Search Results (1,310)

CaO-Al₂O₃-Ce₂O₃ is a potential new-type basic metallurgical slag system for rare earth steel. To investigate the effects of CaF₂ on the melting point and equilibrium phase types of this slag system, the phase equilibrium relationships and extent of the liquid phase region of CaO-Al₂O₃-Ce₂O₃-CaF₂ slag system at 1300 °C, 1400 °C, and 1500 °C in C/CO were determined by the high-temperature phase equilibrium experiment, Scanning Electron Microscope-Energy Dispersive X-ray Spectrometer (SEM-EDX) and X-ray Diffraction (XRD), and the isothermal phase diagram was plotted. The experimental results show that within the composition range in this study, the slag system has five, seven, and six liquid–solid equilibrium coexistence regions at 1300 °C, 1400 °C, and 1500 °C. The involved multiphase equilibrium regions include five two-phase regions (i.e., Liquid + CaO, Liquid + CaO·2Al₂O₃, Liquid + 2CaO·Al₂O₃·Ce₂O₃, Liquid + 2CaO·3Al₂O₃·Ce₂O₃, Liquid + 11CaO·7Al₂O₃·CaF₂), 4 three-phase regions (i.e., Liquid + CaO + 2CaO·Al₂O₃·Ce₂O₃, Liquid + 11CaO·7Al₂O₃·CaF₂ + 2CaO·Al₂O₃·Ce₂O₃, Liquid + CaO·2Al₂O₃ + 2CaO·3Al₂O₃·Ce₂O₃, Liquid + 11CaO·7Al₂O₃·CaF₂ + 2CaO·3Al₂O₃·Ce₂O₃), and 1 four-phase region (i.e., Liquid + CaO + 11CaO·7Al₂O₃·CaF₂ + 2CaO·Al₂O₃·Ce₂O₃). Meanwhile, based on liquid phase compositions under liquid–solid multiphase equilibrium, the slag system’s liquid phase ranges at the experimental temperatures were determined as follows: at 1300 °C: w(CaO)/w(Al₂O₃) = 0.42~0.92, w(Ce₂O₃) = 1.63%~8.02%, w(CaF₂) = 9.17%~21.46%; 1400 °C: 0.28~1.18, 0.9%~12.62%, 1.04%~23.34%, respectively; 1500 °C: 0.23~1.21, 0~14.42%, 0~26.32%, respectively. Full article

Ladle slag (LF slag) is a by-product of secondary steelmaking that presents unique valorization challenges compared to BOF or EAF slags due to its distinctive chemical composition (high Al₂O₃ and CaO content) and uncontrolled hydraulic activity. While other steelmaking slags can be reused as supplementary cementitious materials or aggregates, LF slag is predominantly landfilled, with over 2 million tons discarded annually in Europe alone. This study introduces a novel pyrometallurgical valorization strategy that, unlike conventional approaches focused solely on mineral recovery, simultaneously recovers both metallic and mineral value through aluminothermic reduction. This process utilizes end-of-waste aluminum scrap rather than virgin materials to reduce Fe and Si oxides, creating a circular economy solution that addresses two waste streams simultaneously. The process generates two valuable products with low liquidus temperatures: a ferrosilicon alloy (FeSi15-50 grade) and a residual oxide rich in calcium and magnesium aluminates suitable for cementitious or ceramic applications. Through the integration of FactSage thermodynamic simulations with experimental validation, it is possible to predict and control phase evolution during equilibrium cooling, an approach not previously applied to LF slag valorization. Experimental validation using industrial slags confirms the theoretical predictions and demonstrates the process operates in a near-energy-neutral, self-sustaining mode by recovering both chemical and sensible thermal energy (50–100 kWh per ton of slag). This represents approximately 90% lower energy consumption compared to conventional ferrosilicon production. The work provides a comprehensive and scalable approach to transform a problematic waste material into valuable products, supporting circular economy principles and low-carbon metallurgy objectives. Full article

For optimizing the operational efficiency and productivity within blast furnace processes, a profound understanding of the viscous flow characteristics of CaO–SiO₂–MgO–Al₂O₃–B₂O₃ slag systems is of paramount importance. In this study, we conducted a comprehensive investigation into the influence of the CaO/SiO₂ and MgO/Al₂O₃ ratios on the viscosity, break point temperature (T_Br), and activation energy (E_η) of low boron-bearing high-alumina slag. Concurrently, we elucidated the underlying mechanisms through which these ratios affect the viscous behavior of the slag by employing a combination of analytical techniques, including X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and thermodynamic modeling using the Factsage software. The experimental findings reveal that, as the CaO/SiO₂ ratio increases from 1.10 to 1.30, the slag viscosity at 1773 K decreases from 0.316 Pa·s to 0.227 Pa·s, while both the T_Br and E_η exhibit an upward trend, rising from 1534 K and 117.01 kJ·mol⁻¹ to 1583 K and 182.86 kJ·mol⁻¹, respectively. Conversely, an elevation in the MgO/Al₂O₃ ratio from 0.40 to 0.65 results in a reduction in slag viscosity at 1773 K from 0.290 Pa·s to 0.208 Pa·s, accompanied by a decrease in T_Br from 1567 K to 1542 K. The observed deterioration in slag flow properties can be attributed to an enhanced polymerization degree of complex viscous structural units within the slag matrix. Ultimately, our study identifies that an optimal viscous performance of the slag is achieved when the CaO/SiO₂ ratio is maintained at 1.25 and the MgO/Al₂O₃ ratio is maintained at 0.55, providing valuable insights for the rational design and control of blast furnace slag systems. Full article

In this work, molecular and elemental spectroscopic analyses were carried out on the preparation base, the paintings, the repaintings, and the gilding of an 18th century sacred sculpture of Our Lady found on Anhatomirim Island, where the Santa Cruz fortress was built in 1739 in the state of Santa Catarina, southern Brazil. The preparation base of the sculpture was characterized as gypsum (calcium sulfate dihydrate, (CaSO₄.2H₂O) [µ-Raman, SEM-EDS], applied directly to the wooden support. The blue paint comprised a mixture of Prussian blue (Fe₄[Fe(CN)₆]₃) and ultramarine (Na_xAl₆Si₆O₂₄S_x) [µ-Raman, FTIR, SEM-EDS]; hematite (Fe₂O₃) was identified in the brown paint [µ-Raman, SEM-EDS]; and the white paint consisted of lead white (2 PbCO₃·Pb(OH)₂) [µ-Raman, FTIR, SEM-EDS]. Repainted areas were identified by the presence of lithopone (ZnS + BaSO₄) [µ-Raman, SEM-EDS, FTIR], likely resulting from later interventions. In the gilded areas, gold was identified along with traces of iron [SEM-EDS], indicating a lower-quality gilding compared to, for example, silver alloys. Lead white was also identified in the polychrome areas, where it served to produce different tones in the painting. FTIR analyses revealed traces of aged oil used as a binder in the older layers. Mineral oil was detected in some samples, which may indicate that wax was used as a protective layer on the sculpture. The results will assist professionals in the iconographic characterization of the sacred image of Our Lady and in the conservation and restoration processes based on the identified constituent materials. Full article

Highly developed countries generate large volumes of industrial waste, the type and quantity of which are strongly linked to the characteristics of the industries that produce it. Industrial waste can adversely affect the environment, so its disposal and management are a major challenge. Understanding the characteristics of a given waste type (e.g., its chemical and phase composition, technical parameters and likelihood of releasing constituents into aquatic and soil environments) allows its potential economic applications to be determined. A simple application of mineral waste is in the production of artificial aggregates, which are increasingly used as a substitute for natural aggregates. In Poland, artificial aggregates are widely produced from metallurgical waste from steel and non-ferrous metallurgy, which may contain numerous components that are potentially environmentally damaging. Depending on their occurrence form (i.e., mineral composition), these contaminants have varying potential to be released into aquatic and soil environments. This study presents the results of mineral and chemical composition analyses and leachability tests conducted on aggregates produced from metallurgical waste, including slags from blast furnaces, steelmaking, Zn and Pb production, and Ni production. The studied aggregates are characterised by chemical and phase composition differences, resulting from the type of slag from which they originate. The chemical composition of blast furnace slag is dominated by CaO, SiO₂, Fe₂O₃, and MgO; steelmaking slag by CaO, Fe₂O₃, and SiO₂; Zn and Pb production slag by SiO₂, Fe₂O₃, SO₃, and CaO; and Ni production slag by SiO₂, Fe₂O₃, CaO, and Al₂O₃. The phase composition of all the tested aggregates is dominated by silicates resistant to leaching (weathering), which results in low levels of Al, Ca, Cr, Mn, Zn, Pb, Cu, As, Sr and Ni leaching, not exceeding 1.6%. Full article

The appropriate selection of renovation plaster properties is essential for ensuring the durability and effectiveness of conservation works. This study focused on the design and characterization of cement-based renovation mortars modified with synthetic zeolites with different Si/Al ratios. It was assumed that high-silica zeolites would provide more favorable mechanical and hygric performance than low-silica types. Owing to their porous structure and pozzolanic reactivity, zeolites proved to be effective additives, enhancing both the microstructure and functionality of the mortars. The modified mixtures exhibited increased total porosity, higher capillary absorption, and improved moisture transport compared with the reference mortar based on CEM I 52.5R. Dynamic vapor sorption tests confirmed that the zeolite-containing mortars achieved Moisture Buffer Values (MBV) above 2.0 g/m², which corresponds to the “excellent” moisture buffering class. Electrical resistivity measurements further demonstrated the relationship between denser microstructure and enhanced durability. At the frequency of 10 kHz, the electrical resistivity of the reference mortar reached 43,858 Ω·m, while mortars with 15% ZSM-5 and 15% Na-A achieved 62,110 Ω·m and 21,737 Ω·m. These results show that the addition of high-silica zeolite promotes the formation of a denser and more insulating matrix, highlighting the potential of this method for non-destructive quality assessment. The best overall performance was observed in mortars containing the high-silica zeolite ZSM-5. A 35% replacement of cement with ZSM-5 increased compressive strength by 10.5% compared with the reference mortar R (4.3 MPa). Frost resistance tests showed minimal mass loss (0.03% at 15% and 1.79% at 35% replacement), and ZSM-5 mortars also maintained integrity under salt crystallization. These improvements were attributed to the reaction of reactive SiO₂ and Al₂O₃ from the zeolites with Ca(OH)₂, leading to the formation of additional C-S-H. A higher Si/Al ratio promoted a denser, fibrous C-S-H morphology, as confirmed by SEM, which explains the improved strength and durability of mortars modified with ZSM-5. Full article

The presence of impurities such as Ca, Mg, and Al during the precipitation of rare earths (REs) using ammonium bicarbonate directly affects product purity. It is necessary to optimize precipitation methods and conditions to improve the separation efficiency between REs and impurities. In this study, RE (La and Ce) ions were precipitated using ammonium bicarbonate solution, and the separation efficiency of REs from Al, Fe, Ca, and Mg ions was investigated with or without the addition of triammonium citrate (TAC). The results showed that as long as the precipitation yield of REs was controlled below 94%, Ca and Mg ions would not enter the precipitation in the absence of other impurities, and the purity of the obtained rare earth oxides (RE₂O₃) was close to 100%. The presence of Al and Fe impurities would reduce the separation efficiency of REs from Ca and Mg. Therefore, Al and Fe must be separated before the precipitation of REs. First, Fe was completely precipitated by controlling the pH value to 4.12. Then, by filtering out the isolation and adjusting the pH value to 4.6, approximately 84% of Al³⁺ was precipitated, with a loss of REs of about 6%. Finally, the pH value was increased to 6.43, and REs were completely precipitated, yielding rare earth carbonate. The RE₂O₃ purity of its calcination product was 97.8% with Al and Mg contents of 1.05% and 0.21%, respectively, and no Ca or Fe was detected. This indicated that Mg can enter the product by co-precipitation with Al. To address this, a small amount of TAC was added during the pre-removal of Fe and Al to facilitate the complete removal of Al. By controlling the precipitation yield of REs at 94%, the purity of the final RE₂O₃ reached 99.6% with an Al content of 0.09%. Furthermore, using a continuous precipitation crystallization method, RE₂O₃ purity can be achieved at 99.8% with an Al content of 0.06%. Full article

The crystal structure of kuliokite-(Y), Y₄Al(SiO₄)₂(OH)₂F₅, has been re-investigated using the material from the type locality the Ploskaya Mt, Kola peninsula, Russian Arctic. It has been shown that in contrast to previous studies, the mineral is monoclinic, Im, with a = 4.3213(1), b = 14.8123(6), c = 8.6857(3) Å, β = 102.872(4)°, and V = 541.99(3) ų. The crystal structure was solved and refined to R₁ = 0.030 on the basis of 3202 unique observed reflections. The average chemical composition determined by electron microprobe analysis is (Y_2.96Yb_0.49Er_0.27Dy_0.13Tm_0.07Lu_0.05Ho_0.05Gd_0.01Ca_0.01)_Σ4.04Al_0.92Si_2.04O₈-[(OH)_2.61F_4.42]_Σ7.03; the idealized formula is (Y,Yb,Er)₄Al[SiO₄]₂(OH)_2.5F_4.5. The crystal structure of kuliokite-(Y) contains two symmetrically independent Y sites, Y1 and Y2, coordinated by eight and seven X anions, respectively (X = O, F). The coordination polyhedra can be described as a distorted square antiprism and a distorted pentagonal bipyramid, respectively. The refinement of site occupancies indicated that the mineral represents a rare case of HREE fractionation among two cation sites driven by their coordination numbers and geometry. In agreement with the lanthanide contraction, HREEs are selectively incorporated into the Y2 site with a smaller coordination number and tighter coordination environment. The strongest building unit of the structure is the [AlX₂(SiO₄)₂] chain of corner-sharing AlX₆ octahedra and SiO₄ tetrahedra running along the a axis. The chains have their planes oriented parallel to (001). The Y atoms are located in between the chains, along with the F⁻ and (OH)⁻ anions, providing the three-dimensional integrity of the crystal structure. Each F⁻ anion is coordinated by three Y³⁺ cations to form planar (FY₃)⁸⁺ triangles parallel to the (010) plane. The triangles share common edges to form [F₂Y₂]⁴⁺ chains parallel to the a axis. The analysis of second-neighbor coordination of Y sites allowed us to identify the structural topology of kuliokite-(Y) as the only case of the skd network in inorganic compounds, previously known in molecular structures only. The variety of anionic content in the mineral allows us to identify the potential existence of two other mineral species that can tentatively be named ‘fluorokuliokite-(Y)’ and ‘hydroxykuliokite-(Y)’. Full article

Skarn-type iron ore is economically significant, and numerous skarn ore deposits have been identified in the North China Craton. The newly discovered orbicular diorite in this region is distinguished from other analogous rocks due to the accumulation of large magnetite particles, which may shed new light on the genesis of this ore type. The magnetite in different parts of the orbicular structure exhibits distinct compositional differences. For example, magnetite at the edge has a small particle size (200 μm) and is associated with the minerals plagioclase and hornblende, indicating that it crystallized from normal diorite magma. By contrast, magnetite in the core has a relatively large particle size (>1000 μm), is associated with apatite and actinolite, and contains apatite inclusions as well as numerous pores. The size of magnetite in the mantle falls between that of the edge and the core. The syngenetic minerals of magnetite in the mantle include epidote and plagioclase. The magnetites in the cores of orbicules have a higher content of Ti, Al, Ni, Cr, Sc, Zn, Co, Ga, and Nb than those in the rim. The δ⁵⁶Fe value of the core magnetite (0.46‰–0.78‰) is much higher than that of the mantle and rim magnetite in orbicules. Moreover, the δ⁵⁶Fe value of magnetite increases as the V content of magnetite gradually decreases. This large iron isotope fractionation is likely driven by liquid immiscibility that forms iron-rich melts under high oxygen fugacity. The reaction between magma and carbonate xenoliths (Ca, Mg)CO₃ during magma migration generates abundant CO₂, which significantly increases the oxygen fugacity of the magmatic system. Under the action of CO₂ and other volatile components, liquid immiscibility occurs in the magma chamber, and Fe-rich oxide melts are formed by the melting of carbonate xenoliths. Iron oxides (Fe₃O₄/Fe₂O₃₎ will crystallize close to the liquidus due to high oxygen fugacity. These characteristics of magnetite in the Tanling orbicular diorite (Wuan, China) indicate that diorite magma reacts with carbonate xenoliths to form “Fe-rich melts”, and skarn iron deposits are probably formed by the reaction of intermediate-basic magma with carbonate rocks that generate such “Fe-rich melts”. A possible reaction is as follows: diorite magma + carbonate → (magnetite-actinolite-apatite) + garnet + epidote + feldspar + hornblende + CO₂↑. Full article

The effects of the La₂O₃/Al₂O₃ mass ratio (L/A-ratio) in electroslag on La yield and the cleanliness of La-containing H13 steel, as well as slag properties were investigated. The slag–steel interaction experiments between slags bearing varying L/A-ratios based on 50wt%CaF₂-20wt%CaO-Al₂O₃-La₂O₃ slag and La-containing H13 steel were conducted. The molecular dynamics (MD) simulation was used to estimate the viscosity, electrical conductivity, and structure of the slag. The results show that La yield increases from 5.3% to 63.2% with L/A-ratio increasing from 0.2 to 5.0 due to the increasing La₂O₃ activity and decreasing Al₂O₃ activity of slag. Thermodynamic analysis indicates that La₂O₃ content should be higher than 23.9 wt% to ensure desirable La treatment effect. The desulfurization and deoxidation ability of slag are enhanced with increasing L/A-ratio. In addition, the phosphorus and arsenic content in steel decrease when the L/A-ratio reaches 5.0, and the removal rates are 20.0% and 33.3%, respectively. This is attributed to the formation of La-O-As-S-P inclusions. The MD simulation results indicate that the increasing L/A-ratio leads to a decrease in viscosity and increase in electrical conductivity. The mechanism is that the increasing concentration of free oxygen simplifies the aluminate network and increases the mobility of ions in slag. Full article

In this study, we present the chemical characterization of red pigment samples and their associated sediments that were collected from three human burial sites in Northeastern Patagonia. Regarding their chronology, the La Azucena 1 site (880 ¹⁴C years BP) corresponds to the period prior to European contact while the Loma Torta and Rawson sites date to periods following contact. These burials were discovered fortuitously. In the case of the La Azucena 1 site it was due to the impact of environmental conditions typical of this region, such as sparse vegetation and the effects of rain and wind, while for the Rawson and Loma Torta sites the burials suffered severe anthropic impact. Analysis of the red pigments and their sediments by a combination of analytical techniques using XRF, XRD, and ATR-FTIR revealed hematite as the chromophore responsible for the red color, together with large amounts of quartz in all the samples. The diffractogram of the red pigment from the La Azucena I site showed notable differences compared to those from the Loma Torta and Rawson sites, with calcite (CaCO₃) and anorthite (Na_0.45Ca_0.56)(Al_1.55Si_21.5O₈) as accompanying minerals and the presence of cristobalite, a high-temperature polymorph of silica (SiO₂), which were not identified in the sediment sample. This suggests that minerals identified in this sample are characteristic of the pigment material rather than of the sediment where the bone remains were found. Full article

According to the production process requirements of oriented silicon steel in a certain steel mill, optimization of the slag composition ratio is studied through thermodynamic calculations. The CaO-SiO₂-Al₂O₃-FeO-MgO slag system is studied using FactSage thermodynamic software (FactSage 8.1), and a slag optimization plan is proposed based on industrial experiments involving changes in the composition ratio of the slag, calculation and analysis of the melting characteristics of RH refining slag, further verification through orthogonal experiments, and observations of the slag state, temperature, and composition relationship through phase diagrams. This study provides theoretical guidance for finding a suitable slag composition ratio based on the influence of slag on dissolved aluminum in steel liquid. Research has shown that, combined with thermodynamic analysis, slag melting characteristics, component content calculations, and industrial experiments, the range of RH refining slag composition suitable for production in this steel mill is slag in the range of 1.3~1.5 alkalinity, 25~30% Al₂O₃, 5~6% MgO, and 1–2% FeO. Full article

The potential for creating composite cements by incorporating fly ash is demonstrated. Analysis revealed that the fly ash examined consists of 69.66 wt. % silicon oxide, 21.34 wt. % aluminum oxide, 1.57 wt. % calcium oxide and 2.78 wt. % iron oxide. Fly ash mainly consists of quartz (SiO₂), goethite (FeO(OH)) and mullite (3Al₂O₃·2SiO₂). The properties of the cement composition containing 5 to 25 wt. % fly ash were studied. Incorporating fly ash enhances system dispersion, promotes mixture uniformity, and stimulates the pozzolanic reaction. Compositions of composite cements consisting of 90% CEM I 42.5 and 10% fly ash were developed. The cement stone based on the obtained composite cement had a compacted structure with a density of 2.160 g/cm³, which is 9.4% higher than the control sample. It is shown that when composite cement containing 10% fly ash interacts with water, hydration reactions of cement minerals (C₃S, C₂S, C₃A and C₄AF) begin first. This is accompanied by the formation of hydrate neoplasms, such as calcium hydroxide (Ca(OH)₂) and calcium hydrosilicates (C-S-H). Fly ash particles containing amorphous silica progressively participate in a pozzolanic reaction with Ca(OH)₂, leading to the formation of additional calcium hydrosilicates phases. This process enhances structural densification and reduces the porosity of the cement matrix. After 28 days of curing, the compressive strength of the resulting composite cements ranged from 42.1 to 54.2 MPa, aligning with the strength classes 32.5 and 42.5 as specified by GOST 31108-2020. Full article

This study investigates the mechanism behind the heat-induced color change (brown to yellowish green) in Mn- and Fe-rich elbaite tourmaline under reducing atmosphere at 500 °C. A combination of analytical techniques including gemological characterization, electron microprobe analysis (EMPA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and ultraviolet–visible (UV-Vis) spectroscopy was employed. Chemical analysis confirmed the samples as intermediate members of the elbaite–fluorelbaite series, with an average formula of ^X(Na₀.₆₆ □₀.₂₆ Ca₀.₀₈) _Σ1.₀₀^Y(Li₁.₂₉Al₁.₁₀Mn₀.₃₁ Fe²⁺₀.₁₅Ti₀.₀₁Zn₀.₀₁) _Σ2.₈₇ ^ZAl₆^T[Si₆O₁₈] (BO₃)₃^V(OH)₃.₀₀^W(OH₀.₅₁F₀.₄₉) _Σ1.₀₀, enriched in Mn (17,346–20,669 μg/g) and Fe (8396–10,750 μg/g). Heat treatment enhanced transparency and induced strong pleochroism (yellowish green parallel c-axis, brown perpendicular c-axis). UV-Vis spectroscopy identified the brown color origin in the parallel c-axis direction: absorption bands at 730 nm (Fe²⁺ d–d transition, ⁵T_2g → ⁵E_g), 540 nm (Fe²⁺→Fe³⁺ intervalence charge transfer, IVCT), and 415 nm (Fe²⁺→Ti⁴⁺ IVCT + possible Mn²⁺ contribution). Post-treatment, the 540 nm band vanished, creating a green transmission window and causing the color shift parallel the c-axis. The spectra perpendicular to the c-axis remained largely unchanged. The disappearance of the 540 nm band, attributed to the reduction of Fe³⁺ to Fe²⁺ eliminating the Fe²⁺–Fe³⁺ pair interaction required for IVCT, is the primary color change mechanism. The parallel c-axis section of the samples shows brown and yellow-green dichroism after heat treatment. A decrease in the IR intensity at 4170 cm⁻¹ indicates a reduced Fe³⁺ concentration. The weakening or disappearance of the 4721 cm⁻¹ absorption band of the infrared spectrum and the near-infrared 976 nm absorption band of the ultraviolet–visible spectrum provides diagnostic indicators for identifying heat treatment in similar brown elbaite–fluorelbaite. Full article

Myanmar blue jadeite jade is a rare and highly prized gemstone, yet its coloration and formative mechanisms remain poorly understood. In this study, petrographic analysis, ultraviolet–visible (UV–Vis) spectroscopy, electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were performed on a sample of Myanmar blue jadeite with small white blocks to investigate its mineral composition, trace element distribution, and coloration mechanisms. Most of the sample was found to be blue, with surrounding white areas occurring in small ball-shaped blocks. The main mineral component in both the blue and white domains was jadeite. Although both areas underwent recrystallization, their textures differed significantly. The blue areas retained primary structural features within a medium- to fine-grained texture, reflecting relatively weaker recrystallization. The white areas, however, were recrystallized into a micro-grained texture, reflecting relatively stronger recrystallization, with the superimposed effects of external stress producing a fragmented appearance. The blue jadeite had relatively higher contents of Ti, Fe, Ca, and Mg, while the white jadeite contained compositions close to those of near-end-member jadeite. It was noted that, while white jadeite may have a high Ti content, its Fe content is low. UV–Vis spectra showed a broad absorption band at 610 nm associated with Fe²⁺-Ti⁴⁺ charge transfer and a gradually increasing absorption band starting at 480 nm related to V⁴⁺. Combining the chemical composition and the characteristics of the UV–Vis spectra, we infer that the blue coloration of jadeite is attributed to Fe²⁺-Ti⁴⁺ charge transfer; i.e., the presence of both Ti and Fe in blue jadeite plays a key role in its color formation. V⁴⁺ exhibited no significant linear correlation with the development of blue coloration. Prominent oscillatory zoning was observed in the jadeite, transitioning from NaAlSi₂O₆-dominant cores to Ca-Mg-Fe-Ti-enriched rims, reflecting the trend of fluid evolution during blue jadeite crystallization. Petrographic analysis indicated that the formation of the Myanmar blue jadeite occurred in two or three stages, with the blue regions forming earlier than the white regions. The blue jadeite also underwent significant recrystallization. Our findings contribute to the understanding of the formation of blue jadeite and the diversity of colors in jadeite jade. Full article