethite and cassiterite mark the end of the weathering sequence and crystallized from the amorphous SFA precipitate.
{"title":"Weathering of stannite–kësterite [Cu2(Fe,Zn)SnS4] and the environmental mobility of the released elements","authors":"P. Haase, S. Kiefer, K. Pollok, P. Drahota, J. Majzlan","doi":"10.5194/ejm-34-493-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-493-2022","url":null,"abstract":"Abstract. The sulfidic waste dumps of the historical mining sites Giftkies\u0000and Kaňk (Czech Republic) have been exposed to a temperate climate over\u0000decades. This exposure generated low-pH conditions caused by metal sulfide\u0000decomposition. Tin sulfides of the stannite–kësterite series\u0000[Cu2(Fe,Zn)SnS4] are common Sn minerals in the ores at the\u0000investigated sites. They decompose under acidic and oxidizing conditions and\u0000form in situ secondary precipitates. Compositional analyses of primary and\u0000secondary minerals were collected by electron microprobe to track the\u0000environmental mobility of the released elements during weathering.\u0000Transmission electron microscopy revealed a diffusion-driven alteration of\u0000stannite to Sn-rich chalcopyrite and the precipitation of native copper and\u0000silver from stannite. In assemblages containing arsenopyrite, an in situ and\u0000amorphous Sn–Fe–As (SFA)-rich phase precipitated close to the Sn sulfide.\u0000The SFA precipitate contains very little sulfur, which was probably released\u0000to the aqueous phase as oxidized species, whereas small amounts of Cu and Zn\u0000were captured by the SFA. This precipitate is metastable and acts as a\u0000temporaneous sink for mobile elements (Cu, Zn) and elements derived from\u0000acid-soluble silicates and phosphates (Ca, Si, Al, and P). With advanced\u0000weathering, complex redox reactions result in the precipitation of magnetite\u0000as an oxidation product of the sulfidic material under oxidative conditions.\u0000The stable minerals goethite and cassiterite mark the end of the weathering\u0000sequence and crystallized from the amorphous SFA precipitate.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45786610","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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