Tourmaline Content Research Articles

Ore formation of the Dayakou emerald deposit (Southwest China) constrained by chemical and boron isotopic composition of tourmaline

The Cretaceous Dayakou emerald deposit (southwest China) hosted in the Neoproterozoic schists and granofels is a magmatic-hydrothermal ore system. In this paper, we present the petrological and geochemical study of tourmaline from the Dayakou deposit, aiming to constrain the source of ore-forming fluid and emerald genesis. Two types of tourmaline, namely type-I formed in emerald-bearing quartz veins and type-II in non-mineralized quartz veins, are distinguished and analyzed in situ for their chemical and boron isotopic compositions. All tourmalines are close to the dravite endmember and belong to the alkali group. The type-I tourmaline has a higher Fe/(Fe + Mg) ratio (0.28–0.47) with Li enrichment (21–227 ppm). The type-II tourmaline, however, shows a lower Fe/(Fe + Mg) ratio (0.14–0.34) with relatively higher Co (2–3 ppm) and REEs (2–21 ppm) content. Boron isotopic composition in tourmaline (δ11B = −15.8‰ to −10.4‰) is closed to the average boron composition of continental crust. The boron isotope variations could be the result of rapid precipitation of tourmaline from a magmatic-hydrothermal fluid or the mixing with a metamorphic fluid. Based on the chemical composition and enrichment in granitophile elements (e.g., Li, Be, Sn) and transition metals (e.g., Ti, V, Cr) in tourmaline, we propose that the Dayakou deposit is dominantly controlled by the fluid-rock interaction between the metamorphic basement and possibly reduced magmatic-hydrothermal fluids. Beryllium is transported as fluoride complex in fluids. Hydrothermal fluids continuously interacted with surrounding rocks to extract Cr, V, and Ca into fluids, resulting in extensive crystallization of fluorine minerals (e.g., fluorite, fluorapatite, etc.) and subsequent destabilization of Be-F complexes. The large amounts of Be, Cr and V enriched in the fluid then combine to form emeralds. The Li, Co, and REEs contents of tourmaline can be used as the exploration indicator to target emerald mineralization in this region.

Geochronology, geochemistry and mineral chemistry of Malayer–Boroujerd–Shazand pegmatite dikes, Sanandaj–Sirjan zone, NW Iran

Pegmatite dikes in the Malayer–Boroujerd–Shazand magmatic complex, located in the Sanandaj-Sirjan zone of the Zagros orogen, are hosted in both granitoid rocks and their contact and regional metamorphic aureoles. In this study, we report the geochronology, geochemistry and mineral chemistry of these pegmatite dikes. The granitoid rocks in the Malayer–Boroujerd–Shazand magmatic suites are mainly monzogranite, quartz diorite, granodiorite and quartz monzonite characterized by metaluminous to peraluminous I-type compositions of the calc-alkaline series and display the geochemical characteristics of volcanic arc granites related to an active continental margin. The pegmatite dikes mainly consist of quartz, feldspar (albite and orthoclase), tourmaline, muscovite and less common biotite and garnet. The tourmaline content in the igneous-hosted pegmatite dikes is higher than those of metamorphic rocks, whereas the muscovite content is lower in the igneous-hosted pegmatite dikes. The K/Rb ratio and the Rb content of pegmatite dikes and their minerals (K-feldspar and muscovite) indicate that they are less evolved. Pegmatite dikes display a typical calc-alkaline affinity of I-type granites and are classified as peraluminous Lithium-Caesium-Tantalum (LCT) family (barren sub-type) to muscovite class. The tourmaline is a schorl-foitite type, which is common in the early crystallization stage of less evolved pegmatites. U–Pb zircon dating of the Boroujerd and Shazand pegmatite dikes yield weighted mean 206Pb/238U ages of 160.2 ± 1.8 and 121.8 ± 1.5 Ma, respectively. In contrast, U–Pb zircon dating of the Malayer pegmatite dike gives a mean 206Pb/238U age of 43.2 ± 1.5 Ma. Our new geochronological data indicate that the first group of pegmatite dikes (older pegmatite dikes) in the Boroujerd district (160.2 ± 1.8 Ma) shows an overlap with the main and first magmatic episode in the Sanandaj–Sirjan zone during Jurassic times, simultaneous with the Middle Cimmerian Orogenic phase, and formed during the subduction initiation. The second group of pegmatite dikes in the Shazand district (121.8 ± 1.5 Ma) formed in the Early Cretaceous and shows a temporal overlap with previously reported ages (ca. 130–114 Ma) during the early Alpine tectonic movements (Late Cimmerian Orogenic phase). Finally, the younger group of pegmatite dikes in the Malayer district (43.2 ± 1.5 Ma) formed in the Eocene overlapping with previously reported ages (ca. 34–52 Ma) which is equivalent to the Laramian phase. These data reveal that the magmatism in the Malayer–Boroujerd–Shazand magmatic complex started in the Early-Middle Jurassic resembling adjacent areas in the Sanandaj–Sirjan zone (e.g., Hamedan region) by melting of crustal protoliths in a subduction tectonic setting. The second and third groups of pegmatite dikes formed during the late subduction to syn-collisional process, respectively. These pegmatite generation marked the subduction initiation to syn-collisional span in the region. The zircon geochemistry (negative Ce anomalies and positive Eu anomalies) is indicative of the relatively oxidized conditions of the parent magma and shows characteristics of continental crust zircon.

The Mg/(Fe + Mg) ratio and the Ti and A site contents of tourmaline as promising indicators of granitic magma evolution

In the recent past, important research has shown how tourmaline can be used as a petrogenetic indicator in pegmatite rocks and related mineralization. Previous studies have demonstrated that tourmaline composition may be a useful guide to ascertain the degree of evolution and oxygen fugacity of host granitic rocks from the Variscan orogen in the Central Iberian Zone (CIZ). Following those promising preliminary conclusions, we have investigated whether these results hold for tourmaline-bearing granitic rocks from other geotectonic contexts, enlarging our scope to include whole-rock stable isotope analyses. The data collected so far has shown that, whereas most tourmaline components and component ratios seem essentially impervious to granitic magma composition and oxygen fugacity, there are a few exceptions, such as the Mg/(Mg + Fe) ratio and Ti contents of tourmaline that show clear variation with the degree of evolution and oxygen fugacity of the host granitic rocks. From both mineralogical and petrological points of view, it seems that these compositional features in tourmaline may be used as indicators of the degree of evolution and of specific characteristics of the granitic magmas that produced them.

WITHDRAWN: Enhanced far infrared radiation properties of functional ceramics derived from iron ore tailings incorporating tourmaline particles

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Performance evaluation of tourmaline modified asphalt mixture based on grey target decision method

Tourmaline modified asphalt mixture has the air purification effect and is an excellent low-carbon road material. However, previous studies mainly focused on the improvement of road performance for tourmaline modified asphalt mixture. There were few studies on its comprehensive performance evaluation. In order to further promote the application of tourmaline in the field of modified asphalt mixtures, tourmaline modified asphalt mixture was prepared. The comprehensive performance evaluation system for tourmaline modified asphalt mixture was established based on the grey target decision method. Based on two mixing methods, the road performance of tourmaline modified asphalt mixture were systematically analyzed, the comprehensive performance of tourmaline modified asphalt mixture was evaluated, the suitable content of tourmaline in the modified asphalt mixture was determined. The results show that the comprehensive performance evaluation system based on grey target decision method has good reliability and practicability. The comprehensive performance of tourmaline modified asphalt mixture achieves its best with 10% tourmaline.

Enhanced mechanical properties of 3 mol% Y2O3 stabilized tetragonal ZrO2 incorporating tourmaline particles

The current study reports on the improvement of mechanical properties of 3 mol% Y2O3 stabilized tetragonal ZrO2 (3Y-TZP) by introduction of tourmaline through ball milling and subsequent densification by pressureless sintering at 800, 1200, 1300, 1400 °C. Findings demonstrate that no matter which sintering temperature the 3Y-TZP ceramic containing 2 wt% tourmaline reach a maximum value in flexural strength and fracture toughness as compared to other composite ceramics. As the tourmaline content is 2 wt% and the sintering temperature is 1300 °C, the flexural strength and fracture toughness of the composite ceramics are the highest, increases of 36.2% and 36.6% over plain 3Y-TZP ceramic respectively. The unique microstructure was systematically investigated through X-ray diffraction, scanning electron microscopy, energy dispersive spectrum, and flourier transform-infrared. The strengthening and toughening mechanism of tourmaline in 3Y-TZP ceramic were also discussed.

Tourmaline activated persulfate for degradation of Sirius Türkis GL 01

The high Fe2+ content of tourmaline (TM) has potential of activating a persulfate reaction. However, information pertaining to using TM as an activator in persulfate oxidation process is currently unavailable. In this study, powdered TM was used to activate persulfate (PS) oxidation for decolorization synthetic direct azo dye, Sirius Turkis GL 01 (STGL). Findings revealed that decolorization was significantly enhanced by TM/PS combined with ultrasound. A suitable oxidation condition for removal true color was TM 1.5 g/L, PS 5 × 10−4 M, US 106 W/cm2 (20 min sonication at 20 kHz), and initial pH 6.0, which could completely remove the color and COD of 40 mg/L STGL after 20 min treatment. Oxidation condition under higher TM dosage with higher sonication power is beneficial for generation of sulfate radicals, consequently, promoting the oxidation performance of TM/PS process. Results clearly indicated that Fe-tourmaline, can be potentially used to activate PS oxidation for effective decolorization of wastewater containing direct azo dyes.

Mineralogy of the Koktokay No. 3 pegmatite, Altai, NW China: implications for evolution and melt–fluid processes of rare-metal pegmatites

The Koktokay No. 3 pegmatite is the largest Li-Be-Nb-Ta-Cs pegmatitic rare-metal deposit of the Chinese Altai orogenic belt, and is famous for its concentric ring zonation pattern (nine internal zones) and rare-metal reserves. In this paper, we present the results of major and trace element analysis for garnet, tourmaline, and beryl from the outer to inner zones of the No. 3 pegmatite. From previous studies on tourmaline and beryl, potential tracers of the degree of pegmatite evolution could be found by comparing with accepted indicators and evolutionary trends from the outer to inner zones of this pegmatite. The Sc, Y, Li, Ta contents and Y/Ho value of garnet, together with the Ti, Ca, Na, Pb, Bi and REE contents of tourmaline, and the Fe, Ga and Rb concentrations of beryl could be possible tracers of the degree of evolution of pegmatites. The textures and internal structures (homogeneity, oscillatory pattern, heterogeneous rims, replacement structures) of minerals in the pegmatite suggest that the rock underwent (1) rapid undercooling and crystallization after emplacement, resulting in the formation of an unidirectional solidification texture (UST), and then (2) became relatively stable, forming coarse crystals in outer zones, and finally (3) experienced disequilibrium crystallization, leading to the formation of complex internal structures of minerals in the inner zones, mainly caused by exsolution of more fluid and the formation of immiscible melts with different alkali contents. The evolutionary trend and the internal structures of tourmaline and beryl indicate that the formation of the Koktokay No. 3 pegmatite was controlled mainly by fractional crystallization. The convex tetrad effect, non-CHARAC Y/Ho values, and extreme Eu depletion of garnet suggest that immiscibility, which is a significant mechanism during the formation of the No. 3 pegmatite, occurred during emplacement. The differences in composition and internal structures of the minerals between the outer and inner zones of the No. 3 pegmatite suggest that there was an abrupt change, during transition from the melt stage to the melt–fluid stage, resulting from a decompression event, which led to the exsolution of the fluid and initiated the Li-Ta-Cs deposition in the pegmatite.

Properties of La0.9Sr0.1MnO3 and tourmaline compound catalytic materials for methane combustion

A novel catalytic material La0.9Sr0.1MnO3 and tourmaline compound catalytic material was synthesized in the base of traditional catalytic material La0.9Sr0.1MnO3 which exhibited excellent catalytic activity for methane combustion. Different contents of tourmaline were added to give a series of La0.9Sr0.1MnO3 and tourmaline catalytic material through a sol-gel method. Samples above were characterized and analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET), temperature programmed reduction (TPR), catalytic activity test and contact angle test. The as-prepared sample with 2% (m/m) tourmaline showed good homogeneity surface morphology and displayed the optimal catalytic activity. The light-off temperature reduced by 10 °C and the T90 decreased by 15 °C. In addition, the mechanism of the reinforcement of catalytic activity was explored.

Research on Proportioning Design of Tourmaline Modified Asphalt Mixture

In order to study the effect of tourmaline on asphalt mixture design indexes, the optimal asphalt content of modified asphalt mixture with different contents of tourmaline were determined through Marshall Test, and the variation of optimal asphalt content caused by tourmaline was analyzed. The effect of tourmaline on density, porosity, VMA, VFA, stability, flow value were studied. Under the guidance of surface theory and mortar theory respectively, the Marshall Volume indicators of tourmaline modified asphalt mixture were analyzed comparatively. A mix design method for asphalt mixture modified inorganic powder is recommended.

Preparation and Photocatalytic Activity of TiO<sub>2</sub>/Tourmaline Composite Catalyst

TiO2/tourmaline composite photocatalyst was prepared by sol-gel method using tetrabutyl orthotitanate (Ti (OC4H9)4) as a precursor. As a comparison, pure TiO2 was prepared at the same experimental conditons without the addition of tourmaline. The obtained composite photocatalyst was characterized by X-Ray diffraction (XRD) and scanning electron microscope (SEM) and its photocatalytic activity was also investigated through the photodiscoloration of methyl orange (MO) under UV irradiation. The XRD results indicated that, in the composite photocatalyst, TiO2 existed in the form of anatase and rutile, with the sintering temperature and tourmaline content increasing, the anatase phase trended to the transformation to rutile phase. The SEM results revealed that the nanosized particles of TiO2 were well dispersed and immobilized on the surface of tourmaline, especially for the sample with 2% tourmaline content. Compared with pure TiO2, the composite photocatalyst exhibited a higher photocatalytic activity. When the pure TiO2 was used as the photocatalyst, the MO discoloration ratio only reached 55%. However, the MO discoloration ratio could approach 100% in presence of TiO2/tourmaline composit photocatalyst under the same conditions. The effects of tourmaline content and sintering temperature on the photocatalytic activity of the composite were studied in this work and the results suggested that the sample with 2% tourmaline content and sintered at the temperature of 550°C exhibited the best photocatalytic activity. Finally, the possible mechanism for the photodiscoloration of MO was put forward.

New Technology of Preparation of TiO<sub>2</sub>/Tourmaline by Dry Coated Method and its Application in Coating

The high whiteness tourmaline composite powder was prepared with powder coating method in which TiO2 as the coating agent and the stearic acid as the coupling agent. The powder coating method system theoretical research was improved to aim at resolving the tourmaline’s limited applications in environmental health field due to the darker color. Theory and test results show that when the tourmaline and the coating agent mass ratio of about 2:1, the best results by scanning electron microscopy indicating that the tourmaline composite powder particle size prepared of this ratio is uniform with the composite powder whiteness of 74.5% which is 23.5% higher than building whiteness of the direct coating agent for mechanical mixing with tourmaline powder. After the composite powder was used to prepare the coating, the results show that the whiteness is 87.1% after formatting coating and negative ions incremental release over the 800 ions/cm3 when the content of tourmaline is 11%.

Research on Aging Properties of Tourmaline Modified Asphalt

Aging properties of tourmaline modified asphalt prepared by melt blending were studied. The change laws of aging properties of asphalt caused by different types and contents of tourmaline were studied systematically by rotated thin film oven tests (RTFOT), in which the indices of aged residues such as softening point, penetration and ductility were tested. The results showed that the anti-aging performance of asphalt was improved effectually with addition of tourmaline, the ratio of residual penetration and ductility increased, and the softening point increment of aged asphalt decreased. The improvement of anti-aging performance of asphalt reduced with the increasing mixing amount of tourmaline. Tourmaline anion powder (5000ions) was recommended to improve the anti-aging performance of asphalt.

Antibacterial and superhydrophilic electrospun polyurethane nanocomposite fibers containing tourmaline nanoparticles

This paper describes a one-step fabrication of tourmaline (TM) nanoparticles (NPs)-decorated polyurethane (PU) composite nanofibers with superhydrophilic and antibacterial properties. The physico-chemical properties of the prepared samples were characterized by different characterization techniques. FESEM and TEM images confirmed the presence of well-dispersed TM NPs in/on PU nanofibers. The incorporation and homogeneous dispersion of 3wt% TM NPs in PU exhibited an increase in tensile strength and modulus of 75% and 87%, respectively from those of the neat PU. All TM/PU composite mats showed improved hydrophilicity compared to neat PU mat, and a superhydrophilic surface with a contact angle of 13° was obtained at 5wt% TM content. FTIR spectra confirmed the interaction of TM NPs to PU matrix through hydrogen bonding. Bacterial tests showed high zone inhibition for both Escherichia coli (Gram-negative) and Enterococci (Gram-positive) using the TM/PU composite mats with increasing efficiency as with the increase of TM NP content. The present TM/PU composite mat, which has improved mechanical properties, superhydrophilic surface, and good antibacterial properties, may be a potential candidate as an antibacterial material, in the field of health-protection textile and water filtration.

Preparation and properties of multifunctional nylon 6 composite material

We considered polyamide 6 as a base material for a composite and added improved tourmaline and carbon fiber to manufacture a material that could release negative ions and resist electromagnetic waves. Through Fourier transform infrared spectroscopy and thermogravimetric analyses, we verified that the improved tourmaline could disperse homogeneously in the base material, whose thermal properties improved as the content of tourmaline increased. Scanning electron microscopy demonstrated that the added tourmaline and carbon fiber complemented the conductive network of the composite material. A negative ion detector and an infrared thermal imaging system both revealed that with an appropriate tourmaline content, the negative ion release properties of the composite material could reach 2020 units cm−3 with a difference in temperature of up to 7.54°C. Analyses by a four-point probe low-resistance tester and electromagnetic wave shielding effectiveness tester demonstrated that the osmotic concentration was approximately 4%, and the surface resistivity was high, up to 1.04 × 107 Ω cm−1, reaching the range of static dissipative materials (106–1012 Ω cm−1). The maximum electromagnetic wave shielding effectiveness was as high as 30 dB MHz−1.

Study of Fibre Tourmaline/PVA Nanofibre Prepared by Electrospinning

This is the first time, prepared fiber-tourmaline nano powder use of Fiber-tourmaline. Vinyl acetate, fiber-tourmaline nano powder and EDTA as raw material, use micro-polymer chemistry laboratory equipment, preparation of the fiber-tourmaline/PVA spinning solution. The first time, prepared Fiber-tourmaline/PVA composite nanofibers, use of micro-polymer processing equipment—— electrospinning machine. The samples were characterized and tested the performance of its release anions. Analysis the effects of the fiber-tourmaline powder quantity on the properties of nano-fibers, and to explore the best tourmaline content.

The tourmaline-bearing granite pluton of Bodmin (Cornwall, UK): magnetic fabric study and regional inference

The magnetic fabrics and microstructures of the Variscan granite pluton of Bodmin (Cornwall) have been studied. Its low susceptibility magnitude, consistent with its lack of magnetite, comes from biotite and tourmaline. As the magneto-crystalline behaviour of tourmaline is ‘inverse’ compared with that of the phyllosilicates, the magnetic fabric was remeasured after heating the specimens to enhance the biotite magnetic signal by the growth of mimetic magnetite. The roughly similar magnetic fabrics before and after heating demonstrate that the effect of tourmaline is not important as long as the tourmaline content does not exceed that of the phyllosilicates. Regionally, this study reveals a well-defined NNW trend of the magnetic lineations with opposite plunges on each side of a separation line crossing the pluton centre. This pattern, very similar to that documented in the nearby Carnmenellis pluton, is ascribed to unroofing during emplacement. It agrees with the late to post-magmatic NW stretch that characterizes the Devonian to Carboniferous formations located to the north of this region, the thrust-and-fold structure of which is attributed to southward compression. We conclude that syntectonic emplacement may have characterized the whole Cornubian batholith at the very end of the Variscan orogeny in Cornwall.

Structure and properties of regenerated cellulose/tourmaline nanocrystal composite films

AbstractNanocomposite films were successfully prepared from cellulose and tourmaline nanocrystals with mean diameters of 70 nm in a 1.5 M NaOH/0.65 M thiourea aqueous solution by coagulation with 5 wt % CaCl2 and then a 3 wt % HCl aqueous solution for 2 min. The structure and properties of the composite films were characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and tensile testing. The results indicated that the tourmaline nanocrystals were dispersed in a cellulose matrix, maintaining the original structure of the nanocrystals in the composite films. The loss peaks (tan δ) in the DMA spectra and the decomposition temperatures in the DSC curves of the composite films were significantly shifted toward low temperatures, suggesting that the nanocrystals broke the partial intermolecular hydrogen bonds of cellulose, and this led to a reduction in the thermal stability. However, the nanocomposite films exhibited a homogeneous structure and dispersion of the nanocrystals. When the tourmaline content was in the range of 4–8 wt %, the composite films possessed good tensile strength (92–107 MPa) and exhibited obvious antibacterial action against Staphylococcus aureus. This work provides a potential way of preparing functional composite films or fibers from cellulose and nanoinorganic particles with NaOH/thiourea aqueous solutions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 367–373, 2004

Garnet, tourmaline and muscovite-bearing leucogranites, gneisses and migmatites of the Higher Himalayas from Zanskar, Kulu, Lahoul and Kashmir

Summary Approximately 30–50% of the map area of the Central Crystalline Complex of the Higher Himalayas in Zanskar, Kulu, Lahoul and Kishtwar-Kashmir (NW India) is composed of Miocene leucogranites intruding metamorphic basement rocks. Ultrametamorphism at deeper crustal levels resulted in in situ anatexis, migmitization and lit-par-lit intrusions or stromatic layering within high-grade metasedimentary rocks. Garnet, tourmaline and muscovite-bearing granites locally contain biotite, apatite or kyanite. Leucogranites at higher crustal levels are associated with a widespread network of anastomosing dykes and sills with high tourmaline content. Rare-earth-element (REE) abundances are relatively low. Garnets are compositionally variable and are usually unzoned. Extremely high 87 Sr/ 86 Sr initial ratios of leucogranites (0.755–0.769) indicate a crustal anatectic origin while the wide range of Sr initial ratios can be explained by melting of a variety of metasedimentary rocks of the subducting Indian Shield. Radiometric ages of Himalayan leucogranites (28–12 Ma) follow closely in time a thermal peak of metamorphism (40–25 Ma). Inversion of metamorphic isograds during large-scale crustal subduction along several major thrust zones in the Higher Himalayas followed immediately after generation of the leucogranites. The leucogranites are interpreted as anatectic melts of high-grade metamorphic crystalline basement, generated at depth by residual (Barrovian) heat with a large amount of volatile and fluid flux. Frictional heating along the N-dipping Main Central Thrust is not considered a major source of heat for generation of the leucogranites.

Discriminant analyses of heavy minerals in beach and dune sediments of the Outer Banks barrier, North Carolina

A stepwise multiple discriminant-function analysis was used to evaluate the effectiveness in differentiating between heavy-mineral assemblages of the foreshore, berm, and dune subenvironments along the Outer Banks barrier island system of North Carolina. Samples from each of the three subenvironments were collected from 23 regularly spaced localities along the barrier island system. Ten heavy-mineral variables were determined for each sample. The discriminant method using heavy-mineral analyses resulted in extremely limited differentiation between these three subenvironments. The discriminant analyses were performed in two designs. The first analysis, using a total of 69 samples from all three subenvironments, yielded a correct assignment of 43% of the samples, based on their tourmaline content. A second analysis consisted of three separate discriminant analyses of the heavy-mineral assemblages, differentiating the following pairs of subenvironments: (1) foreshore and dune, (2) foreshore and berm, and (3) berm and dune. A total of 74% of the samples were correctly assigned in the analysis of foreshore and dune subenvironments, based on amphibole and tourmaline as significant discriminators; 63% of the samples were correctly assigned in the foreshore and berm subenvironments, based on tourmaline as the most significant discriminator; and 0% of the samples were assigned in the berm and dune subenvironments where none of the heavy-mineral variables was determined as a significant discriminator. Thus, the discriminant-function analysis recorded a general lack of success in differentiating between the heavy minerals of the three subenvironments. More specifically, our study suggests that equidimensional heavy minerals, and to some degree elongate heavy minerals, are not useful for discriminating between subenvironments in the nearshore area.