MnO Content Research Articles

Olivines and Their Melt Inclusions in Potassic Volcanic Rocks Record Mantle Heterogeneity beneath the Southern Tibet

Abstract Constraints on mantle heterogeneity are important for understanding geochemical differentiation and recycling in Earth’s interior. Alkali basalts are of particular interest in this context due to the clear signatures of recycled components that they yield. Previous studies have focused more on oceanic basalts than on continental mafic rocks because the chemical and isotopic characteristics of the latter are often modified by crustal contamination; however, high-forsterite olivine crystals and olivine-hosted melt inclusions may record the compositions of primitive melts before extensive crustal contamination, providing valuable insights into mantle heterogeneity. Here we report the results of high-precision major-, minor-, and trace-element and Pb isotope analyses of olivine phenocrysts and melt inclusions from the Sailipu potassic alkali basalts from southern Tibet, which constrain the mantle source of continental potassic alkali basalts. The minor- and trace-element compositions of the olivine phenocrysts (e.g. Ni and Ca contents and 100 × Mn/Fe, 10 000 × Zn/Fe, and Ni/Co ratios) suggest that the primary magmas were derived from a phlogopite-bearing pyroxenite source in which peridotite residues were also present. The low- and high-Li contents of the olivine phenocrysts suggest the recycling of continental crustal material in their mantle source. Comparing the major-element compositions (e.g. SiO2, TiO2, Al2O3, MnO, CaO, and Na2O contents), FCMS and FCKANTMS parameters, and pseudo-ternary projections of the primary Sailipu magmas with experimental data suggests that the primary magmas were partial melts of olivine-poor or carbonated olivine-poor lithologies with a small amount of peridotite residue. The negative Nb and Ta and positive Pb anomalies seen in primitive mantle-normalized trace-element patterns and the extremely low Nb/U ratios of the melt inclusions suggest that recycling of continental crust was the main process involved in enriching the mantle source of the Sailipu magmas. The heterogeneous Pb isotopic compositions of the melt inclusions (208Pb/206Pb = 2.089 – 2.158; 207Pb/206Pb = 0.851 – 0.858) are consistent with the presence of peridotite residue in this source. The subduction of Indian continental crust introduced enriched material (including carbonatites) into the mantle.

TWO STAGES OF THE CENOZOIC ALKALINE-BASALT VOLCANISM IN THE DARKHAD DEPRESSION (NORTHERN MONGOLIA) – GEOCHRONOLOGY, GEOCHEMISTRY, AND GEODYNAMIC CONSEQUENCES

The isotopic data showed that there are two stages distinguished in the Cenozoic history of the Darkhad depression volcanic activity, the Late Oligocene initial stage (~28.0–26.6 Ma) and the final Late Miocene – Early Pliocene stage (~5.8–4.2 Ma). It has been stated that the rocks of the initial stage are only represented by trachybasalts; however, among the final-stage basaltoids there are series of shield-volcano hawaite-basanite-phonotephrite rocks and compex trachybasaltic "valley" lava flows, the formation of which is the last stage in the territorial volcanic evolution. It has been shown that the initial-stage trachybasaltic andesites are characterized by their enrichment of TiO2, P2O5, Sr, Zn, Ga and low concentrations of Al2O3, MnO, CaO, Sc and HREE (La/Yb=27.2–30.2). Basaltoids of the final stage have a similar rare-element distribution and show an increase in the contents of TiO2, Al2O3, P2O5, LILE, HFSE, Th, U and in the degree of fractionation of REE (La/Yb from 12.2 to 20.9) towards the rocks alkalinity enhancement. Modeling of eclogite, pyroxenite and peridotite melting processes in the La/Yb – Sm/Yb system shows that trachybasaltic andesite melts could be formed at ~7–8 % melting of eclogitic matter or at ~10–11 % melting of Grt-containing pyroxenites, with trachybasalt formed at ~3 % melting of Grt-containing peridotites. The composition distribution of rocks in coordinates (Mg# – Fe/Mn) indicates that the parental magmas are the initial-stage trachybasaltic andesite magmas as well as the Early Pliocene trachybasaltic "valley" lava flows. Sr, Nd, Pb isotope characteristics of the Darkhad depression basaltoids show significant shift of isotopic ratios in time towards the relatively enriched mantle as compared with the depleted MORB mantle. The initial formation of trachybasaltic andesite melts occurred in the Late Oligicene at the pre-rift stage of the territory development involving metasomatized mantle matter, with the pyroxenite or eclogite component contained in the magma formation source. The origin of trachybasalt magmas of the final stage is associated with the processes of decompression melting of peridotites in a weakly metasomatized lithospheric mantle at the rift stage of the Darkhad structure development.

CO2‐Rich Rejuvenated Stage Lavas on Hawaiian Islands

AbstractSedimentary carbonates are sent to the deep mantle if they are not completely destroyed at subduction zones, and subducted carbonates may contribute to plume volcanism. To better constrain the role of recycled carbonates in Hawaiian volcanism, we report high‐precision olivine and whole‐rock geochemical compositions of shield and rejuvenated stage lavas from Kauai, Oahu and Maui Islands. The studied rejuvenated stage whole‐rocks have low SiO2 and high CaO concentrations, and are depleted in high field strength elements, such as, Nb and Zr, consistent with a role of carbonated melt. Rejuvenated stage olivines have Ni abundance lower than and CaO and MnO contents similar to those of shield stage at a given Fo. The calculated partition coefficients of Ca () and Mn () between olivine and shield melts are consistent with those of a dry melt system. However, the low and for rejuvenated lavas can only be explained by a volatile‐rich melt system. Based on the observed and in rejuvenated lavas, and considering the effect of H2O, our modeling calculation shows that rejuvenated primary magmas contain up to ∼10 wt% CO2, indicating a CO2‐rich mantle source. Using olivine‐spinel aluminum exchange thermometry, we show that the rejuvenated primary magma temperatures are similar to those of shield stage. We posit that the CO2‐rich rejuvenated stage lavas with lower olivine Ni than those of shield stage lavas were originated from melting of carbonated peridotites in the plume. The carbonated melts that metasomatized the peridotites were likely derived from subducted ancient carbonate‐bearing lithospheric mantle.

Interfacial Behaviour in Ferroalloys: The Influence of FeMn Slag Composition

The present study investigated the interfacial interaction between FeMn alloy and slags of different compositions and basicity from 0.4 to 1.2 in a sessile drop furnace. Interfacial tension between the FeMn alloy and the slags was measured, and the results were analyzed to assess the sensitivity of the applied methodology. The measurement of the interfacial tension was based on combining the results from experiments, multiphase flow simulations in OpenFOAM, equilibrium calculations in FactSage, and calculation of slag density and surface tension based on numerical models. The results demonstrate that the interfacial tension between the FeMn alloy and slag increases with the slag basicity. It was found that the addition of Al_{2}O_{3} to the slag with basicity of 0.8 and 1.2 increases the interfacial tension, while increasing MnO content from 30.0 to 45.0 wt pct does not have any statistically significant influence on the interfacial tension. EPMA analysis of slag and FeMn phases showed that slags at lower basicities and the FeMn alloy form a metal–slag emulsion due to the destabilization of the interface induced by chemical reactions, partial reduction of SiO_{2} in the slag and the mass transfer of Si across the metal–slag interface.

Effects of MnO on the smelting process of vanadium titanomagnetite pre-reduced pellets in an electric furnace

MnO is proven as an effective fluxing additive for high-temperature pyrometallurgy processes. The effects of MnO on the electric furnace smelting of vanadium titanomagnetite pre-reduced pellets were systematically studied in this study. The results indicated that MnO addition could reduce the titanium slag viscosity. The activities of titania and silica in the slag decreased with the increasing MnO content. The external views of slag-iron separation showed that the addition of MnO was beneficial for the separation of iron from the slag. The EPMA results indicated that the reduction degree of vanadium oxides was improved with the MnO additions of 1 wt% and 2 wt%, but mitigated with the further increase of MnO. Moreover, the reduction of titanium oxides was suppressed with the increasing MnO content. Finally, it was concluded that the suitable addition of MnO was 2 wt% under the present smelting conditions.

Viscosity and structure evolution of molten vanadium slag during carbothermic reduction process

In this study, the viscosity and structure evolution of molten vanadium slag at different stages during carbothermic reduction process were investigated through employing the rotating cylinder technique, Fourier transformation infrared (FTIR) and Raman spectroscopy. The results showed that both the viscosity and apparent activation energy of the slag continuously increased with the decrease of FeO and MnO contents, while decreased with the decrement of Cr2O3 and V2O3 contents. The mole fractions of Q2 and Q3 units in the silicate melt increased significantly due to the decrease in the concentration of free oxygen with the reduction of FeO and MnO, and the structural units transformed from prevalent Q0 and Q1 to Q2 and Q3 dominant, resulting in the fact that the trough depth of the [SiO4]-tetrahedral band was obviously enhanced and its center shifted to a higher wavenumber region in the FTIR spectroscopy. On the contrary, the reduction of Cr2O3 and V2O3 brought a gradual increasing Q0 and Q1 concentration and lower polymerization degree of molten slag, while the trough depth of the [SiO4]-tetrahedral band was weakened and its center shifted to a lower wavenumber region, which responded well to the viscosity variation of the slag.

Conversion of Mn2+ into Mn3+ in manganese ions doped KF-CaO-B2O3 glasses: Electrical and spectroscopic properties

Melt quenching technique is used to prepare the glasses composition (KF–CaO–B2O3) with different concentration of manganese oxide in the range of 0.1–0.4 wt %. Nature of the fabricated glasses is confirmed by X-ray diffraction analysis. All calculated stability factors from differential thermal analysis increases with increasing the content of MnO. Infrared spectral analysis provided the information that those glass samples exhibited some symmetrical as well as asymmetrical bands belong to the borate group. The absorption results show a shifting in the absorption band, which is corresponding to the exchange of Mn2+ into the Mn3+ ions. Electron paramagnetic resonance results are shown two signals, which is characterized by Mn2+ and Mn3+. The variation in the intensity of these signals is discovered an improvement into glass stability with increased MnO content. The dielectric analyses is presented with different parameters with the variation of frequency from 103 Hz to 105 Hz and temperature 20 °C–400 °C.

Mineralogy and geochemistry of Kliripan manganese ore deposit, Hargorejo Village, Kokap District, Kulonprogo Regency

This study discusses the mineralogy and geochemistry of manganese deposits in the Kliripan area, where manganese had been mined since the Dutch occupancy until the 1970s. Although mining has been discontinued since then, the demand for manganese has increased in various industries, prompting exploration to continue to meet this demand. We performed petrographic, XRD, and XRF analysis of the ore and wall rock samples. Jasper and grainstone from the Sentolo Formation are the two lithologies where manganese mineralization occurs. Manganese-bearing minerals include pyrolusite, manganite, rhodochrosite, and lithiophorite, while the gangue minerals consist of quartz, calcite, hematite, and clay minerals. We interpret that Jasper is a product of alteration and has MnO content as high as 5.02 wt.%. Meanwhile, the economic grade manganese ore in grainstone has an MnO content up to 48.51 wt.%. The elements Ce, Zr, Co+Ni+Cu, are important discriminants to determine the type of manganese deposit. The results showed that the diagenetic process in reductive water formed the manganese ores. Oxidation of divalent manganese ion formed pyrolusite and manganite. Rhodochrosite crystallized when dilute manganese solution reacts with CO2 from limestone diagenesis. We concluded that the Kliripan manganese ore deposit has both hydrothermal and diagenetic deposits.

Age, petrogenesis, and tectonic setting of granitic gneiss and amphibolite from the Weizigou gold deposit, Heilongjiang Province, NE China: Constraints from geochronology and geochemistry

The Weizigou gold deposit is located in the western Jiamusi Massif, Northeast China. Gold mineralization is hosted in the amphibolite, which intruded the granitic gneiss. Although the deposit shows similarities to iron-oxide–copper–gold deposits, the detailed ore-forming process remains uncertain. To determine the formation age, petrogenesis, and tectonic setting of the granitic gneiss and amphibolite, LA–ICP–MS zircon, titanite, and monazite UPb dating, whole-rock major- and trace-element analyses, and LA–ICP–MS in situ zircon Hf isotope analyses were conducted on samples from these rocks. The granitic gneiss yielded two age populations of 951–882 Ma, and ca. 500 Ma, with a monazite UPb concordia age of 501.5 ± 5.1 Ma. The amphibolite yielded a crystallization age of 292 Ma, consistent with the results for magmatic titanite UPb dating, and a metamorphic age of 272–258 Ma. The granitic gneiss contains typical aluminum-rich minerals, such as garnet and muscovite, mean SiO2 = 73.31 wt%, and molar ratio Al2O3/(CaO + K2O + Na2O) values of 1.02–1.07, indicating an S-type granite protolith. The amphibolite belongs to the tholeiitic basalt series and has low SiO2 and high MnO contents. These results, together with εHf(t) values and two-stage model ages ranging from −9.5 to 2.3 and − 0.3 to 5.7, and from 2010 to 1659 Ma and from 1331 to 947 Ma, respectively, allow us to infer that the parental magmas of the granitic gneiss and amphibolite were derived from the partial melting of Paleoproterozoic lower crust and the partial melting of metasomatized depleted mantle, respectively. The granitic gneiss is characterized by positive Th and Hf anomalies, and negative Nb, Ta, Sr and Ti anomalies, whereas the amphibolite is enriched in K, Rb, and depleted in Ba, Nb, Ti, and Zr. These geochemical features suggest that the S-type granite was formed in an active continental margin during the Neoproterozoic and underwent granulite-facies metamorphism during the early Paleozoic. The protolith of the amphibolite was gabbro that formed in an extensional setting (e.g., a backarc basin) associated with westward subduction of the Paleo-Pacific oceanic plate beneath the eastern Jiamusi Massif during the early Permian. The gold mineralization can most likely be attributed to contact metasomatic metamorphism of gabbro during the middle–late Permian.

Clean and efficient extraction of vanadium from vanadium slag: Effect of manganese on the phase composition and vanadium extraction process

Manganese in vanadium slag plays an important role in the clean and efficient extraction of vanadium, attributed to the effect of manganese content on the phase of vanadium slag and the synergistic effects between manganese and roasting additives during the roasting process. In this study, remelting and crystallization method were used to prepare vanadium slag with different MnO mass fractions. The aforementioned effects were examined using XRD, SEM, and roasting-leaching experiments. The results show that manganese in vanadium slag always occupies the lattice of iron and forms (Mn, Fe)(V, Cr)2O4 and (Fe, Mn)2SiO4. With the increasing MnO content, the diffraction peaks of both spinel and olivine shift to a small angle due to the lattice distortion. Moreover, the MnO content has a greater influence on olivine than on spinel. Mn2V2O7 and Ca2V2O7 are the main vanadates of blank roasting and calcification roasting using n(CaO)/n(V2O3) of 2, respectively. During calcification roasting with n(CaO)/n(V2O3) less than 2, calcium vanadate and manganese vanadate coexist in the roasted samples. During leaching, the vanadium leaching rate shows a completely opposite trend after blank roasting and calcification roasting using n(CaO)/n(V2O3) of 2 as the MnO content increases. By reducing the amount of the added calcium salt, the vanadium leaching rate increases slightly compared with that in the case of n(CaO)/n(V2O3) is 2.0, which fluctuates between 83% and 86%. Furthermore, around 30% of manganese in vanadium slag transforms the vanadium-bearing phase and is further transferred to the leaching solution when reducing the amount of calcium salt properly.

Dating and geochemistry of zircon and apatite from rhyolite at the UNESCO geosite Rupnica (Mt. Papuk, northern Croatia) and the relationship to the Sava Zone

The Rupnica geosite, a key locality of the UNESCO-protected Papuk Geopark in northern Croatia, is well-known for an excellent exposure of columnar jointing in volcanic rock. This rock is defined as an albite rhyolite that comprises almost pure albite phenocrysts within a fine-grained matrix composed of microphenocrysts of albite, quartz and devitrified volcanic glass. Primary accessory minerals are clinopyroxene, apatite, zircon and magnetite. Haematite, apatite and anatase were found as inclusions in zircon. The albite rhyolite is characterized by a highly siliceous, peraluminous, oxidized (ferroan), dry, alkali-calcic to alkalic composition, with low CaO, MgO, and MnO contents and high FeOT/(FeOT+MgO) ratios. Normalized trace element contents display positive anomalies of K, Pb, and Zr as well as negative anomalies of Nb, P, Ti, Ba and Eu, together with an enrichment of light rare-earth elements (REE) relative to heavy REE. Zircon from the rhyolite of Rupnica is characterized by ratios of Th/U=1.13 and Zr/Hf=55 and contents of HfO2=1.04 wt. % typical for an early-stage igneous zircon crystallized from a dry high-temperature magma in a deep magma chamber. Apatite REE patterns show enrichment of light REE over heavy REE and a pronounced Eu anomaly, typical for apatite from granitoids formed in an oxidizing environment. The magma is of A-type and was generated at high temperatures at 800–900 °C by partial melting of lower- to mid-crustal rocks. The age of the albite rhyolite of Rupnica is Late Cretaceous at 80.8±1.8 (2σ) Ma, according to U-Pb dating of zircon, coeval with geochemically similar igneous rocks of Mt. Požeška Gora and Mt. Kozara within the Sava Zone.

Mineralogical and geochemical studies of copper mineralization in the Paleozoic sedimentary section in southwestern Sinai, Egypt

The present study provides new insights into the distribution and characteristics of copper-bearing Paleozoic clastic-carbonate units, Araba and Um Bogma formations in southwestern Sinai, Egypt. Malachite, azurite, atacamite, chrysocolla, and cuprite occur as disseminations or stratiform, layer-parallel streaks, and lenticular bodies that are intercalated with vanadiferous sandstones in the middle unit of the Araba Formation. The vanadiferous sandstones are rich in mottramite, mimetite, duftite, beudantite, descloizite and vanadinite. The Um Bogma Formation is characterized by uncommon chalcanthite, antlerite, malachite, chrysocolla, covellite, and chalcocite in addition to traces of pyrite and barite. These ore minerals occur as acicular, fibrous, fracture-filling, disseminated, and pore-filling patches and are associated with Mn-minerals. Copper minerals form also thin laminae in the manganiferous and black organic-rich shales of the Um Bogma Formation.Copper and vanadium minerals are disseminated in the arkose, subarkose, sublitharenite, graywacke, shale, siltstone and dolostone members of the host formations. Elevated copper concentrations (up to 5.04 wt%) and vanadium (≤362.3 ppm) are associated with high CaO and MgO contents in the intergranular patches and discontinuous laminae. In the Um Bogma Formation, the mineralized layers show high contents of MnO (up to 84.27 wt%) and Fe2O3 (up to 72.1 wt%), Ba (0.03–2.86 wt%), S (up to 0.452 wt%) and Ni (0.012–0.041 wt%).Mineralogical and textural characteristics of the studied rocks indicate that copper and vanadium minerals in the Araba Formation are related to supergene processes and telodiagenesis after oxidation of sulfides and dissolution of feldspar grains and carbonate cement in the clastic rocks most probably during the Upper Devonian-Lower Carboniferous Hercynian event. In the Um Bogma Formation, copper mineralization is a supergene alteration of hydrothermal Fe-Mn minerals and associated primary Cu-Zn sulfides. Hydrothermal fluids likely mobilized several metals, i.e., Fe, Mn, and Cu, within dissolved and karstified carbonates in the Um Bogma Formation.

Green synthesis, crystal structure, linear and nonlinear optical investigation of MgO1-xMnOx nanocomposite via Z-scan technique

There is a wide range of refractory and electrical applications where magnesia is firmly established. In the current manuscript, the effect of MnO doping on linear and nonlinear optical traits of MgO was investigated. (MgO)1-x(MnO)x(x = 0,0.05,0.1) nanocomposites were synthesized via a green method using Starch powder. The XRD results showed that all the materials have a cubic structure with a lattice parameter of about 4.21 Å. The crystallite size decrease from 20.9 Å to 18.6 Å, as MnO content varied from 0 to 0.10. In addition, scanning electron microscopy showed a spherical morphology of (MgO)1-x(MnO)x, that increasing MnO component causes agglomaration. Increasing amount of × causes to decrease band gap of samples in which the Eg values for x = 0.00,0.05,and 0.10 were obtained 5.1,3.8,and 3.7 eV, respectively. The nonlinear optical properties of (MgO)1-x(MnO)x were evaluated using the Z-scan technique with a laser beam. Both nonlinear refractive index (10−8cm2/W) and nonlinear absorption (10−4cm/W) showed positive values, suggesting self-defocusing and saturable absorption. By increasing MnO component in (MgO)1-x(MnO)x nanocomposite, the nonlinear responses increase. According to interesting optical nonlinearity results of (MgO)1-x(MnO)x nanocomposites, it is a promising candidate for photonic and optical devises.

Effect of MnO content on the crystallization, physicochemical and dielectric properties of mica glass-ceramics

This paper has concentrated on the effect of partial substitution of MnO for MgO on the crystallization, physicochemical and dielectric properties of mica glass-ceramics. The results showed that MnO acted as a network modifier to diminish the network integrity. Fluorphlogopite (KMg3(Si3AlO10) F2) phase, as the dominant crystal phase, suggested that Mn2+ ions did not participate in forming the mica phase. The crystallinity achieved the maximum (67.96%) at a MnO doping of 4 mol%. From SEM images, the conclusion that appropriate MnO doping could promote the formation of nuclei and refine the grains can be obtained. When the doping of MnO was 4 mol%, the Vickers hardness (4.59 GPa) of mica glass-ceramics was the lowest, while the bending strength (136.84 MPa) and chemical stability reached the best. The dielectric constant was about 7–8 at 1 MHz, and the dielectric loss remained relatively low.

Chemical evolution of micas and Nb-Ta oxides from the Koktokay pegmatites, Altay, NW China: Insights into rare-metal mineralization and genetic relationships

This study focuses on the differences in the mineralization potentials and genetic relationships between representative rare-metal pegmatites and the muscovite granite in the Koktokay field in Altay, China, as well as the possible roles that magmatic and/or hydrothermal activities played in enriching the related rare metals. To this end, the major- and trace- element compositions of micas, the major- element compositions of Nb-Ta oxides, and the Li isotopic compositions of Li-rich muscovite, lepidolite, and spodumene were systematically analyzed. The major element compositions of the micas in the No. 1 and No. 2 pegmatites are quite similar. However, the MgO (0.89–2.18 wt%) and F (0.66–2.01 wt%) contents of the micas in the contact zone of the No.3 pegmatite are higher than those of the micas in the No. 1 and No. 2 pegmatites. In addition, the MnO (0.37–0.46 wt%) and MgO (0.39–0.59 wt%) contents of the micas in the muscovite granite are distinctly higher than those of the micas in the studied pegmatites. The trace-element compositions reveal that the primary micas from the small No. 1 and No. 2 pegmatites have significantly lower Li, Be, Ta, and Cs contents and a narrower range of fractionation relative to those in the large No. 3 pegmatite, indicating a significant difference in the rare-metal mineralization potentials of these pegmatites. Moreover, there is a large difference in the δ7Li values of the Li-rich minerals in the muscovite granites (−4.37–0.07‰), No. 3 (4.3–6.81‰) and No. 1 (7.44–14.65‰) pegmatites. These results support the hypothesis that the muscovite granite and pegmatite dikes may have formed independent of each other, and that their formations were a consequence of multi-stage magmatic activities. In addition, the Nb-Ta oxides in the outer zones are mainly columbite-(Mn). The large differences in the Nb/Ta ratios of the columbite-(Mn) (1.83–14.91) and primary micas (2.22–10.41) in the outer zones could be the result of silicate-silicate melt immiscibility. Furthermore, the low Nb/Ta ratios (commonly < 5) of the bright overgrowths of the columbite-(Mn) may have crystallized directly from a hydrous alkali-halogen-rich melt rather than from a hydrothermal fluid. The distinctly higher Ta (39–167 ppm), Cs (275–579 ppm), and B (213–245 ppm) contents; considerable Li contents (400–554 ppm), and lower Nb/Ta ratios (0.5–3.2) of the hydrothermal micas suggest that hydrothermal processes played an important role in the additional enrichment of the related rare metals (e.g., Ta, Cs, Li, and B).

Photocatalytic degradation of methyl orange in the presence of transition metals (Mn, Ni, Co) modified TiO2 coatings formed by plasma electrolytic oxidation

The effect of selected transition metals (Mn, Ni, Co) modified TiO2 coatings formed by plasma electrolytic oxidation of titanium on their surface morphology, phase and chemical composition, optical absorption, and photocatalytic degradation of methyl orange (MO) was investigated. Coatings were formed in an alkaline electrolyte with varying concentrations of MnO, NiO, or Co3O4 powders. The morphology, thickness and phase structure of all formed coatings are nearly identical and independent of the content of transition metal ions embedded in TiO2. The X-ray diffraction and X-ray photoelectron spectroscopy results indicated that anatase TiO2 coatings were loaded with MnO, NiO, or Co3O4 from electrolytes. When up to 2.0 g/L of MnO, NiO, or Co3O4 is added to the electrolyte, the photocatalytic activity (PA) of the forming coatings is higher than for pure TiO2. The coatings formed in electrolyte with the addition of 0.75 g/L MnO, 1.5 g/L NiO, or 2.0 g/L Co3O4 had the highest PA. Increased PA is associated with a decrease in photogenerated electron/hole recombination rate, according to UV–Vis diffuse reflectance spectroscopy and photoluminescence measurements.

Petrology and biotite geochemistry of Mengku granitoids in the Changning-Menglian suture zone, southwest China: Insights into magma evolution and Sn mineralization

The Changning-Menglian suture zone (CMSZ) is one of the major Sn metallogenic zones related to Triassic granitoids. However, the genetic relationship between magmatic petrogenesis and metallogeny is not well-constrained. Highly evolved granitoids are an important type of granitic rocks, given their close relationship with Sn mineralization. Here we provide monazite U-Pb data and comprehensive major-trace element (including halogen) data for biotites from the Mengku granitoids, to constrain their magma evolution and link to regional Sn metallogeny. Our U-Pb dating on monazite from the highly evolved granitoids yielded weighted mean age of 223.6 ± 1.4 Ma (n = 20, MSWD = 1.3). The new geochronologic results, coupled with recently reported ages from the Lincang batholith, suggest that most of the Lincang granitoids formed within a relatively consistent period at ca. 230–215 Ma. Geochemically, these Triassic granitoids can be divided into three groups. Group 1 granitoids display low Al2O3, P2O5, FeOT + MgO, Eu, Sr and Zr contents with high differentiation index (DI = 88–94) and A/CNK (1.07–1.17), consistent with the features of highly evolved granites. In contrast, Group 2 monzogranites and Group 3 dioritic enclaves have higher TiO2, P2O5, FeOT + MgO, Eu, Sr and Zr contents, comparable to I-type granites. All magmatic biotite grains are Mg-rich in composition (XMg = 0.44–0.60). A positive correlation between F and MnO contents in biotites from Mengku granitoids indicate that more evolved Group 1 magmas underwent fractional crystallization. The most evolved magmas (Group 1) have relatively low log(fH2O/fHF) values (4.34–5.05) and high log(fHF/fHCl) values (4.85–5.39), suggesting lower Cl contents and higher F contents than other magmas. Oxygen fugacities (logfO2) calculated from biotite equilibria for the Mengku granitoids are –22.2 to −17.7, straddling on the NNO and QFM buffers. Low log(fO2) values and positive correlation between Sn and log(fHF/fHCl) suggest that relatively reduced condition, highly evolved and F-rich granitic magmas are conducive to Sn mineralization in the CMSZ.

New Insights into Coloration Mechanism in Violet-Red Pyrope-Almandine

The most common type of garnet is pyrope-almandine, whose color varies from red to violet. In this study, 36 faceted gem-quality samples are used for electron microprobe, infrared spectrum, and UV-Visible spectrum test to find the coloration mechanism and spectroscopic characters in red-violet pyrope-almandine. The gradually increasing content of Mg2+ at the X position in the lattice is connected to the variation in the infrared spectrum. The wavenumber increases with the decrease of cationic radius, which makes the distance between C and D bands further. The color mechanism is mainly affected by Fe2+, and Mn2+. We discuss the change in colors with the assumption of a certain MnO content. When it is above or below the standard of 1 wt%, the absorption intensity of the UV-Visible spectrum is completely different in the purple zone, which determines the color to be red or violet. Therefore, the effect of Mn2+ and Fe2+ should be combined instead of being considered respectively. The results show that the MnO content can be quickly inferred by the light purple/fancy purple color. To avoid harming the value, this new insight makes it possible to quickly classify the gem quality in mining as well as in the market.

Structural, Optical, Magnetic and Photon Attenuation of Novel Potassium Lead Borate Glasses Doped with MnO

Potassium lead borate glasses doped with MnO (40B2O3 + 40PbO + (20-x)K2O + xMnO: x = 0–5 mol%) have been prepared via standard melting quenching process. The impact of MnO on the structure, optical, magnetic and gamma-ray protection properties of pottisium lead borate glasses have been examined. The density was increased from 4.83to 5.23 g/cm3 as MnO content increased while the molar volume of prepared glass sample was decreased from 28.112 to 25.755 cm3/mol. The obtained direct optical gap (Eg) values were 2.84, 2.59, 2.41, 2.19, 1.95, and 1.84 eV for the Mn-x (x = 0, 1, 2, 3, 4, and 5) glass samples, respectively. Fourier-transform infrared spectroscopy (FTIR) spectra demonstrated that as the MnO concentration increases in the glass network the intensity and width of the IR bands were increased. The magnetic measurement revealed that the magnetic saturation (Ms) was decreased while the magnetic coercivity (Hc) was increased with increasing MnO substitution ratio. The linear attenuation coefficient of the $${\mu }_{Mn-glass}$$ follows the order: µMn-0 < µMn-1 < µMn-2 < µMn-3 < µMn-4 < µMn-5. Half value layer (HVL) rises as µ decreases and vice versa. The range of the HVL is 0.002–3.378, 0.002–3.334, 0.002–3.291, 0.002–3.248, 0.002–3.176, and 0.002–3.106 cm for Mn-x (x = 0, 1, 2, 3, 4, and5). The trend of effective atomic number (Zeff) variation is related to that of both linear and mass attenuation coefficients (µ and µm). The produced Mn-glasses can be employed in a variety of optical, magnetic and radiation protective applications.

Exotic glass types and the intensity of recycling in the northwest Quarter of Gerasa (Jerash, Jordan)

Major and trace elements are presented for 149 glass fragments ranging in date from the Roman to Early Islamic periods (1st – mid-8th centuries CE), excavated during the Danish-German Jerash Northwest Quarter Project's fieldwork between 2011 and 2016. The results confirm a clear dominance of Levantine glass types, but also reveal 12 glasses of Egyptian and Mesopotamian compositions recovered from two houses destroyed by the major earthquake which hit parts of the Levant in January 749 CE. These closed and undisturbed contexts from the final phase of occupation reveal the presence of relatively more pristine Levantine as well as imported material that is less visible in earlier contexts in the Gerasa assemblage, where the recycling indexes are high and chemical signatures of any exotic glass were largely lost due to remelting and their dilution by the overwhelming quantities of glass produced in the Levantine region. This emphasizes that imported glass may frequently be underestimated or even invisible in glass compositional studies, depending on the archaeological context sampled and the approach taken to artifact quantification.Levantine glass was attributed to Roman, Late Roman (Jalame) and Byzantine/Early Islamic (Apollonia) productions based primarily on MnO, Al2O3 and Na2O concentrations, which offered an advantage over previous approaches. While colorants in weakly colored glass indicate recycled material, their concentrations are sensitive to context, with higher concentrations in the early periods when the use of intentionally colored glass was more frequent. We have therefore developed the concept of the intensity of recycling, which was estimated using components modified during prolonged melting, such as K2O, P2O5 and Cl. A pronounced enrichment in CaO, also dependent upon the intensity of recycling, may affect the assignment to compositional groups and should be taken into consideration in future. Recycling in Gerasa appears to have been more intensive than was the case for cities closer to the primary production centers on the Mediterranean coast, consistent with the view that the dependency on recycling increases further away from the source of the primary material. In contrast, the cities in the coastal plain could readily exploit the marine transportation network, which appears to have played a major role in the distribution of raw glass. (361 words).