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Tourmaline is a widespread borosilicate mineral that is well known for its variable chemistry. Although a major amount of octahedral Al in tourmaline is commonplace, the occurrence of significant amounts of tetrahedral Al is relatively rare. This paper focuses on tourmaline from the collection of the A.E. Fersman Mineralogical Museum (Russia) originated from Italy with up to 25% of Si replaced by Al at the tetrahedral site. The tourmaline is characterized by optical and scanning electron microscopy, Raman spectroscopy, infrared spectroscopy, Mössbauer spectroscopy, energy-dispersive and wavelength-dispersive X-ray analysis, laser ablation inductively coupled plasma optical emission spectrometry and single-crystal X-ray diffraction. The studied tourmaline occurs as transparent dark blue crystals (with equant external morphology) up to 3 mm in size and forms veinlets cutting a (Mg,Al)-rich metamorphosed mafic-ultramafic rock (Mg >> Fe) composed of spinel, pargasite, clinochlore, phlogopite, and hydroxylapatite. The studied tourmaline meets the criteria defining magnesio-lucchesiite and can be compositionally formed via Tschermak-like ([6]Me2+ + [4]Si4+ ↔ [6]Al3+ + [4]Al3+, where [6]Me2+ = Mg,Fe) or plagioclase-like ([9]Ca2+ + [4]Al3+ ↔ [9]Na+ + [4]Si4+) substitutions. Zones with a relatively high Si content (Si-rich) have pronounced indications of dissolution, while silicon-depleted zones (Si-poor) overgrow Si-rich zones, eventually creating a visible replacement zone of the crystal. We suggest that Si-poor tourmaline results from the Si-rich tourmaline losing Si during a metasomatic process. The resulting empirical crystal-chemical formula for the Si-poor zone is: X     C a   0.95     N a   0.03     ◻ 0.02         Σ 1.00     Y     M g   1.08     A l   0.98     F e   0.50   2 +     F e   0.43   3 +         Σ 3.00     Z     A l   5.91     F e   0.09   3 +         Σ 6.00     T     S i   4.57     A l   1.43         Σ 6.00     O   18           (BO3)3V(OH)3W[O0.95(OH)0.05]Σ1.00 [a = 15.9811(2), c = 7.12520(10) Å, R1 = 1.7%] and for the Si-rich zone is: X     C a   0.89     N a   0.11         Σ 1.00     Y     M g   1.55     A l   0.80     F e   0.34   2 +     F e   0.31   3 +         Σ 3.00     Z     A l   5.51     M g   0.44     F e   0.05   3 +         Σ 6.00     T     S i   5.35     A l   0.65         Σ 6.00     O   18           (BO3)3V(OH)3W[O0.93(OH)0.07]Σ1.00 [a = 15.9621(3), c = 7.14110(10) Å, R1 = 1.7%]. According to pressure-temperature (P-T) calculations of mineral assemblage stability and comparable data on synthetic [4]Al-rich tourmalines, the studied tourmaline was formed at 600–750 °C and 0.10–0.20 GPa. The formation of tetrahedral Al-rich tourmalines requires several unusual factors: (1) desilication of primary rocks and (2) high temperatures and relatively low pressures. [ABSTRACT FROM AUTHOR]

Struvite (MgNH4PO4·6H2O) is a mineral first identified in 1845. It is being tested for several reasons: (1) it is a problem in liquid wastewater treatment plants; (2) on the other hand, it is recovered from these wastewaters for its phosphorus, magnesium and nitrogen; (3) is the main component of microbial-induced urinary stones. We have recently shown that struvite is ferroelectric and piezoelectric. In this paper, we present the first experimental evidence of the pyroelectric nature of struvite. Using a single-diffusion gel growth technique, we grew struvite crystals as flat, parallel plates. We performed measurements of pyroelectric currents on struvite of this shape, using it as a dielectric of a plate capacitor. The occurrence of pyroelectric effects in struvite was investigated by measuring depolarization currents as a function of temperature. This technique allows the disclosure of ferroelectric/pyroelectric transitions as well as the reconstruction of the ferroelectric loop. We found that the value of the pyroelectric coefficient p attains a maximum of 22 × 10−6 C m−2 K−1 slightly below room temperature, going down to p ≅ 10 × 10−6 C m−2 K−1 at room temperature. This value is comparable to values for other minerals. For example, the pyroelectric polarization coefficient of tourmaline, the mineral for which the pyroelectric effect was first discovered, is 4 × 10−6 C m−2 K−1. This value is 2.5 times lower than that measured for struvite, illustrating struvite's fairly strong pyroelectricity. [ABSTRACT FROM AUTHOR]

The controllable electrical and optical properties of two-dimensional tungsten disulfide (WS2) attracted much attention in photocatalysis, but commercial development has been severely restricted by their restacking properties. Surfactant-assisted synthesis techniques can be considered as an effective option to break this bottleneck. In this work, the effect of surfactants including sodium dodecylbenzene sulfonate (SDBS), hexadecyltrimethylammonium bromide (CTAB), and polyvinylpyrrolidone (PVP) on the microstructure of WS2/tourmaline composites prepared by coupled hydrothermal and calcination methods was explored. The WS2 nanosheets were uniformly deposited on the tourmaline surface with the assistance of 1.0 mmol/L SDBS. Meanwhile, WS2/Tour-SDBS exhibited the highest rhodamine B (RhB) degradation activity, which was 1.8 and 2.3 times higher than that of photocatalysts prepared with CTAB and PVP under the same conditions, respectively. This study provides a new tactic for the fabrication of high-performance WS2-based composites. [ABSTRACT FROM AUTHOR]

Serpentinite dehydration in subduction zones plays a pivotal role in geochemical cycling on Earth. A number of geochemical studies on arc magmas have elucidated the contributions of serpentinite-derived fluids to mantle sources. However, due to complex geological overprints during subduction zone processes, discerning serpentinite signatures in exposed metamorphic rocks within fossil subduction zones remains challenging. In this study we address these difficulties through in-situ investigations of tourmaline, the geochemistry of which reflects the host environment as well as potential fluid-induced processes. The presence of zonations in tourmaline makes it an excellent recorder of consecutive geological events. Integrated major and trace elements along with in-situ boron isotopes of tourmaline from the high-pressure Sopron area (Hungary) in the Eastern Alps were used to unravel fluid action sourced from serpentinite. Despite the presence of color zoning, tourmaline in the orthogneiss (Tur-G) has low X Mg [Mg/(Mg + Fe)] of ca. 0.3–0.6 and δ11B values of around −11 ‰, along with variable trace element compositions. Petrological observations and geochemical analyses suggest that the inner domains of Tur-G are of igneous origin, while the outer rims are likely affected by subsequent metamorphic events. Tourmaline in metasomatized kyanite-quartzite (Tur-K) veins exhibits distinct geochemical zoning, and preserves metamorphic cores and fluid-induced rims. The inner domains of Tur-K display low X Mg (<0.6), relatively high trace element concentrations and δ11B values of less than −10 ‰, whereas the overgrowths exhibit extremely high X Mg values (>0.99), low trace element concentrations and high δ11B values reaching up to +21 ‰, clearly indicating the incorporation of serpentinite-derived Mg-11B-rich fluids. Through comparison with other metamorphic and metasomatic tourmalines in (ultra)high-pressure rocks globally, we establish that tourmaline with high X Mg > 0.85 and δ11B values >0 ‰ may serve as an effective proxy for detecting serpentinite-derived fluids in subduction zones. [ABSTRACT FROM AUTHOR]

This study, conducted a spectroscopic analysis of 10 gem-quality blue tourmaline samples from Minas Gerais, Brazil, focused on detailed variations in their infrared, Raman, and UV-VIS spectra. Conventional gemological tests, electron-probe microanalysis, infrared spectroscopy (mid- and near-infrared), Raman spectroscopy, and UV-visible spectroscopy were used to systematically analyze the chemical composition and spectral characteristics of the samples. The infrared spectra revealed vibrations of [YO6], [TO4], [BO3], [OH], and H2O groups, indicating different bonding profiles, with the [OH] vibrational frequency showing a direct correlation with FeO and MnO content. The Raman spectra primarily reflected the stretching vibrations of metal–oxygen bonds and hydroxyl groups, indicating the complexity of the local environment in the crystal structure. The UV-VIS spectra showed that the broad absorption band around 725 nm was due to intermetallic charge transfer between Fe2+ and Fe3+. This work provides new insights into the local bonding environment within the crystal structure by providing precise spectral data of natural blue tourmaline, and a more accurate classification and evaluation of blue tourmaline through fine spectral change characteristics related to crystal chemistry has important implications for both academic research and the gemstone industry. [ABSTRACT FROM AUTHOR]

In view of the flue gas characteristics of cement kilns in China, the development of low-temperature denitrification catalysts with excellent anti-poisoning performance has important theoretical and practical significance. In this work, a series of MnCeOx@TiO2 and tourmaline-containing MnCeOx@TiO2-T catalysts was prepared using a chemical pre-deposition method. It was found that the MnCeOx@TiO2-T2 catalyst (containing 2% tourmaline) exhibited the best low-temperature NH3-selective catalytic reduction (NH3-SCR) performance, yielding 100% NOx conversion at 110 °C and above. When 100–300 ppm SO2 and 10 vol.% H2O were introduced to the reaction, the NOx conversion of the MnCeOx@TiO2-T2 catalyst was still higher than 90% at 170 °C, indicating good anti-poisoning performance. The addition of appropriate amounts of tourmaline can not only preferably expose the active {001} facets of TiO2 but also introduce the acidic SiO2 and Al2O3 components and increase the content of Mn4+ and Oα on the surface of the catalyst, all of which contribute to the enhancement of reaction activity of NH3-SCR and anti-poisoning performance. However, excess amounts of tourmaline led to the formation of dense surface of catalysts that suppressed the exposure of catalytic active sites, giving rise to the decrease in catalytic activity and anti-poisoning capability. Through an in situ DRIFTS study, it was found that the addition of appropriate amounts of tourmaline increased the number of Brønsted acid sites on the catalyst surface, which suppressed the adsorption of SO2 and thus inhibited the deposition of NH4HSO4 and (NH4)2HSO4 on the surface of the catalyst, thereby improving the NH3-SCR performance and anti-poisoning ability of the catalyst. [ABSTRACT FROM AUTHOR]

Understanding processes that occur during pegmatite crystallization are important for understanding magma evolution and enrichment processes of e.g. strategic and rare metals in pegmatites. Several processes are involved in the formation of pegmatites, and among these the timing of fluid saturation and exsolution is a critical area of investigation. The primary question focuses on if the timing of these processes influences pegmatite crystallization and the concentration of elements. The understanding of the relationship between fluid dynamics and mineralization is essential to develop comprehensive models of pegmatite formation. The unidirectional tourmaline prisms and quartz-tourmaline intergrowths (QTIs), composed of a central tourmaline surrounded by skeletal tourmaline intergrown with quartz are anisotropic textures, linked to disequilibrium crystallization at high degrees of undercooling. This study aims to trace fluid saturation and evolution in the outer zones of internally zoned pegmatites and to provide more accurate temperature constraints for their crystallization, using the Emmons pegmatite (Maine, USA) as a case study. The methodology comprises detailed inclusion petrography, microthermometric analyses, Raman spectroscopy, and LA-ICP-MS analyses. The results indicate that localized fluid saturation occurs early during the magmatic stage of pegmatite crystallization. At this point, the crystallizing mineral assemblages are composed of feldspar, muscovite, quartz, tourmaline, and minor garnet. The exsolved fluid is similar throughout the host tourmalines and is characterized by an H 2 O-NaCl-CO 2 -(N 2 -CH 4) composition. Temperatures, which are obtained from primary fluid inclusion isochores vary between 315 °C and 440 °C and confirm that the pegmatite crystallized at undercooled conditions. A decrease in temperature occurs on a centimeter scale between the central tourmaline and the skeletal tourmaline of the QTIs, which could be caused by a nucleation delay within individual boundary layers that are formed around the central tourmaline of the QTI. The higher concentration of water and other incompatible components, including fluxes, in the boundary layer led to fluid exsolution localized at the crystal-melt interface. The increased concentration of fluxes causes a nucleation delay, increasing the degree of undercooling and consequently leading to the skeletal morphologies seen in the QTIs. Furthermore, studied melt inclusions indicate that a compositionally modified melt was present during tourmaline crystallization, confirming the existence of a boundary layer at centimeter to decimeter scale. [ABSTRACT FROM AUTHOR]

Selected crystals of natural K-bearing tourmalines, extracted from a quartzofeldspathic rock from the Kumdy-Kol microdiamond deposit (an ultrahigh-pressure region of Kokchetav Massif, northern Kazakhstan), were characterized using a scanning electron microscope, an electron microprobe and single-crystal X-ray diffraction to investigate the impact of K uptake on the tourmaline structure. All the studied crystals belong to the maruyamaite–oxy-dravite/dravite compositional field, with K contents ranging from 0.03 to 0.47 apfu (atoms per formula unit), and contain a minor fluor-uvite component that increases towards oxy-dravite and dravite. The compositional variability of our samples can be expressed as a sequence of substitutions ranging from maruyamaite to oxy-dravite, dravite and fluor-uvite (or vice versa). Specifically, the substitutions that lead from maruyamaite to oxy-dravite to dravite are (1) X K + Al TOT + O1 O ↔ X Na + Mg TOT + O1 O and (2) X Na + Mg TOT + O1 O ↔ X Na + Mg TOT + O1 OH, respectively. Conversely, the substitutions that lead from oxy-dravite to dravite to fluor-uvite are (1) X Na + Mg TOT + O1 O ↔ X Na + Mg TOT + O1 OH and (2) X Na + Mg TOT + O1 OH ↔ X Ca + Mg TOT + O1 F, respectively. By analysing the difference between the bond valence sum and mean formal charge at the X site, we show that an increase in the K content (K > 0.21 apfu) results in the compression of X –O bonds (overbonded cation). Conversely, lower K contents lead to the stretching of the bonds (underbonded cation). Compared to the K-dominant analogues with Z FeO 6 povondraite-type framework, K-bearing tourmalines with a smaller Z AlO 6 framework such as maruyamaite should only be stable at higher-pressure conditions, as pressure is necessary to squeeze the relatively large K cation into the tighter X cavity. In both cases, the essential condition for the formation of K-dominant tourmalines is the extremely high K activity in the crystallization fluid. The K-tourmaline from the Kokchetav Massif may have crystallized under high-pressure (HP) conditions, with an upper limit between 3.5–7 GPa, during retrograde metamorphism following the ultrahigh-pressure (UHP) metamorphic peak. [ABSTRACT FROM AUTHOR]

This is an article in the field of mineral materials. The tourmaline powder was modified with silane coupling agent KH-171, and the process conditions were optimized with the parameters of contact angle and turbidity of the modified product in liquid paraffin. The test results showed that the contact angle of the resulting modified tourmaline reached 133 ℃ when reacted at 60 ℃ for 2 h at a system pH value of 9, a dosage of modifier KH-171 of 2 mL, and an alcohol-to-water ratio of 1∶5, showing excellent hydrophobic properties. The modified tourmaline was characterized by IR, SEM and XRD. The results showed that the organic functional groups with carbon-carbon double bonds were successfully connected to the surface of tourmaline without changing the original crystal structure, but the agglomeration of tourmaline reduced effectively and showed better dispersion performance.

Controlling blood loss is crucial for saving lives during trauma. Based on the current application of solid waste in hemostatic materials, this study reports the synthesis of a hydroxyapatite/tourmaline composite material (referred to as ST) and a hemostatic sponge (referred to as STS). These materials were synthesized through hydrothermal processes and lyophilization techniques using seashells, tourmaline, and chitosan as precursors. The phase analysis and microstructure characterization were performed using XRD, SEM, TEM, and HRTEM. Owing to the spontaneous polarization of tourmaline attracting free ions in the system, the shells were deposited on the surface of tourmaline particles in the form of hydroxyapatite (HA) through dissolution and recrystallization during the hydrothermal process. HA can release free Ca2+, an important component in the coagulation system, while tourmaline can enhance cell metabolism by reducing water molecular clusters, thereby altering the permeability of cell membranes. ST particles were incorporated into the chitosan sponge matrix to prevent particle shedding. Through orthogonal design experiments on the preparation process of ST, the optimal preparation conditions were determined as follows: a hydrothermal temperature of 180 °C, a hydrothermal time of 12 h, a pH value of 8, and a shell-to-tourmaline ratio of 8 : 1. The composite materials were evaluated for their adsorption capacity, clotting time, hemolysis rate, antibacterial rate, and cytotoxicity. The results demonstrated a higher liquid adsorption rate, significantly reduced clotting time, a hemolysis rate of <5.0%, an antibacterial capacity of 88.5%, and lower cytotoxicity. These findings suggest that STS has the potential to be a safe, effective, and cost-efficient hemostatic agent. [ABSTRACT FROM AUTHOR]

The article provides generalized data on the geological structure, the results of laboratory analyzes of the heavy fraction of the main placer-forming minerals of the Vovchansk zircon-rutile-ilmenite deposit, which was being developed by Demurinsky Mining and Processing Plant LLC in 2002. The geological structure of the Vovchansk deposit includes a complex of Precambrian rocks of the crystalline basement, the Paleozoic-Cenozoic weathered crust, the Paleozoic-Cenozoic sediments, and Quaternary deposits. The industrial concentration of heavy minerals is confined to the middle and upper parts of the Middle Sarmatian subsuite of the Neogene, composed of fine-grained, essentially quartz sands, with a total thickness of 0.4 to 63 m. The content of heavy minerals in the ore-bearing horizon of the deposit ranges from 93.8 to 485 kg/m³ (ilmenite from 37.6 to 242.6 kg/m³, rutile from 15.9 to 64.6 kg/m³, zircon from 2.9 to 9.4 kg/m³, sillimanite and disthene from 20.4 to 117.5 kg/m³). The content of major and minor elements-impurities in individual minerals of the ore-bearing horizon (178 grains) was determined: ilmenite (18 samples), rutile (40 samples), zircon (35 samples), sillimanite (30 samples), staurolite (25 samples), tourmaline (12 samples), ganite (8 samples), monazite (10 samples). The conducted research clarified the typomorphic features of minerals from the sands of the Vovchansk deposit, established their absolute age and probable original sources. [ABSTRACT FROM AUTHOR]

Source‐to‐sink systems respond to and therefore potentially record topographic and tectonic changes. North of the Tian Shan Belt, the Sikeshu subbasin of the SW Junggar Basin transitioned from active extension in the Triassic to post‐extensional subsidence in the Jurassic‐Cretaceous. Sediment in the Sikeshu subbasin has been shown to be derived from the Tianshan. However, the details of the source‐to‐sink system remain unclear and discrepancies exist between proxy records. The heavy minerals in the Middle Triassic in the Sikeshu subbasin are dominated by garnets. To investigate the garnet sources and decipher the Mesozoic source‐to‐sink evolution, we conducted petrological and sedimentary analysis and detrital garnet and tourmaline geochemistry. We found that the geochemistry of garnets in the Middle Triassic sandstone is most consistent with that of the skarns in the Yili Block (YB) in Tianshan, while the geochemistry of 55%–84% of garnets in other Mesozoic sandstones is consistent with that of garnets in amphibolites in the YB. The geochemistry of the tourmalines since the Upper Triassic is consistent with that of the meta‐sedimentary rocks in the YB and Central Tianshan Block. The dominance of garnets sourced from skarns in the Middle Triassic probably indicates a near‐source point provenance and the broader range of garnet compositions from the Upper Triassic–Lower Cretaceous suggests multiple sources. We infer that the point source changed to multiple sources, which is consistent with the zircon spectra changing from unimodal to multimodal. This change reflects the expansion of the drainage that accompanies a change from active rifting to a post‐rift stage. Key Points: Provenance changed from a point source from skarns during the syn‐rift stage to multiple sources during the post‐rift stageHigher relief in the Tianshan in the Triassic was reduced during the Jurassic‐CretaceousSediment recycling took place in the Early Cretaceous [ABSTRACT FROM AUTHOR]

• Construct a superactive, friendly and cost-effective catalyst from natural tourmaline. • Catalyst is superior to P25 in activating PMS and degrading antibiotic in real waters. • It can degrade tetracycline in a wide concentration range. • Above 98.7% of tetracycline was degraded in seawater within 5 min. • The catalytic reaction mechanism was explored and proposed. • The eco-friendly catalyst can be recycled and reused for multiple cycles. Reasonably designing highly active, environmentally friendly, and cost-effective catalysts for efficient elimination of pollutants from water is desirable but challenging. Herein, an efficient heterogeneous photo-Fenton catalyst tourmaline (TM)/tungsten oxide (WO 3-x) (named TW10) containing tungsten/boron/iron (W/B/Fe) synergistic active centers and 90% of cheap natural tourmaline (TM) mineral rich in Fe and B elements. The TW10 catalyst can quickly activate peroxymonosulfate (PMS) to generate massive active free radicals, which may induce the rapid and efficient degradation of tetracycline (TC). The TW10/PMS/Visible light system can effectively degrade up to 98.7% of tetracycline (TC) in actual waters (i.e. seawater, Yellow River, and Yangtze River water), and the catalytic degradation rates reach 1.65, 5.569, and 2.38 times higher than those of TM, WO 3-x , and commercial P25 (Degussa, Germany), respectively. In addition, the catalyst can be recycled and reused multiple times. Electron spin resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS), and liquid chromatograph-mass spectrometer (LC-MS) analyses confirm that the synergistic catalytic effect of W/B/Fe sites on the TW10 catalyst accelerates the electron transfer between Fe(II) and Fe(III), as well as between W(V) and W(VI), and thus promotes the rapid degradation of TC. The catalytic reaction mechanism and degradation pathway of TC were explored. This work provides a feasible route for the design and development of new eco-friendly and efficient catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Tourmaline, a boron-bearing mineral, has been extensively applied as a geothermometer, provenance indicator, and fluid-composition recorder in geological studies. In this paper, the decomposition capability of an HF-HNO3–mannitol mixture for a tourmaline sample was investigated in detail for the first time, and a wet acid digestion method based on the boron–mannitol complex for accurate boron determination in tourmaline by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. With a digestion temperature of 140 °C, tourmaline samples of 25 mg (±0.5 mg) can be completely decomposed by a ternary mixture, which consisted of 0.6 mL of HF, 0.6 mL of HNO3, and 0.7 mL of 2% mannitol (wt.), via a continuous heating treatment of 36 h. Following gentle evaporation at 100 °C, the sample residues were re-dissolved using 2 mL of 40% HNO3 solution (wt.) and diluted to about 2.0 × 105-fold by a two-step method using 2% HNO3 solution (wt.). The boron contents in a batch of parallel tourmaline samples were then determined by ICP-MS, and results showed that the boron concentration levels were in a range of 3.20–3.44% with determination RSDs less than 4.0% (n = 5). It was found that the boron concentrations obtained at the mass of 10B were comparable with results from the measurements at the mass of 11B. This revealed that the usage of 2% mannitol with a quantity as high as 0.7 mL in this developed approach did not exhibit significant effect on the quantification accuracy of boron at the mass of 11B. It was also found that the processes including fluoride-forming prevention and fluoride decomposition deteriorated the boron-reserving efficiency of mannitol for tourmaline, causing the averaged boron contents to vary from 2.25% to 3.57% (n = 5). Furthermore, the stability of the boron–mannitol complex under 185 °C by applying the laboratory high pressure-closed digestion method was evaluated, which showed that there existed a 60.36% loss of boron compared to that under 140 °C by using this proposed approach. For this ternary mixture, the tourmaline decomposing efficiency was found to be weakened prominently using 100 °C as the digestion temperature, and tourmaline powders can be observed even after 72 h of continuous heating with B contents within 1.09–1.23% (n = 5). To assess the accuracy of this developed method, the boron recovery of anhydrous lithium tetraborate was studied. It was found that the boron recoveries were within 96.59–102.12% (RSD < 1%, n = 5), demonstrating the accuracy and reliability of this proposed method, which exhibits advantages of high B preserving efficiency, and giving concentration information of both B and trace elements simultaneously. By applying such a boron–mannitol complex-based wet acid digestion method, the chemical composition of boron and trace elements in three tourmaline samples from different pegmatites were quantified, which provided valuable information to distinguish regional deposits and the associated evolution stages. [ABSTRACT FROM AUTHOR]

In the SE Alps, two Cretaceous–Eocene flysch basins, Julian and Brkini, filled with turbidite sediments, are present. This study novelly reports heavy mineral assemblage counts and detrital tourmaline characterization for 11 samples. It is possible to define three different groups, characterized by the presence of (1) a clinopyroxene–epidote–low-ZTR (zircon+tourmaline+rutile; 5%) sample association, (2) a high-ZTR (>48%)–garnet–apatite association and (3) a low-ZTR (<40%)–Cr-spinel–garnet association. Detrital tourmalines from both the Julian and Brkini flysch basins are rather similar in composition, associated with metapelites and metapsammites coexisting or not coexisting with an Al-saturating phase, ferric-iron-rich quartz–tourmaline rocks and calc–silicate rocks; however, their number is drastically different. In fact, even if the percentage of heavy minerals is very low and similar in both basins (0.17–1.34% in weight), in the Julian basin, the number of tourmaline crystals is much lower than that in Brkini (1–14 vs. 30–100), suggesting an important change in the provenance area. Interestingly, the presence of a high amount of tourmaline derived from ferric-iron-rich quartz–tourmaline rocks and calc–silicate rocks makes these two basins different from all the Cretaceous flysch basins of Bosnia and the Northern Dinaric zone, where these supplies are missing or very limited. [ABSTRACT FROM AUTHOR]

Tourmaline is a valuable forensic mineral that contains a wide range of elemental components capable of reconstructing its geologic evolution. In this study, we developed detailed petrographic and geochemical research on tourmaline-bearing rocks and tourmalinites found surrounding the ca. 3.30 Ga rhyolite of the Gavião Block, northern São Francisco Craton. Two distinct types of mineral assemblages in the tourmaline-bearing rocks are recognized based on the presence of sulfides, oxide minerals, and carbonaceous matter. Along with these tourmaline-bearing rocks, tourmalinite samples are found. The mineral chemistry of tourmalines from the two types of tourmaline-bearing rocks reveals mainly schorl-dravite as tourmaline from a mineral assemblage containing quartz, tourmaline, pyrite, and hematite, and a diverse composition ranging from schorl-dravite, feruvite-uvite, and schorl-feruvite solid solutions for tourmalines present in the mineral assemblage that contains quartz, pyrite, and carbonaceous matter. The tourmaline composition is essentially foitite-schorl in tourmalinite samples. Most of the metasedimentary rocks studied have felsic and mafic source compositions. The interaction of hydrothermal fluid was crucial for the formation of sulfide and tourmaline minerals. However, distinct tourmaline origins are recognized in tourmaline-rich rocks, pointing out the relevance of sedimentary and metamorphic processes. [ABSTRACT FROM AUTHOR]

The geographic provenance of minerals provides key insights into a range of geologic problems, including the source of gem materials. The tourmaline supergroup is unparalleled in its ability to record and preserve extensive chemical signatures of its formational environment. To evaluate the likelihood that tourmalines of similar compositions from separate geographic localities could be differentiated, a multivariate statistical approach has been utilized on two complementary data sets. These chemical analytical data sets of copper-bearing "Paraíba" tourmaline include data sets acquired with Laser Induced Breakdown Spectroscopy (LIBS) and electron microprobe analysis (EMPA). Fifty-four samples of copper-bearing tourmalines from known source locations from Brazil (São José de Batalha of Paraíba state and the neighboring Rio Grande do Norte state), Mozambique, and Nigeria, were analyzed using LIBS with a subset of these samples analyzed by EMP. Data sets obtained by each method were evaluated with multivariate statistics (PCA, PLSR). Although the sample set is limited, sequential PLSR modeling of the spectra clearly distinguished the four localities with high success: >95% for LIBS and >87% for EMP. The statistical analyses of the two techniques, LIBS and EMP, suggest that each technique emphasizes different elements for discrimination when considered in the context of the available data. The elements Cu, Mn, Fe, Mg, Ti, Zn, K, H, Co, and V were significant in LIBS chemometric models. Statistically significant elements in EMP models were Mn, Cu, Al, Ca, K, and F. Each technique results in a robust determination for geographic provenance of tourmalines with comparable compositions. The significant distinguishing chemical elements reflect geochemical distinctions in each host environment that are imparted on the tourmaline. Multivariate statistics applied to LIBS and EMP data provide an effective tool for provenance discrimination of Paraíba tourmalines, distinguishing Brazilian-sourced samples from African-sourced materials. These data provide new methods for separating the geographic origin of minerals with very similar composition such as demonstrated here for copper-bearing tourmalines. [ABSTRACT FROM AUTHOR]

This is an article in the field of mineral processing engineering. Tourmaline has been widely used for its spontaneous polarity, pyroelectric effect, far-infrared radiation and negative-ion release effect. In order to increase its stability in water-based coatings and improve its performance in water-based coatings, in this work, the surface modification of tourmaline with carboxylated nanolocellulose (C-CNF) was studied and optimized. The test results show that the performance of modified tourmaline was optimal while the addition of C-CNF was 2 g, solid-to-liquid ratio 1:5, and reacted 2h at 50 ℃, its turbidity reached 1361 ntu, contact angle to 53o. It was found that C-CNF was successfully grafted to the tourmaline surface by means of characterization of the modified tourmaline, and the dispersion of the modified tourmaline in the aqueous medium was better improved.

In recent decades, groundwater pollution has emerged as a pressing environmental concern, with particular attention directed towards the prevalence of Methyl Tert-Butyl Ether (MTBE), a hydrocarbon compound originating from leaks in underground storage tanks and the widespread use of MTBE-infused gasoline. This study evaluates the efficacy of the permeable reactive barrier (PRB) method employing four novel adsorbents - Aerogel, Sillimanite, Andalusite, and Tourmaline - for MTBE removal from groundwater. A series of batch and column experiments were conducted to investigate the adsorption capabilities of these materials. Batch experiments revealed promising adsorption capacities of 6.25, 5.8, 4.9, and 5.1 mgMTBE/gadsorbent for aerogel, sillimanite, andalusite, and tourmaline, respectively, reaching equilibrium within 120, 240, 240, and 240 minutes, respectively. Subsequently, column studies were undertaken to analyze MTBE removal using a laboratory-scale pilot. Maximum adsorption capacities of 13.4, 4.2, 2.24, and 3.72 mgMTBE/gadsorbent were observed for aerogel, sillimanite, andalusite, and tourmaline, respectively, with corresponding bed lives of 160, 290, 107, and 224 minutes. These findings underscore the potential of the PRB method utilizing innovative adsorbents for effective MTBE remediation in groundwater systems, offering environmentally-friendly solutions and paving the way for sustainable water management practices.

Using zinc oxide (ZnO), tourmaline (TM), and polyethylene terephthalate (PET) as main raw materials, a novel ZnO/TM/PET negative ion functional fiber was created. The rheological properties of a ZnO/TM/PET masterbatch were investigated; the morphology, XRD, and FT-IR of the fibers were observed; and the mechanical properties, thermal properties, and negative ion release properties of the new fiber were tested. The results showed that the average particle size of the ZnO/TM composite is nearly 365 nm, with an increase in negative ion emission efficiency by nearly 50% compared to the original TM. The apparent viscosity of fiber masterbatch decreases with the increase in the addition of the ZnO/TM composite, and the rheological properties of the PET fiber masterbatch are not significantly effected, still showing shear thinning characteristics when the amount of addition reaches 10%. The ZnO/TM composite disperses well in the interior and surface of the ZnO/TM/PET fiber matrix. The prepared ZnO/TM/PET fiber has excellent properties, such as fineness of 1.54 dtex, glass transition temperature of 122.4 °C, fracture strength of 3.31 cN/dtex, and negative ion release of 1640/cm3, which shows great industrialization potential. [ABSTRACT FROM AUTHOR]

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The anisotropic textures, including unidirectional solidification textures and graphic intergrowths, characteristic for pegmatites, are interpreted to result from disequilibrium crystallization at high degrees of undercooling. Experimental studies have revealed the existence of thin boundary layers surrounding the rapidly growing crystals. Here, tourmaline-bearing samples from the outer zones of the Emmons pegmatite (Maine, U.S.A.) are used to examine if a boundary layer can also occur in natural samples. Crystal morphology is linked with geochemistry to understand the evolution of pegmatite melts and to constrain disequilibrium conditions at large degrees of undercooling. Petrographic studies and semiquantitative micro-X-ray fluorescence element mapping were conducted to identify crystal morphology and zonation, complemented with electron microprobe analyses to determine major and minor element compositions and LA-ICP-MS analyses of selected trace elements. Three textural groups were identified: comb-like tourmaline, quartz-tourmaline intergrowths, and radiating tourmaline. The intergrowths are optically coherent and are split into three different morphologies: central, second tier, and skeletal tourmaline. Most tourmaline is schorl, but chemical variation occurs on three different scales: between textural groups, between different morphologies, and intracrystalline. The largest scale geochemical variation is caused by the progressive evolution of the melt as it crystallized from the borders inwards, while the intracrystalline variations are attributed to sector zoning. A model is suggested where the systematic variation of Mg, Mn, and Fe within individual intergrowths is proposed to be the result of crystallization from a boundary layer, rich in water and other fluxing elements (e.g., Li, P, B), formed around the rapidly growing central tourmaline. Here, we show the first examples of boundary layers in natural pegmatites. Furthermore, the results bring into question whether boundary layer tourmaline can be used as a bulk melt indicator in pegmatitic melts. [ABSTRACT FROM AUTHOR]

Late-Pan-African granitic pegmatites in Malawi host gem mineralization (tourmaline, beryl/aquamarine/heliodor). We use major and trace element chemistry of mica and tourmaline as proxies to describe the geochemical characteristics and to analyze the evolution of the pegmatite-forming melts. Trace element contents and ratios of pegmatitic micas and tourmalines show characteristic fractionation trends. Mica from highly fractionated pegmatite typically shows high Rb, Cs, Zn, Nb, Ta, F, and Li concentrations but low Ni, Co, V, Ti and Sc concentrations. In their less fractionated counterparts, these compositional patterns are largely reversed. Exceptions in these element patterns are related to the presence or absence of other phases that may fractionate specific elements more strongly than mica. Tourmaline shows similar fractionation trends in major and trace elements. The observed patterns indicate fractional crystallization as the dominant process of melt evolution. A near exponential decrease of alkali element ratios, such as K/Rb and K/Cs, and an increase in Rb, Cs and Li in white mica from the less to the more strongly differentiated zones suggest Rayleigh fractional crystallization. The modelling of these element ratios shows that in different pegmatite bodies the least differentiated zone formed at a fractionation coefficient of F = 0.35–0.5. Zones of intermediate fractionation show F = 0.85–0.9. Gem mineralization is associated with the most highly fractionated pegmatites or pegmatite zones (F = ~ 0.99). These highly fractionated pegmatites show strong enrichment of Li, Rb and Cs in mica and tourmaline forming from melts rich in incompatible elements. The crystallization of gem phases depended on this highly enriched environment. [ABSTRACT FROM AUTHOR]

Coal gasification technology is essential for realizing clean and efficient conversion of coal, as well as for reducing carbon emissions. However, coal gasification technology is accompanied by a large amount of coal gasification wastewater that is biodegradable. In this work, tourmaline was applied as a catalyst in electro-Fenton like process for treating coal gasification wastewater. The optimal applied parameters of coal gasification wastewater were investigated as follows: current density of 90 mA cm−2, tourmaline dosage of 8 g L−1, electrode gap of 1 cm, and temperature at 25 °C; the COD removal ratio reached 91.24% after 240-min treatment. In addition, the current density and tourmaline dosage were further optimized by response surface method. The result was about current density with 82.4 mA cm−2 and catalyst with 7.57 g L−1; the predicted COD removal efficiency was 86.91%. Under the optimal parameters the actual COD removal efficiency was 88.25% a little high than the predicted value. To explore the reusability of tourmaline as Fenton reaction catalyst, five cycles of experiments were carried out. The result demonstrated that tourmaline could be used as catalyst for treating coal gasification wastewater by electro-Fenton like process. [ABSTRACT FROM AUTHOR]

Piezoelectric materials can convert mechanical energy into electrical energy, and further piezocatalysis can be designed based on the product between piezoelectric effect and electrochemical redox effect, which is hopeful for the actual dye decomposition. Tourmaline is a natural mineral with spontaneous polarization, which is an ideal piezocatalytic material and is rarely reported in dye decomposition. In this work, after 100 mg tourmaline powder is vibrated for 120 min, the piezocatalytic dye decomposition ratios of rhodamine B (RhB), methylene blue, and methyl orange are ∼95%, ∼46%, and ∼23%, respectively. The corresponding first‐order reaction kinetic values for these three dyes are 0.02681, 0.00639, and 0.00246 min−1, respectively. By adjusting the pH value of the initial RhB solution to 5, the decomposition ratio can reach ∼99% after only 60 min of vibration. In the process of dye decomposition, it is determined that the main active substances are hydroxyl radicals and superoxide radicals via electron spin–resonance spectra test. The spontaneous polarization performance of tourmaline can effectively adsorb dye molecules to promote the catalytic reaction. Natural tourmaline minerals are abundant, low cost, and environmentally friendly making them suitable for large‐scale piezocatalysis of mineral materials. [ABSTRACT FROM AUTHOR]

Tourmaline, a borosilicate, is widespread in many kinds of rocks. Due to its high boron content, tourmaline is quite suitable for in situ B isotope analysis. Tourmaline contains moderate Sr but very low Rb and recent studies show that this mineral has the potential for in situ Sr isotope analysis. Here, we present three new natural tourmaline reference materials GIGT, XJ-1 and XJ-3 for in situ B and Sr isotope measurement by LA-MC-ICP-MS. LA-MC-ICP-MS analyses for these three tourmalines show homogeneous B isotopic compositions with an average δ11B of −12.63 ± 0.51‰ (2SD, n = 74) for GIGT, −11.90 ± 0.64‰ (2SD, n = 78) for XJ-1 and −11.91 ± 0.64‰ (2SD, n = 73) for XJ-3, which agree well with results determined by solution MC-ICP-MS (−12.65 ± 0.12, −11.90 ± 0.24, −11.89 ± 0.19). XJ-1 has relatively high Sr content (∼160 μg g−1), but extremely low Rb/Sr (<0.0005). A total of 176 LA-MC-ICP-MS analyses of XJ-1 yield an average 87Sr/86Sr of 0.70827 ± 0.00021 (2SD), which is in good agreement with the result measured by solution MC-ICP-MS (0.708249 ± 0.000020, 2SD). The homogeneous B isotopes and Sr isotopes suggest that all three tourmalines presented in this study can serve as primary reference materials for in situ B isotope analysis and XJ-1 is suitable to be a monitor reference material for in situ Sr isotope analysis by LA-MC-ICP-MS. [ABSTRACT FROM AUTHOR]

Veloso is one of numerous and poorly documented auriferous deposits of Ouro Preto, the town that symbolises the gold rush in Brazil at the turn of the seventeenth century. We present the results of underground geological mapping, combined with a boron (B) isotopic study of tourmaline, an elusive mineral in the auriferous quartz lode of the historical Veloso deposit. Its lode is characteristically brecciated in a host rock that shows no cataclastic fabric. The host rock is itabirite, a metamorphosed banded iron formation. Tourmaline is essentially dravite and locally occurs as abundant crystals in breccia-cementing pockets of goethite, formed from the oxidation of sulfide minerals. Gold is spatially associated with tourmaline in the goethite-rich pockets. In situ measurements for B isotopes yielded δ11B values in the range of −21 to −9‰. This range is similar to that reported for tourmaline of the Passagem de Mariana deposit, the best documented auriferous lode deposit at the south-eastern edge of the Quadrilátero Ferrífero. The tourmaline B isotopic data reflect auriferous fluids of crustal origin that sourced B from metasedimentary rocks, which may include a non-marine evaporitic component. [ABSTRACT FROM AUTHOR]

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Evidence is presented that the metaconglomerate-hosted Jacobina gold deposits in Brazil represent paleoplacers that became partly remobilized during later metamorphic overprint analogous to Witwatersrand-type deposits elsewhere, notably in South Africa. This includes strong lithological and sedimentological control on the gold, presence of detrital minerals with gold inclusions, and detrital gold particles. Detrital, synsedimentary, and post-depositional pyrite types can be differentiated. Whereas the first two types can be linked to gold accumulation, the latter was associated with gold dispersion. Synsedimentary pyrite has the highest Au content, from which elevated Au concentrations in Archean rivers can be inferred. The nature and extent of post-depositional alteration, mainly in the course of the Paleoproterozoic Orogeny, distinguishes the Jacobina deposits from other Witwatersrand-type gold deposits. Phase equilibria and Zr-in-rutile thermometry indicate peak metamorphic temperatures of ca. 600 °C. Both Mg-chlorite and Fe-chlorite formed in disequilibrium at approximately 280–340 °C during retrograde metamorphism. An igneous signature in the chemistry of some of the tourmaline and the remobilization of gold associated with Fe-oxides, near intrusive rocks, point at a local magmatic influence on the post-depositional mineralization stage. Whether magmatic hydrothermal fluids added Au to the system at that stage remains to be determined. Remobilization during regional metamorphism was insufficient to form substantial ore bodies but led to purification of the initially detrital gold particles that now contain relatively little Ag and Cu and lack Hg. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) is an appropriate choice of analytical tool for analysis of complex minerals because it is rapid, requires little sample preparation, and acquires major and trace element compositional information on all naturally occurring elements at concentrations above their intrinsic levels of detection for the specific analyte material. Tourmaline, a complex borosilicate mineral supergroup, was chosen as a test mineral due to the complexity of its major and minor element composition. Four analytical issues were investigated during project development: (1) the spacing between analytical laser shots to avoid analysis of the recast from previous laser ablations, (2) the efficacy of using a cleaning shot prior to data acquisition, (3) the number of ablations required to collect an average spectrum that is representative of the tourmaline sample, and (4) the effect of spectrometer drift on principal component analysis (PCA) when using the entire LIBS spectra to model the compositional variations within the sample suite. The minimum spacing between locations of analysis was determined to be 800 µ m for the analytical conditions used in this study by examining spectra acquired in a 2×2 grid across a quartz–tourmaline boundary. At a spacing of 100 µ m, twice the diameter of the laser beam, the intensity of the boron I peaks at 249.68 and 249.77 nm was very low in the first location (quartz) but quite high in the fourth location (quartz) due to deposition of tourmaline-composition recast by laser shots in the second and third locations (both on tourmaline). Increasing the distance between locations to 800 µ m ensured that the area analyzed largely avoided the recast layer from previous ablations. Given that the distribution of recast was taken into account, no cleaning shots were collected. PCA score plots calculated using successively larger numbers of spectra from the same sample show that a total of 64 spots, or 16 2×2 grids, are needed to acquire a representative average analysis of tourmaline. Spectrometer drift was recognized in PCA loading plots by a characteristic splitting of element peaks; half the peak indicates positive loading and the other half of the peak indicates negative loading. Drift correction was aligned by placing the Ca II peak at 393.34 nm in the 393.398 bin; this correction eliminated split peaks in loading plots. The resolution of these issues yielded LIBS spectra suitable for multivariate statistical analysis that can be applied to understanding geologic processes. These results contribute to the application of rapid LIBS analysis of complex geomaterials. [ABSTRACT FROM AUTHOR]

The article focuses on the types of natural inclusions found in tourmaline and the minerals in which tourmaline can be included. Topics include the rarity of treatments like enhancement and irradiation, the wide variety of tourmaline species and their sources, and the specific inclusions such as growth tubes and fluid inclusions found in gem-quality tourmaline.

The mineralogical and geochemical features of diamond-bearing tourmaline crystals (schorl-uvite series) from garnet-clinopyroxene rocks of the Kumdy-Kol deposit (Northern Kazakhstan) have been studied in detail. The formation of the main rock-forming minerals (garnet + K-bearing clinopyroxene) occurred in the diamond stability field at 4-6 GPa and 950-1000 °C. Crystallization of K-bearing clinopyroxene at these parameters is possible in the presence of an ultra-potassic fluid or melt formed because of crustal material melting in subduction zones. Tourmaline crystals (up to 1 cm) containing diamond inclusions perform veins crosscutting high-pressure associations. The composition of individual zones varies from schorl to uvite within both a single grain and the sample as a whole. The potassium content in this tourmaline does not exceed 0.1 wt.% K2O, and the isotopic composition of boron δ11B varies from –10 to –15.5 ‰, which significantly differs from the previously established isotopic composition of boron in maruyamaite crystals (δ11B 7.7 ‰ in the core and –1.2 ‰ in the rim) of the same deposit. Analysis of the obtained data on δ11B in the tourmalines from the diamond-grade metamorphic rocks within the Kumdy-Kol deposit suggests the existence of two boron sources that resulted in crystallization of K-bearing tourmaline crystals (maruyamaite-dravite series) and potassium-free tourmalines of the schorl-uvite series.

The controllable electrical and optical properties of two-dimensional tungsten disulfide (WS2) attracted much attention in photocatalysis, but commercial development has been severely restricted by their restacking properties. Surfactant-assisted synthesis techniques can be considered as an effective option to break this bottleneck. In this work, the effect of surfactants including sodium dodecylbenzene sulfonate (SDBS), hexadecyltrimethylammonium bromide (CTAB), and polyvinylpyrrolidone (PVP) on the microstructure of WS2/tourmaline composites prepared by coupled hydrothermal and calcination methods was explored. The WS2 nanosheets were uniformly deposited on the tourmaline surface with the assistance of 1.0 mmol/L SDBS. Meanwhile, WS2/Tour-SDBS exhibited the highest rhodamine B (RhB) degradation activity, which was 1.8 and 2.3 times higher than that of photocatalysts prepared with CTAB and PVP under the same conditions, respectively. This study provides a new tactic for the fabrication of high-performance WS2-based composites.

Thanks to their high chemical and mechanical stability, their diffusion in all types of detrital sediments and their complex structural formula (XY3Z6(T6O18)(BO3)3V3W), tourmalines have attracted strong interest in provenance studies since, from their chemical composition, it is possible to reconstruct the source rocks in ancient sediments. Dravite and schorl, belonging to the alkali subgroup 1, are the most abundant tourmaline species, and they have different Y‐site compositions in the unit cell: dravite has more magnesium, while schorl has a higher iron content. For this reason, it is important to measure the Mg–Fe relative content in order to classify the analysed tourmalines in the dravite–schorl series. Raman spectroscopy is a suitable technique as it allows quick and easy measurements that provide chemical and structural information on tourmalines with a high spatial resolution, thus allowing analysis of small grains that could be found in sediments. In this work, we correlated the relative Mg–Fe content (x = Mg/(Mg + Fe)) in different tourmaline samples from the dravite–schorl series (NaMgxFe1−x3Al6Si6O18BO33OH3OH) with variations in Raman spectrum parameters in order to find a model for quick tourmaline identification useful for provenance studies. The chemical compositions of the analysed tourmalines are obtained by scanning electron microscope coupled with energy‐dispersive spectroscopy (SEM‐EDS). Raman measurements with a portable spectrometer have also been performed in order to evaluate our results for in situ applications. [ABSTRACT FROM AUTHOR]

The article discusses the history and significance of gem mining in southern California, specifically focusing on the pegmatite deposits in San Diego County and southern Riverside County. The region was once a leading source of gem tourmaline and spodumene in the early 20th century, but was later surpassed by discoveries in other parts of the world. However, commercial gem mining has experienced a resurgence in the past two decades, particularly in San Diego County. The article also highlights the production of other gems such as beryl, topaz, garnet, quartz, and apatite in the region. The author emphasizes that gem mining in southern California is still ongoing and new discoveries are being made. [Extracted from the article]

• Tourmaline enhanced the reductive dechlorination efficiency of Desulfitobacterium hafniense. • Tourmaline was able to guide the dechlorination pathway of chlorophenols. • The role of electric field in the process of reductive dechlorination was explored. • Tourmaline had good application prospects in the field of environmental remediation. The dehalogenation of organohalides has been a research hotspot in bioremediation field; however, the influence of tourmaline, a natural ore that can generate spontaneous electric field, on organohalide-respiring bacteria (OHRB) and their dechlorination process is not well known. In this study, the effect and mechanism of tourmaline on the reductive dechlorination of 2,3-dichlorophenol (2,3-DCP) by Desulfitobacterium hafniense DCB-2T were explored. The characterization results confirmed that tourmaline had good stability and the optimal dosage of tourmaline was 2.5 g/L, which shortened the total time required for dechlorination reaction to 72 hr. Besides, tourmaline amendment also increased the proportion of 2-chlorophenol (2-CP) from 18% to 30% of end products, while that of 3-CP decreased correspondingly. The theoretical calculations showed that the bond charge of the ortho -substituted chlorine declined from -0.179 to -0.067, and that of meta -substituted chlorine increased from -0.111 to -0.129, which indicated that the spontaneous electric field of tourmaline affected the charge distribution of 2,3-DCP and was more conducive to the generation of 2-CP. Overall, tourmaline with the spontaneous electric field affected the reductive dechlorination pathway of Desulfitobacterium ,and the tourmaline-OHRB combining system might serve as a novel strategy for the bioremediation of environments polluted with chlorinated phenols. [Display omitted] [ABSTRACT FROM AUTHOR]

An attractive massive green gem material from central China was recently purchased by the authors as 'chrome-pyrophyllite', but proved to be cryptocrystalline Cr-bearing muscovite (fuchsite). The material contains inclusions of ochrous rutile, tourmaline needles, granular quartz, black masses of disordered graphite, and pyrite that is locally altered to black hematite and brownish red lepidocrocite. EDXRF chemical analysis showed the expected major constituents Al, Si and K, as well as minor-to-trace amounts of S, Ba, Ti, Cl, Fe, Cr, V, Rb, Mn and Mg (some of which may be due to inclusions). UV-Vis-NIR spectroscopy showed that the green colour of the muscovite is due to Cr3+ and V3+. The material exhibits whitish blue fluorescence to long-wave UV radiation as well as blue persistent luminescence--neither of which has been documented previously in muscovite--and these features are tentatively assumed to be associated with oxygen vacancies. This new material from China is similar to massive fuchsite from Ethiopia and Myanmar. [ABSTRACT FROM AUTHOR]

Due to their appealing colors, gem quality tourmalines, particularly the blue to green Cu- and Mn-bearing Li-tourmalines known as the Paraíba type, have been of significant interest since their discovery at the end of 1980s. At the same time, the demand of other similar colored tourmalines increased. Most Paraíba-type tourmalines belong to the elbaite species; however, liddicoatite gems can also be found. Recognizing and classifying various tourmaline species, especially these valued Paraíba-type tourmalines, are important for geologists, mineralogists, mineral collectors, and gemologists. This study explores the application of Raman spectroscopy in random crystal orientations to distinguish between the elbaite and liddicoatite tourmaline species. Raman spectra were collected from faceted blue to green Li-tourmalines alongside chemical analysis using EDXRF (Energy Dispersive X-ray Fluorescence), UV-Vis-NIR (Ultraviolet-Visible-Near InfraRed Spectroscopy), and PL (Photoluminescence spectroscopy) to provide comprehensive characterization. The results show that Raman spectroscopy, particularly in the OH stretching region, is a useful tool for differentiating elbaite from liddicoatite, and this identification remains consistent regardless of crystal orientation. The fingerprint region in the Raman spectra, on the other hand, is orientation-dependent and can only differentiate the two species when detected in specific orientations. Furthermore, Paraíba-type tourmalines can be identified by visible-near infrared (Vis-NIR) spectroscopy, although not by Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Study data on dark-colored, bright, and pale pink tourmalines of rare-metal pegmatites from Mt. Okhmylk in the Voron'ya Tundra region are reported. Chemical compositions and parameters of elementary cells are determined for tourmalines. Dark-colored tourmaline I is schörl–olenite, and pink tourmaline corresponds to elbaite–olenite. Studied tourmalines and tourmalines from spodumene pegmatites of other regions are compared. Based on the rare-earth element distribution in tourmalines, they are suggested to have been formed with involvement of high-temperature postmagmatic solutions. Mineral inclusions in schörl–olenite are represented by biotite and magnetite. Mineral inclusions in elbaite–olenite are cassiterite, pollucite, apatite, and tantalite. Tantalite is characterized by higher tantalum and low niobium. In addition, pure manganotantalite is often present in elbaite–olenite, and simpsonite is always observed at contacts between tantalite inclusions and tourmaline. All these data are indicative that albite–spodumene pegmatites of this region were formed with an active role of metasomatic processes. [ABSTRACT FROM AUTHOR]

Crustal rocks in collisional orogens often underwent the metamorphic transition from dehydration to anatexis in response to an increase of geothermal gradients, but it remains obscure how the two types of metamorphism influenced each other. This issue can potentially be addressed by an integrated study of mineralogy and geochemistry for tourmaline in protoliths and their anatectic products. In this paper, we present new results from comprehensive analyses of major-trace elements and B isotopes in tourmaline together with whole-rock Sm–Nd isotopes in well-characterized metapelites and leucocratic dikes from the Himalayan orogen. The leucocratic dikes show whole-rock ε Nd (t) values of −15.7 to −15.4, falling within an ε Nd (t) range of −17.7 to −13.8 for the metapelites. In the metapelites, metamorphic tourmaline (Tur-M) is dravitic and has relatively low δ11B values of −12.0 to −9.0‰. As the metamorphic grade increases, the δ11B values of Tur-M decrease, which is linked to progressive metamorphic dehydration. In the leucocratic dikes, three types of tourmaline are identified by different petrological and geochemical criteria. The tourmaline cores (Tur-LC) are schorlitic and have relatively high δ11B values of −8.7 to −7.7‰, and this type is ascribed to an anatectic origin. The tourmaline rims (Tur-LR) corroding the Tur-LC are dravitic and have relatively high δ11B values of −9.6 to −7.6‰, and this type is attributed to a fluid origin. Another type of anatectic tourmaline (Tur-L) occurs as grains with homogeneous oscillatory zoning that are dravitic and have slightly higher δ11B values of −10.4 to −5.9‰. The anatectic Tur-LC in the leucocratic dikes has higher δ11B values than the metamorphic Tur-M in the metapelites. We attribute this difference to the addition of external fluids with high δ11B values to the metapelite source at the overlying crustal levels. The influxed fluids most likely originated from metamorphic dehydration of lithologically similar metapelites at deeper crustal levels, as evidenced by the Mg-rich characteristics of Tur-L and Tur-LR. The metamorphic fluids would ascend into shallow crustal levels through faults and shear zones, which could not only trigger fluid-fluxed (hydration) melting of the metapelites but also result in fluid activity in later stages. This is further verified by phase equilibrium modelling and model calculation of B geochemical behavior during both metamorphic dehydration and partial melting. On this basis, a spatiotemporally coupled dehydration-hydration melting mechanism is proposed to link the early dehydration metamorphism to the later anatectic metamorphism in the collisional orogen. [ABSTRACT FROM AUTHOR]

Natural Fe2+-rich princivalleite was thermally treated in the air at 700 °C to study crystal-chemical and color variations due to changes in oxidation states of Fe and Mn and atom ordering. Overall, the experimental data (electron microprobe, structural refinement, Mössbauer, infrared, and optical absorption spectroscopy) show that thermal treatment of princivalleite results in an almost total Fe2+ oxidation to Fe3+ and an oxidation of approximately one-third of Mn2+ to Mn3+ along with a minor degree of disorder of Al–Fe–Mn over the Y and Z sites. This process is accompanied by a significant deprotonation of the sample. The YFe and YMn oxidation from + 2 to + 3 yields in a decrease in a-parameter, whereas the increased content of ZFe3+ results in a minor increase in the c-parameter. Optical absorption spectroscopy shows that the faint blue (azure) color of untreated princivalleite is caused by the presence of Fe2+ and the absence of Ti4+. Thermal treatment in air (700 °C) changed the color to dark brown due to the progressive oxidation of Fe2+ to Fe3+ and Mn2+ to Mn3+, as demonstrated by the evolution of optical absorption bands caused by electron transitions in these 3d-cations. However, the most evident result of the thermal treatment of the Fe-rich princivalleite sample is the simultaneous presence of Fe2+, Fe3+, Mn2+, and Mn3+, with a Fe3+/ΣFe and Mn3+/ΣMn ratio of 0.92 and 0.25, respectively. This observation suggests that the oxidation process during the heating experiments was largely controlled by kinetic factors. [ABSTRACT FROM AUTHOR]

The Jian forsterite jade, so named because of its enrichment in end-member forsterite, is a new type of jade found in Ji'an County (Jilin Province, Northeast China). Tourmaline is discovered in Jian forsterite jade deposits and is characterized by magnesium enrichment. In this study, three types of magnesium tourmaline were identified from the pegmatite veins (type 1), the contact zone (type 2), and the tourmaline veins in jade (type 3). The results are shown by the main test methods, such as EPMA, Micro-XRF, and LA-ICP-MS. The substitutions of Fe2+−1Mg2+−1, (□Al3+)−1 (Na+Mg2+)−1, (□Al3+2)−1 (Ca2+R2+2)−1, etc. are inferred by the variations in the major element compositions. From type 1 to type 2 tourmaline, the content of Mg, Sr, and Sn gradually increases, the content of Fe, Zn, K, Mn, Sc, Ga, and Co gradually decreases, the content of Ca initially decreases and then increases, and the content of Na initially increases and then decreases. Type 3 tourmaline has significantly higher Si and Al than the first two types, and the content of the remaining elements lies between the above two types. We propose that tourmalines in Jian forsterite jade deposits are typically of hydrothermal origins and are mainly constrained by magnesium, which is related to the contact metasomatic metamorphism of pegmatite-related hydrothermal fluid with the Jian forsterite jade, and the chemical composition of tourmaline indicates the fluid characteristics of gradual serpentinization of Jian forsterite jade. [ABSTRACT FROM AUTHOR]

In this study, g-C3N4/BiOI/tourmaline composites were synthesized by loading BiOI and tourmaline on g-C3N4 nanofilms using g-C3N4, BiOI, and tourmaline as raw materials, aiming to optimize the photocatalytic degradation of amaranth red dye wastewater (AR). Single-factor experiments were conducted to optimize the degradation process. The findings indicate that a degradation rate of 95.88% can be achieved for AR within 150 min of light exposure, given a g-C3N4/BiOI/tourmaline dosage of 1 g/L, an initial pH level of 3 for the AR, and an initial AR concentration of 10 mg/L. Upon repeating the experiment for five cycles, the composite exhibited 83.10% activity, demonstrating its stability. Various analytical techniques were employed for material characterization: X-ray diffractometry (XRD) to ascertain the crystalline structure, field-emission scanning electron microscopy (FESEM) to evaluate morphology, X-ray photoelectron spectroscopy (XPS) for elemental analysis, ultraviolet–visible diffuse reflectance spectroscopy (UV-vis DRS) for optical properties, and photoluminescence (PL) spectroscopy to analyze the recombination of excited electrons and holes. Free radical masking experiments further elucidated the photocatalytic mechanism, revealing that the primary active species in the degradation process is the superoxide anion (O2−). This research offers a novel approach to address the limitations of n-type metal-free semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

In the Aktyuz-Boordinsky ore district in the Northern Tien Shan, numerous deposits and ore occurrences of gold, rare and rare earth metals and base metals are discovered. Gold deposits are characterized by the presence of a number of metasomatites: beresites, listvenites, K-feldspatites, etc. Many of them are also characterized by quartz-tourmaline gold-bearing metasomatites. A mineralogical and petrographic description of the metasomatic zoning of quartz-tourmaline metasomatites from weakly to highly altered zones is given. Quartz-tourmaline metasomatites form vein-like bodies and metasomatic breccias, where they act as cement, and the fragments can consist of intrusive rock, beresites, K-feldspatites, and listvenites. For the Aktyuz-Boordinsky ore district, quartz-tourmaline metasomatites are a prospecting feature for gold, and for other areas they are a prospecting criterion.