European Journal of Mineralogy最新文献

{"title":"IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) – Newsletter 75","authors":"Ferdinando Bosi, Frédéric Hatert, Marco Pasero, Stuart J. Mills","doi":"10.5194/ejm-35-891-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-891-2023","url":null,"abstract":"<jats:p>\u0000 </jats:p>","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135617614","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":"Vibrational properties of OH groups associated with divalent cations in corundum (<i>α</i>-Al₂O₃)","authors":"Michael C. Jollands, Shiyun Jin, Martial Curti, Maxime Guillaumet, Keevin Béneut, Paola Giura, Etienne Balan","doi":"10.5194/ejm-35-873-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-873-2023","url":null,"abstract":"Abstract. The infrared spectra of synthetic corundum (α-Al2O3) samples either doped directly with divalent cations (Mg2+) or containing divalent cations formed by reduction of trivalent cations in H2 gas (Co2+, Ni2+) may display broad OH stretching bands at ∼3000 cm−1 due to the structural incorporation of trace amounts of hydrogen. Experimental spectra recorded from some natural sapphires display a similar absorption band associated with a dominant absorption at 3161 cm−1, and some beryllium-diffused corundum crystals show a band at 3060 cm−1. All of these also display smaller and generally narrower bands between 1900 and 2700 cm−1, whose natures are poorly defined. In this work, the atomic-scale structure, relative stability and infrared spectroscopic properties of a series of OH defects in corundum (α-Al2O3) are theoretically investigated at the density-functional-theory level. The investigated defects consist of interstitial H+ ions forming OH groups and compensating for the charge imbalance related to the presence of divalent cations (Be2+, Mg2+, Cr2+, Mn2+, Fe2+, Co2+, Ni2+) substituted for Al3+ at nearby octahedral sites. Bands occurring at ∼3000 cm−1 in experimental spectra are assigned to the OH stretching modes of some of these defects, with bands observed around 1900 and 2700 cm−1 being assigned to overtones of corresponding OH bending modes. The results also support the assignment of the so-called “3161 cm−1 series”, observed in experimental spectra of some rubies and yellow sapphires, to structural OH groups in association with Fe2+ ions, rather than Si4+, as has been previously proposed. These inferences are also supported by analysis of correlations between band areas in experimental infrared spectra extracted from a database of corundum gemstones. A qualitative explanation relating the anomalous intensity and the polarisation properties of the OH bending overtone bands to the electrical anharmonicity of OH groups involved in medium-strength H bonds is proposed.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135730869","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":"Contrasting appinites, vaugnerites and related granitoids from the NW Iberian Massif: insight into mantle and crustal sources","authors":"Gumer Galán, Gloria Gallastegui, Andrés Cuesta, Guillermo Corretgé, Ofelia Suárez, Luis González-Menéndez","doi":"10.5194/ejm-35-845-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-845-2023","url":null,"abstract":"Abstract. Post-collisional Mg–K-rich mafic rocks with associated granitoids appear regularly in most orogens. They are relevant to evaluate the mantle role in the genesis of granitoids and thereby of the continental crust itself. The most characteristic Mg–K mafic rocks in the Variscan Iberian Massif are appinites and vaugnerites. Two examples with associated granitoids from NW Iberia have been compared to assess their mantle and crustal sources and the magmatic processes involved in their formation. Related granitoids are tonalites, granodiorites and monzonitic granites. Available whole-rock major and trace element compositions, as well as Sr and Nd isotopes, were used for this comparison, along with new Sr–Nd isotopic data. The appinite–granitoid association is calc–alkalic, whereas the vaugneritic one is calc–alkalic transitional to alkali–calcic. Vaugnerites are more enriched in Mg and K, compatible and incompatible trace elements and display more fractionated rare-earth element (REE) patterns than appinites. Associated granitoids provide similar differences. Appinites and vaugnerites have Sr and Nd crustal isotopic signatures resulting from partial melting of a different subduction-type metasomatised mantle: amphibole spinel lherzolites for appinites and more refractory and deeper amphibole phlogopite ± garnet peridotites for vaugnerites. Further interaction of these basic melts with coeval granitoids occurred during their ascent and emplacement. The monzonitic granites derived from partial melting of metaigneous acid granulites, without discarding contribution of metasediments and/or an increasing role of biotite incongruent melting in those related to vaugnerites. An assimilation with fractional crystallisation process between appinite magmas and granulites could explain tonalites and granodiorites. This process was not confirmed for granodiorites related to vaugnerites.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135884688","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":"Depth profile analyses by femtosecond laser ablation (multicollector) inductively coupled plasma mass spectrometry for resolving chemical and isotopic gradients in minerals","authors":"Martin Oeser, Ingo Horn, Ralf Dohmen, Stefan Weyer","doi":"10.5194/ejm-35-813-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-813-2023","url":null,"abstract":"Abstract. Femtosecond laser ablation (fs-LA) coupled to a multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) instrument has been proven to be a powerful means to analyze isotope ratios of “non-traditional” stable isotope systems with high spatial resolution, precision, and accuracy. The technique has been successfully applied, e.g., to investigate diffusion-generated isotopic zoning of the elements Li, Mg, and Fe in magmatic crystals. Here, we present a novel sampling technique employing a fs-LA system that is equipped with a computer numerical control (CNC) laser stage, using the open-source software LinuxCNC. Combining this laser set up with ICP-MS or MC-ICP-MS allows us to perform depth profile analyses of major and trace elements, respectively, as well as metal stable isotope variations of Fe and Mg in olivine crystals and in experimental diffusion couples. Samples are ablated in circular patterns with profile diameters of 100–200 µm using a laser spot size of 25–30 µm. Depending on the scan speed and the repetition rate of the laser, each ablated sample layer is between 300 nm and 3.0 µm thick. The integrated signal of one ablated layer represents one data point of the depth profile. We have tested this technique by analyzing 5–50 µm deep depth profiles (consisting of 15–25 individual layers) of homogeneous and chemically zoned olivine crystal cuboids. The minor and trace element analyses of the zoned cuboids, conducted by fs-LA-ICP-MS, were compared with “horizontal” profiles analyzed in polished sections of the cuboids with electron probe microanalysis (EPMA). Furthermore, we analyzed Fe–Mg isotopic depth profiles of the same cuboids with fs-LA-MC-ICP-MS, of which the chemically zoned ones also showed isotopic zoning at identical scales. Isotopic depth profiles were also conducted on an unzoned olivine cuboid that was coated with a 26Mg- and 56Fe-enriched olivine thin film (of ∼ 800 nm) in order to investigate top-to-bottom contamination during depth profiling. Our results indicate that (i) concentration data acquired by fs-LA depth profiling match well with EPMA data, (ii) precise and accurate Fe and Mg isotopic data can be obtained (i.e., precision and accuracy are ≤ 0.12 ‰ and ≤ 0.15 ‰ for both δ26Mg and δ56Fe, respectively), and (iii) potential top-to-bottom contamination during depth profiling of isotope ratios can be avoided. The technique presented herein is particularly suitable for the investigation of minerals or glasses with chemical and/or isotopic gradients (e.g., diffusion zoning) vertical to planar surfaces. It can also be applied in materials sciences in order to analyze thin films, coatings, or surface contaminations on solids.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135590397","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":"Very-low-grade phyllosilicates in the Aravis massif (Haute-Savoie, France) and the di-trioctahedral substitution in chlorite","authors":"Benoît Dubacq, Guillaume Bonnet, Manon Warembourg, Benoît Baptiste","doi":"10.5194/ejm-35-831-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-831-2023","url":null,"abstract":"Abstract. Very-low-grade mineral veins investigated in the impure limestone massif of the Aravis (Haute-Savoie, France) yielded a rich mineral assemblage typified by dolomite, calcite, quartz, illitic mica, fluorite and three types of chlorite. The vein network extends over more than 5 km and was probably emplaced around peak burial of the limestone (∼7 km depth, 190 ∘C). The mineralogy has been investigated with electron microscopy, mass spectrometry and X-ray diffraction, with emphasis on chlorite types. The first chlorite type is a chamosite often interlayered with illitic mica. The second type is a Mg-rich, Al-depleted cookeite. The third type is a Li-rich sudoite. Presence of the three chlorite types shows limited solubility between di-trioctahedral chlorite phase components (sudoite and cookeite) and with tri-trioctahedral chlorite (chamosite). Departure of the Li-rich sudoite and Mg-rich cookeite from the ideal end-member compositions suggests solid solutions towards a Li-sudoite component. The associated illitic mica does not contain Li in significant proportion but shows pyrophyllitic and di-trioctahedral substitution, without a Tschermak component. These results call for systematic studies of the Li content of chlorite and for better modelling of di-trioctahedral substitution in chlorite and mica.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135590344","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":"Regerite, KFe₆(PO₄)₄(OH)₇(H₂O)₆ ⋅ 4H₂O, the first new mineral species from the Kreuzberg pegmatite, Pleystein, Oberpfalz, Bavaria, Germany","authors":"Christian Rewitzer, Rupert Hochleitner, Ian E. Grey, Anthony R. Kampf, Stephanie Boer, Colin M. MacRae","doi":"10.5194/ejm-35-805-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-805-2023","url":null,"abstract":"Abstract. Regerite, KFe6(PO4)4(OH)7(H2O)6 ⋅ 4H2O, is the first new mineral species to be characterised from the Kreuzberg pegmatite, Pleystein, in the Oberpfalz, Bavaria. It was found in vugs on a specimen of drusy quartz, associated with rockbridgeite, strengite and phosphosiderite. Regerite occurs as clusters of yellowish-green prisms, typically 5 to 20 µm wide and up to 0.1 mm long. The crystals are flattened on {100} and elongated along [001], and they display the forms {100}, {010} and {011}. The measured density is 2.69(2) g cm−3. Optically, regerite crystals are biaxial (+), with α=1.670(5), β=1.690(5) and γ=1.730(5) (measured in white light), and 2V (meas) is 76(2)∘. The empirical formula from electron microprobe analyses and crystal structure refinement is K0.95(Fe5.663+Ti0.45)Σ6.11(PO4)3.95(OH)7[(H2O)5.33(OH)0.88]Σ6.21 ⋅ 4H2O. Regerite has monoclinic symmetry, with space group P21/c and unit-cell parameters a=15.408(11) Å, b=17.311(11) Å, c=9.870(11) Å, β=95.42(2)∘, V=2621(3) Å3 and Z=4. The crystal structure was refined using synchrotron single-crystal data to wRobs=0.065 for 6088 reflections with I&gt;3σ(I). The structure type has not been previously reported. It is made of heteropolyhedral layers parallel to {100} that consist of Fe-centred octahedra and PO4 tetrahedra. The layers are interconnected via edge-shared octahedral dimers to form slit-like channels along [001] that are occupied by K+ ions and water molecules.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135859935","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":"A revised model for activity–composition relations in solid and molten FePt alloys and a preliminary model for characterization of oxygen fugacity in high-pressure experiments","authors":"Marc M. Hirschmann, Hongluo L. Zhang","doi":"10.5194/ejm-35-789-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-789-2023","url":null,"abstract":"Abstract. We present new models for the activity of iron (γFe) in solid face-centered cubic (fcc) and liquid FePt alloy at high temperature and pressure to facilitate their use as sliding buffer redox sensors under extreme conditions. Numerous experimental studies of γFe in FePt alloy at 100 kPa have produced a wide spread of values. By favoring high-temperature studies that are more likely to have produced equilibrium measurement and excluding experiments for compositions and temperatures that probably encountered ordered or unmixed low-temperature phases, we regress an asymmetric Margules activity–composition model with parameters WFePtfcc=-121.5±2.1 kJ mol−1 and WPtFefcc=-93.3±4.3 kJ mol−1. These values are close to the widely used model of Kessel et al. (2001), but for Pt-rich compositions they predict larger Fe activities and correspondingly more reduced oxygen fugacities. Activity–composition relations in liquid FePt are calibrated from direct measurements of activities and, most sensitively, from the trace of the Fe–Pt liquidus. Together, these yield asymmetric Margules parameters of WFePtliq=-124.5 kJ mol−1 and WPtFeliq=-94.0 kJ mol−1. The effects of pressure on both fcc and liquid FePt alloy are considered from excess-volume relations. Both solid and liquid alloy display significant positive excess volumes of mixing. Extraction of the excess volume of mixing for fcc FePt alloy requires filtering data for ordered low-temperature phases and corrections for the effects of magnetostriction on Fe-rich compositions which exhibit “Invar” behavior. Applied at high temperatures and pressures, both solid and liquid FePt alloys have strongly negative deviations from ideality at low pressure, which become closer to ideal at high pressure. These models provide a provisional basis for the calculation of aFe in high-temperature, high-pressure experiments that, when combined with estimates of aFeO, allow characterization of fO2 under conditions relevant to magma oceans, core formation, and differentiation processes in the lower mantle of Earth or on other terrestrial planets. Improvements in these models require new constraints on the equation of state of FePt fcc alloy and documentation of the high-pressure melting relations in the system Fe–Pt.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136060612","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":"Metamorphic titanite–zircon pseudomorphs after igneous zirconolite","authors":"Cindy L. Urueña, Charlotte Möller, Anders Plan","doi":"10.5194/ejm-35-773-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-773-2023","url":null,"abstract":"Abstract. The formation of metamorphic zircon after baddeleyite is a well-known reaction that can be used to date the metamorphism of igneous silica-undersaturated rocks. By contrast, metamorphic minerals formed after igneous zirconolite have rarely been reported. In this paper, we document metamorphic titanite + zircon pseudomorphs formed from the metamorphic breakdown of igneous zirconolite in syenodiorite and syenite, in the southeastern Sveconorwegian Province, Sweden. Water-rich fluid influx during tectonometamorphism in epidote–amphibolite-facies metamorphic conditions caused the release of silica during a metamorphic reaction involving igneous feldspar and pyroxene and the simultaneous breakdown of igneous Zr-bearing phases. Typical titanite + zircon intergrowths are elongated or platy titanite crystals speckled with tiny inclusions of zircon. Most intergrowths are smaller than 15 µm; some are subrounded in shape. Locally, bead-like grains of titanite and zircon are intergrown with silicate minerals. The precursor igneous zirconolite was found preserved only in a sample of near-pristine igneous syenodiorite, as remnant grains of mainly < 2 µm in size. Two somewhat larger crystals, 8 and 12 µm, allowed semiquantitative confirmation using microprobe analysis. Analogous with zircon pseudomorphs after baddeleyite, titanite + zircon pseudomorphs after zirconolite potentially offer dating of the metamorphic reaction, although the small size of the crystals makes dating with today's techniques challenging. The scarcity of reports of zirconolite and pseudomorphs reflects that they are either rare or possibly overlooked.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135014456","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":"Genetic model for the color anomalies at the termination of pegmatitic gem tourmaline crystals from the island of Elba, Italy","authors":"Alessandra Altieri, Federico Pezzotta, Giovanni B. Andreozzi, Henrik Skogby, Ferdinando Bosi","doi":"10.5194/ejm-35-755-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-755-2023","url":null,"abstract":"Abstract. Tourmaline crystals from the island of Elba commonly display a sharp transition to dark colors at the analogous termination due to the incorporation of Fe and/or Mn during the latest stages of crystallization in pegmatites. The formation of such color anomalies is related to a dramatic physicochemical change in the crystallization environment as a consequence of an opening of the geochemical system. However, mechanisms that may lead to the availability of Fe and/or Mn in the residual cavity fluids have been unclear. On the basis of chemical and spectroscopic investigations, combined with structural and paragenetic observations of the cavities, we propose a general genetic model in which, as a consequence of a pocket rupture event, chemical alteration of Fe- and Mn-rich minerals that formed early in the pegmatitic rock surrounding the cavities occurred through leaching processes, produced by the action of the highly reactive late-stage cavity fluids. Such processes were responsible for the release of Fe and Mn in the geochemical system, allowing the formation of the late-stage dark-colored terminations in the tourmaline crystals. In some cavities, a high availability of Mn and/or Fe determined the evolution of the crystals from an initial elbaite/fluor-elbaite composition to celleriite, foitite or schorl. This compositional evolution trend can be described by the following general chemical substitution: XNa+ + Y(Li1.5 + Al0.5)3+ + WF− ↔ X□ + 2Y(Fe,Mn)2+ + WOH−.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135397079","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 effect of chemical variability and weathering on Raman spectra of enargite and fahlore","authors":"K. Berkh, J. Majzlan, J. Meima, Jakub Plášil, D. Rammlmair","doi":"10.5194/ejm-35-737-2023","DOIUrl":"https://doi.org/10.5194/ejm-35-737-2023","url":null,"abstract":"Abstract. Enargite (Cu3AsS4) and tennantite\u0000(Cu12As4S13) are typical As-bearing sulfides in intermediate-\u0000and high-sulfidation epithermal deposits. Trace and major element variations\u0000in enargite and tennantite and their substitution mechanisms are widely\u0000described. However, Raman spectra of the minerals with correlative\u0000quantitative chemical information are rarely documented, especially for\u0000enargite. Therefore, comparative electron and μ-Raman microprobe\u0000analyses were performed on enargite and fahlore grains. These spectra can be\u0000used in the industrial detection and subsequent removal of As-bearing sulfides\u0000prior to ore beneficiation in order to diminish the environmental impact of\u0000the metallurgical technologies. A simple Sb5+–As5+ substitution in enargite was confirmed by Raman\u0000analyses. Similarly, a complete solid solution series from tetrahedrite to\u0000tennantite (i.e., Sb3+–As3+ substitution) can be correlated with a\u0000gradual evolution in their Raman spectra. In turn, Te4+ occupies the\u0000As3+ and Sb3+ sites in fahlore by the coupled substitution\u0000Te4+ + Cu+ → (As, Sb)3+ + (Cu, Fe, Zn)2+.\u0000Accordingly, Raman bands of goldfieldite (Te-rich member) are strongly\u0000broadened compared with those of tetrahedrite and tennantite. A secondary phase with high porosity and a fibrous or wormlike texture was\u0000found in enargite in a weathered sample. The chemical composition, Raman\u0000spectrum, and X-ray diffraction signature of the secondary phase resemble\u0000tennantite. A gradual transformation of the primary enargite into this\u0000secondary phase was visualized by comparative electron and Raman microprobe\u0000mapping.","PeriodicalId":11971,"journal":{"name":"European Journal of Mineralogy","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48677034","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}