European Journal of Mineralogy最新文献

{"title":"Ferro-ferri-holmquistite, □Li2(Fe2+3Fe3+2)Si8O22(OH)2, Fe2+Fe3+ analogue of holmquistite, from the Iwagi islet, Ehime, Japan","authors":"M. Nagashima, T. Imaoka, T. Kano, J. Kimura, Q. Chang, Takashi Matsumoto","doi":"10.5194/ejm-34-425-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-425-2022","url":null,"abstract":"Abstract. Ferro-ferri-holmquistite (IMA2022-020), ideal formula\u0000□Li2(Fe32+Fe23+)Si8O22(OH)2, was\u0000found in albitized granite from the Iwagi islet, Ehime, Japan.\u0000Ferro-ferri-holmquistite is a CFe2+Fe3+ analogue of\u0000holmquistite and belongs to the lithium-subgroup amphiboles. It commonly\u0000occurs as acicular aggregate and/or isolated crystals in quartz, albite and\u0000K-feldspar and is blue with a bluish-grey streak and a vitreous luster. It\u0000has a Mohs hardness of 5 1/2. Its cleavage is perfect on\u0000{210}. Measured and calculated densities are\u0000Dmeas.=3.2 g cm−3 and Dcalc.=3.317 g cm−3,\u0000respectively. Ferro-ferri-holmquistite is optically biaxial (-), with\u0000α=1.685, β=1.713 and γ=1.727, and is\u0000pleochroic, with X= pale blue ∼ pale yellowish blue, Y= deep blue ∼ brownish blue and Z= deep blue ∼ deep bluish violet; X>Z>Y. The magnetic\u0000susceptibility is similar to the associated biotite.\u0000Ferro-ferri-holmquistite is insoluble in HCl, HNO3 and H2SO4.\u0000The empirical formula calculated on the basis of Σ(C+T) = 13 on the results obtained by electron\u0000microprobe analyzer (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is\u0000A(K0.01Na0.06)Σ0.07B(Li1.95Na0.04Ca0.01)Σ2.00C(Fe2.822+Fe1.393+Al0.51Mg0.22Mn0.052+Ti0.01)Σ5.00T(Si7.98Al0.02)Σ8.00O22(OH)1.94F0.06. Structure refinement converged\u0000to R1= 4.22 %. The space group is orthorhombic Pnma, and the\u0000unit-cell parameters are a= 18.5437(2) Å, b= 17.9222(1) Å, c= 5.3123(1) Å and V= 1765.51(1) Å3. Based on the refined\u0000site occupancies, the structural formula can be written as\u0000ANa0.062M4(Li1.952Na0.048)Σ2.000M1(Fe1.7702+Mg0.230)Σ2.000M2(Fe1.4463+Fe0.1022+Al0.452)Σ2.000M3(Fe0.8912+Mg0.109)Σ1.000TSi8O22(OH)2 (Z= 4). Three OH-stretching IR\u0000bands, centered at 3614, 3631 and 3644 cm−1, are assigned to the local\u0000configuration M1M1M3= FeFeFe, MgFeFe (including FeMgFe and FeFeMg) and\u0000MgMgFe (including MgFeMg and FeMgMg), respectively, based on the IR studies\u0000of the orthorhombic Pnma amphiboles.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43461737","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}

{"title":"Melting relations of Ca–Mg carbonates and trace element signature of carbonate melts up to 9 GPa – a proxy for melting of carbonated mantle lithologies","authors":"Melanie J. Sieber, M. Wilke, Oona Appelt, M. Oelze, M. Koch‐Müller","doi":"10.5194/ejm-34-411-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-411-2022","url":null,"abstract":"Abstract. The most profound consequences of the presence of Ca–Mg carbonates (CaCO3–MgCO3) in the Earth's upper mantle may be to lower the melting temperatures of the mantle and control the melt composition. Low-degree partial melting of a carbonate-bearing mantle produces CO2-rich, silica-poor melts compositionally imposed by the melting relations of carbonates. Thus, understanding the melting relations in the CaCO3–MgCO3 system facilitates the interpretation of natural carbonate-bearing silicate systems. We report the melting relations of the CaCO3–MgCO3 system and the partition coefficient of trace elements between carbonates and carbonate melt from experiments at high pressure (6 and 9 GPa) and temperature (1300–1800 ∘C) using a rocking multi-anvil press. In the absence of water, Ca–Mg carbonates are stable along geothermal gradients typical of subducting slabs. Ca–Mg carbonates (∼ Mg0.1–0.9Ca0.9–0.1CO3) partially melt beneath mid-ocean ridges and in plume settings. Ca–Mg carbonates melt incongruently, forming periclase crystals and carbonate melt between 4 and 9 GPa. Furthermore, we show that the rare earth element (REE) signature of Group-I kimberlites, namely strong REE fractionation and depletion of heavy REE relative to the primitive mantle, is resembled by carbonate melt in equilibrium with Ca-bearing magnesite and periclase at 6 and 9 GPa. This suggests that the dolomite–magnesite join of the CaCO3–MgCO3 system might be useful to approximate the REE signature of carbonate-rich melts parental to kimberlites.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49276286","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}

{"title":"The hierarchical internal structure of labradorite","authors":"Emilia Götz, H. Kleebe, U. Kolb","doi":"10.5194/ejm-34-393-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-393-2022","url":null,"abstract":"Abstract. The different structural features of labradorite and its\u0000incommensurate atomic structure have long been in the eye of science. In\u0000this transmission electron microscopy (TEM) study, all of the structural properties of labradorite could be\u0000investigated on a single crystal with an anorthite–albite–orthoclase\u0000composition of An53.4Ab41.5Or5.1. The various properties of\u0000labradorite could thus be visualized and connected to form a hierarchical\u0000structure. Both albite and pericline twins occur in the labradorite. The\u0000size of alternating Ca-rich and Ca-poor lamellae could be measured and linked to\u0000the composition and the color of labradorescence. Furthermore, a\u0000modulation vector of 0.0580(15)a* + 0.0453(33)b* − 0.1888(28)c* with a\u0000period of 3.23 nm was determined. The results indicate an eα\u0000labradorite structure, which was achieved by forming Ca-rich and Ca-poor\u0000lamellae. The average structure and subsequently the incommensurate crystal\u0000structure were solved with a three-dimensional electron diffraction (3DED)\u0000data set acquired with automated diffraction tomography (ADT) from a single\u0000lamella. The results are in good agreement with the structure solved by\u0000X-ray diffraction and demonstrate that 3DED–ADT is suitable for solving even\u0000incommensurate structures.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46279524","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}

{"title":"Tomsquarryite, NaMgAl3(PO4)2(OH)6 ● 8H2O, a new crandallite-derivative mineral from Tom's phosphate quarry, Kapunda, South Australia","authors":"P. Elliott, I. Grey, W. G. Mumme, C. MacRae, A. R. Kampf","doi":"10.5194/ejm-34-375-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-375-2022","url":null,"abstract":"Abstract. Tomsquarryite, NaMgAl3(PO4)2(OH)6 ⚫ 8H2O,\u0000is a new secondary phosphate mineral from Tom's phosphate quarry, Kapunda,\u0000South Australia. It occurs as colourless, talc-like hexagonal platelets,\u0000with diameters of a few tens of micrometres when formed from the\u0000decomposition of minyulite and as thicker (∼ 10 µm)\u0000hexagonal crystals when formed from alteration of gordonite. Associated\u0000minerals are penriceite, elliottite, minyulite, angastonite and wavellite.\u0000The calculated density is 2.22 g cm−3. Tomsquarryite crystals are\u0000uniaxial (+) with ω=1.490(3), ε=1.497(3)\u0000(white light). Dispersion was not observed. The partial orientation is Z≈c. Electron microprobe analyses of the holotype specimen give the\u0000empirical formula\u0000Na1.02K0.02Ca0.08Mg1.26Al2.86(PO4)2.00(OH)3.82F2.48 ⚫ 7.70H2O, based on 22 anions. Tomsquarryite belongs to the trigonal\u0000crystal system, space group R–3m, with hexagonal unit-cell parameters a=6.9865(5) Å, c=30.634(3) Å and V=1294.9(4) Å3 and with\u0000Z=3. The crystal structure was refined using single-crystal diffraction\u0000data; R1=0.069 for 303 reflections with I>2σ(I) to a\u0000resolution of 0.80 Å. The crystal structure is a derivative of the\u0000crandallite structure, with Ca2+ cations replaced by hydrated magnesium\u0000ions, [Mg(H2O)6]2+, resulting in an expansion of the\u0000interlayer separation from 5.4 Å in crandallite to 10.2 Å in\u0000tomsquarryite. The results for tomsquarryite are compared with those for the\u0000chemically and structurally related minerals penriceite and elliottite.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44006290","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}

{"title":"Graulichite-(La), LaFe³⁺₃(AsO₄)₂(OH)₆, a new addition to the alunite supergroup from the Patte d'Oie mine, Bou Skour mining district, Morocco","authors":"C. Biagioni, M. Ciriotti, G. Favreau, D. Mauro, F. Zaccarini","doi":"10.5194/ejm-34-365-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-365-2022","url":null,"abstract":"Abstract. The new mineral species graulichite-(La), ideally\u0000LaFe33+(AsO4)2(OH)6, has been discovered in the\u0000Patte d'Oie mine, Bou Skour mining district, Morocco. It occurs as yellow\u0000rhombohedral crystals, up to 0.1 mm in size, with a resinous luster,\u0000associated with malachite, agardite-(La), conichalcite, and a still\u0000undetermined REE carbonate. Crystals are chemically zoned and two\u0000homogeneous domains were identified, corresponding to the empirical chemical\u0000formulae (calculated on the basis of 6 cations per formula unit, assuming\u0000the occurrence of 14 O atoms)\u0000(La0.34Ce0.20Ca0.11Sr0.07Pb0.05K0.04)Σ0.81(Fe2.163+Al0.84Cu0.20)Σ3.20(As1.23P0.39S0.37)Σ1.99O14H6.13\u0000(domain #1) and\u0000(La0.38Ce0.22Sr0.10Ca0.09Pb0.05K0.06)Σ0.90(Fe2.603+Al0.49Cu0.20)Σ3.29(As0.91P0.50S0.40)Σ1.81O14H6.53\u0000(domain #2). Single-crystal unit-cell parameters are a=7.252(13), c=16.77(3) Å, V=764(3) Å3, space group R-3m. The eight strongest\u0000reflections in the observed X-ray powder diffraction pattern are (d in Å,\u0000visually estimated intensity): 5.86, medium; 3.045, strong; 2.511,\u0000medium-weak; 2.239, medium; 1.960, medium-weak; 1.813, medium-weak; 1.689,\u0000medium-weak; 1.478, medium. Graulichite-(La) belongs to the dussertite group\u0000within the alunite supergroup. It is the La analogue of graulichite-(Ce) and\u0000the Fe3+ analogue of arsenoflorencite-(La).\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45238238","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}

{"title":"High-pressure and high-temperature structure and equation of state of Na₃Ca₂La(CO₃)₅ burbankite","authors":"S. Milani, Deborah Spartà, P. Fumagalli, Boby Joseph, R. Borghes, V. Chenda, J. Maurice, G. Bais, M. Merlini","doi":"10.5194/ejm-34-351-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-351-2022","url":null,"abstract":"Abstract. In this study we report the synthesis of single crystals of\u0000burbankite, Na3Ca2La(CO3)5, at 5 GPa and 1073 K.\u0000The structural evolution, bulk modulus and thermal expansion of burbankite were\u0000studied and determined by two separate high-pressure (0–7.07(5) GPa) and\u0000high-temperature (298–746 K) in situ single-crystal X-ray diffraction\u0000experiments. The refined parameters of a second-order Birch–Murnaghan\u0000equation of state (EoS) are V0= 593.22(3) Å3 and KT0= 69.8(4) GPa. The thermal expansion coefficients of a Berman-type EoS are\u0000α0= 6.0(2) ×10-5 K−1, α1= 5.7(7) ×10-8 K−2 and V0= 591.95(8) Å3. The thermoelastic\u0000parameters determined in this study allow us to estimate the larger density\u0000of burbankite in the pressure-temperature range of 5.5–6 GPa and\u00001173–1273 K, with respect to the density of carbonatitic magmas at the same\u0000conditions. For this reason, we suggest that burbankite might fractionate\u0000from the magma and play a key role as an upper-mantle reservoir of light\u0000trivalent rare earth elements (REE3+).\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43604724","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}

{"title":"High-pressure homogenization of olivine-hosted CO₂-rich melt inclusions in a piston cylinder: insight into the volatile content of primary mantle melts","authors":"R. Buso, D. Laporte, F. Schiavi, N. Cluzel, Claire Fonquernie","doi":"10.5194/ejm-34-325-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-325-2022","url":null,"abstract":"Abstract. Experimental homogenization of olivine-hosted melt inclusions\u0000representative of near-primary basic and ultrabasic magmas is a powerful\u0000approach to investigate the nature of their source regions and the melting\u0000conditions in Earth's mantle. There is growing evidence that the total\u0000CO2 contents of olivine-hosted melt inclusions may reach values of the\u0000order of a single to several weight percent, especially in intraplate continental\u0000basalts. To be able to homogenize melt inclusions with such high CO2\u0000contents, we developed a technique allowing for heat treating of the melt\u0000inclusions under hydrostatic pressures up to 3–4 GPa in a piston cylinder,\u0000using thick-walled Au80–Pd20 containers and molten NaCl as\u0000the surrounding medium for the inclusion-bearing olivines. We applied this\u0000technique to olivine phenocrysts from Thueyts basanite, Bas-Vivarais\u0000volcanic province, French Massif Central. Thueyts melt inclusions were\u0000chosen because of their high CO2 contents, as indicated by up to\u00001.19 wt % dissolved CO2 in the glasses and by the presence of\u0000shrinkage bubbles containing abundant carbonate microcrystals in addition to\u0000a CO2 fluid phase. The homogenization experiments were conducted at\u0000pressures of 1.5 to 2.5 GPa, temperatures of 1275 and 1300 ∘C,\u0000and run durations of 30 min. In all the melt inclusions treated at 2.5 GPa–1300 ∘C and half of\u0000those treated at 2 GPa–1300 ∘C, we were able to completely\u0000homogenize the inclusions, as indicated by the disappearance of the starting\u0000bubbles, and we obtained total CO2 contents ranging from 3.2 wt % to\u00004.3 wt % (3.7 wt % on average). In all the other melt inclusions\u0000(equilibrated at 1.5 or 2 GPa and 1300 ∘C or at\u00002.5 GPa–1275 ∘C), we obtained lower and more variable total\u0000CO2 contents (1.4 wt % to 2.9 wt %). In the inclusions with the highest\u0000total CO2 contents, the size of the shrinkage bubble was in most cases\u0000small (<5 vol %) to medium (<10 vol %): this is a\u0000strong argument in favor of an origin of these melt inclusions by\u0000homogeneous entrapment of very CO2-rich basanitic liquids\u0000(∼ 4 wt %) at pressures of 2 to 2.5 GPa. The lower total\u0000CO2 contents measured in some inclusions could reflect a natural\u0000variability in the initial CO2 contents, due for instance to melt\u0000entrapment at different pressures, or CO2 loss by decrepitation. An\u0000alternative scenario is heterogeneous entrapment of basanitic liquid plus\u0000dense CO2 fluid at lower pressures but still at least on the order of\u00001 GPa as indicated by dissolved CO2 contents up to 1.19 wt % in the\u0000glasses of unheated melt inclusions. Whatever the scenario, the basanites\u0000from the Bas-Vivarais volcanic province were generated in a mantle\u0000environment extremely rich in carbon dioxide.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42282024","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}

{"title":"Firing and post-firing dynamics of Mg- and Ca-rich bricks used in the built heritage of the city of Padua (northeastern Italy)","authors":"E. Pérez-Monserrat, L. Maritan, G. Cultrone","doi":"10.5194/ejm-34-301-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-301-2022","url":null,"abstract":"Abstract. Diverse types of bricks from monuments in the city of\u0000Padua (northeastern Italy) were studied using a multi-analytical approach\u0000based on spectrophotometry, X-ray fluorescence (XRF), X-ray powder\u0000diffraction (XRPD), polarized-light optical microscopy (POM) and/or\u0000high-resolution scanning electron microscopy with coupled energy-dispersive X-ray spectroscopy (HRSEM-EDS). The most\u0000representative bricks were yellow or beige and in well-preserved condition.\u0000The results showed that they were made of Mg- and Ca-rich illitic clays,\u0000were fired at high temperatures (from 900 to over 950 ∘C), and\u0000achieved an incipient vitrification. Two main processes took place during\u0000firing: (i) the development of a Ca-aluminosilicate amorphous phase where\u0000very abundant pyroxene-type crystals were nucleated and (ii) the\u0000transformation of the pristine Mg-rich clayey grains into Mg-silicate\u0000mineral phases. The analyses suggest a firing dynamic within a highly\u0000reactive and supersaturated unstable system, particularly rich in calcium\u0000and magnesium. There are also signs of the rapid heating and/or soaking of\u0000the bricks and the irregular heat distribution and/or different residence\u0000times inside the kilns. The formation of zeolite and calcite secondary\u0000phases was also observed. The former was largely promoted by the high\u0000calcium content of the bodies and the very humid conditions, while the\u0000latter was mainly precipitated from Ca-rich solutions. The preservation of\u0000the bricks was enhanced by processes that took place both during and after\u0000firing. Firstly, the significant development of a Ca-rich amorphous phase\u0000and of high-temperature pyroxene-type crystals has provided strength to\u0000the bricks. Secondly, the porosity yielded by the firing of the\u0000carbonate-rich clays was almost filled by secondary calcite, which acted as\u0000a cementing agent. The information attained has increased the knowledge of\u0000(i) the mineralogical and microstructural changes that take place during the\u0000firing over 900 ∘C of Ca- and Mg-rich illitic clays and (ii) the\u0000formation of secondary phases within highly calcareous bricks laid in very\u0000humid environments and affected by Ca-rich solutions. The key role of the\u0000Ca- and Mg-rich raw clays and of the high firing temperatures, in producing\u0000high-quality bricks, and of the secondary calcite, which increased their\u0000durability, is highlighted. All these factors have contributed to the better\u0000preservation of the built heritage of the city.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43715078","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}

{"title":"Crystallographic orientation mapping of lizardite serpentinite by Raman spectroscopy","authors":"M. Tarling, M. Demurtas, Steven A. Smith, J. Rooney, M. Negrini, C. Viti, J. Petriglieri, K. Gordon","doi":"10.5194/ejm-34-285-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-285-2022","url":null,"abstract":"Abstract. The serpentine mineral lizardite displays strong Raman\u0000anisotropy in the OH-stretching region, resulting in significant wavenumber\u0000shifts (up to ca. 14.5 cm−1) that depend on the orientation of the\u0000impinging excitation laser relative to the crystallographic axes. We\u0000quantified the relationship between crystallographic orientation and Raman\u0000wavenumber using well-characterised samples of Monte Fico lizardite by\u0000applying Raman spectroscopy and electron backscatter diffraction (EBSD)\u0000mapping on thin sections of polycrystalline samples and grain mounts of\u0000selected single crystals, as well as by a spindle stage Raman study of an\u0000oriented cylinder drilled from a single crystal. We demonstrate that the\u0000main band in the OH-stretching region undergoes a systematic shift that\u0000depends on the inclination of the c-axis of the lizardite crystal. The data\u0000are used to derive an empirical relationship between the position of this\u0000main band and the c-axis inclination of a measured lizardite crystal: y=14.5cos 4 (0.013x+0.02)+(3670±1), where y is the\u0000inclination of the c-axis with respect to the normal vector (in degrees), and\u0000x is the main band position (wavenumber in cm −1) in the OH-stretching\u0000region. This new method provides a simple and cost-effective technique for\u0000measuring and quantifying the crystallographic orientation of\u0000lizardite-bearing serpentinite fault rocks, which can be difficult to\u0000achieve using EBSD alone. In addition to the samples used to determine the\u0000above empirical relationship, we demonstrate the applicability of the\u0000technique by mapping the orientations of lizardite in a more complex sample\u0000of deformed serpentinite from Elba Island, Italy.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49637707","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}

{"title":"Automatic element and mineral detection in thin sections using hyperspectral transmittance imaging microscopy (HyperTIM)","authors":"Helge L. C. Daempfling, Christian Mielke, N. Koellner, M. Lorenz, C. Rogass, U. Altenberger, D. Harlov, M. Knoper","doi":"10.5194/ejm-34-275-2022","DOIUrl":"https://doi.org/10.5194/ejm-34-275-2022","url":null,"abstract":"Abstract. In this study we present a novel method for the automatic\u0000detection of minerals and elements using hyperspectral transmittance imaging\u0000microscopy measurements of complete thin sections (HyperTIM). This is\u0000accomplished by using a hyperspectral camera system that operates in the\u0000visible and near-infrared (VNIR) range with a specifically designed sample\u0000holder, scanning setup, and a microscope lens. We utilize this method on a\u0000monazite ore thin section from Steenkampskraal (South Africa), which we\u0000analyzed for the rare earth element (REE)-bearing mineral monazite ((Ce,Nd,La)PO4), with high\u0000concentrations of Nd. The transmittance analyses with the hyperspectral VNIR\u0000camera can be used to identify REE minerals and Nd in thin sections. We\u0000propose a three-point band depth index, the Nd feature depth index (NdFD),\u0000and its related product the Nd band depth index (NdBDI), which enables\u0000automatic mineral detection and classification for the Nd-bearing monazites\u0000in thin sections. In combination with the average concentration of the\u0000relative Nd content, it permits a destruction-free, total concentration\u0000calculation for Nd across the entire thin section.\u0000","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2022-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41736793","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}