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Objective The aim of this study is to characterize the deep electrical structure of the Baishawo pegmatite-type deposits, explore the spatial distribution of rare metal mineralization models and ore-conferring carriers, and elucidate the relationship between the location of ore veins to provide a basis for prediction in rare metal mineral exploration. Methods Through the controlled-source audio-geomagnetic method (CSAMT) and the conjugate gradient method of inverse measurement of three exploration profiles, deep hidden rock (ore) bodies were detected. Then, by combining these results with the information from drill holes and elemental geochemical anomalies, a comprehensive analysis was carried out to reveal the distribution of the hidden dikes and the mineralization characteristics. Results The study showed that the concealed pegmatite veins are mainly located in the Lengjiaxi Group, where they are concentrated on the top of the granite body and around tectonic fissures and have burial depths ranging from 50 to 300 m. The geophysical signature of pegmatite vein mineralization is a high-resistance vein-like geologic body intruded from a deep high-resistance body into a shallow low-resistance body. Conclusion The determined distribution and burial depth of concealed pegmatite veins, identified potential concealed veins in the study area, and geophysical characteristics of the pegmatite vein mineralization provide a basis for understanding the formation mechanism of fracture zone-constrained pegmatite veins. Significance The research results provide a scientific basis for follow-up exploration of the Baishawo deposit, reveal the formation mechanism of the pegmatite veins, and provide reliable physical exploration and prediction technology and experience useful for rare metal exploration in northeast Hunan and south China.

Kaolin (mainly composed of kaolinite, whose chemical formula is Al2Si2O5(OH)4), serves as a versatile raw material widely used in various industries including production of ceramics, paper, paints, cosmetics, pneumatics, building materials, and hazardous waste storage. In the northern part of Vietnam, due to favorable geological conditions, there are diverse deposits of high quality kaolin of different origin and scale. Decades of research indicate the diversity of kaolin sources in the region, with special attention paid to hydrothermally altered and exchange types of kaolin, the formation of which is associated with complex processes of weathering, hydrothermal alteration and reprecipitation. The aim of this study was to characterize three different types of kaolin derived from different sources in Northern Vietnam (from weathered pegmatites, weathered felsic effusives, and hydrothermal-metasomatic altered rocks). The main focus was to analyze the thermal behavior of these samples during calcination in the temperature range from 300 °C to 1,100 °C. The comprehensive characterization was performed by X-ray diffraction (XRD), FT-IR spectroscopy (FT-IR), thermal analysis (thermogravimetry / differential thermogravimetry (TG / DTG)) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that kaolinite with particle size less than 2 μm was identified in all samples. Minor amounts of muscovite and montmorillonite are present in some samples, and pyrophyllite is present in a sample from the hydrothermally altered rocks. Kaolinite morphology in all the samples showed typical forms including hexagonal and pseudohexagonal. The main chemical constituents of the samples are SiO2 and Al2O3; in addition to these, K2O + Na2O, TiO2 and iron are present in smaller quantities. Thermal analysis allowed to reveal the formation of metakaolinite phase at temperatures around 494 °C and 507 °C in the two studied samples from weathered rocks, while the pyrophyllite-bearing sample undergoes this transition at a higher temperature of 653.8 °C. The onset of metakaolinization was observed at about 500 °C for the weathered rock samples and about 700 °C for the pyrophyllite-bearing sample. In addition, mullitization leading to the formation of mullite was evident at 1,100 °C. The study findings allow concluding that the studied kaolins can be used in traditional ceramics production.

Abstract In the county of Pedra Lavrada - PB, various mineral occurrences of pegmatite are observed with prominence at Alto Dois Irmãos - PB, where quartz, feldspar and mica are mined. The understanding of mineral constituents is fundamental to define their industrial employment and to implement improvements in the beneficiation process. The proposal of this research is the detailed characterization and proof of that part of the ore (quartz) considered waste, presenting low poisoning (Fe2O3) and high silica (SiO2) content, to enable its industrial use. Besides that, to minimize the environmental impact through the reuse of this waste, and to determine the correct utilization of the milling equipment. For the pegmatite characterization, done were density determination tests, mineralogical identification by X-ray diffraction (XRD), chemical analysis by fluorescents X-rays and morphological analysis by scanning electron microscopy (SEM/EDS). Then tests were done for the Work Index (WI) calculous and consequently the empirical determination of the dimensions (LxD) of the pebble mill. The sterile presented a medium density of 2.66g/cm³, majority chemical composition of silicon and oxygen and quartz as the main mineralogical stage, indicating that this material has high purity. The. The Work Index (WI) was 15.9 kwh/t showing that this material can be considered resistant to breaking in the grinding process. The necessary energy to the milling was defined in 11.52 kwh/st, that corresponds to 57.28 HP. This power allowed the mill selection with diammeter and length of 1.83m, that provides the production maximization and the energy saving.

The global need for lithium (Li) is increasing due to its use in batteries which are used to make electric vehicles, wind turbines and fuel cells to facilitate the world’s ‘green transition’ to low carbon economies. The mining of Li, like that of other Earth materials, produces large volumes of waste such as tailings and processing chemicals. A growing body of research is addressing the resource potential and environmental impacts of wastes from mining of Li-bearing granites and pegmatites that produce around 40% of the world’s Li. The wastes are dominated by SiO2 and Al2O3, with lesser Na2O, K2O and Fe2O3, that are hosted in quartz, feldspar and micas. They can contain around 1 wt% Li2O that is found in residual spodumene, lepidolite and zinnwaldite, and trace (

Pegmatite (sample 13/10) exposed in the valley of the Berezivka River (Krynychuvatka village) was studied and its isotopic age was determined by monazite. Granitoids of the Krynichuvatsky massif differ from other granitoids of the Kirovohrad complex in their petrographic composition (mainly plagioclase, plagioclase-microcline), structural (aplitoid, pegmatoid inclusions) and texture (in some areas, aplitoid granites are characterized by linearly oriented grains of lamellar (lenticular) quartz, elongated feldspar crystals) and the composition of xenoliths (amphibolites, amphibole-biotite, biotite, pyroxene-biotite gneisses). To find out the time and duration of the formation of granites of the massif using the uranium-lead isotope method, we determined the age of the monazite of the apilito-pegmatoid granite (sample 12/10) — 2039.9±1.4 Ma. The age of the vein body of the pegmatite (sample 13/10) has now been determined that is widespread above the dam on the right side of the stream, the left tributary of the Berezivka River, village Krynychuvatka. Monazite occurs mainly as large (> 0.1 mm) diskshaped crystals with well-developed pinacoid facets and, in individual grains, several other facets and even ribs. The crystals are yellow, honey yellow to honey transparent and translucent. Light-yellow, water-transparent crystals with an even, smooth, shiny surface and rounded contours are present singly. Considering the fact that the main mass of granites (aplito-pegmatoid granites) exposed in the valley of the Berezivka River (Krynychuvatka village) are 2039.9±1.4 Ma, and the vein body of peg9 matite that dissects the granite was formed in 2029.1± 3.4 Ma, it can be assumed with a high probability that the Krynichuvatsky massif was formed for at least 10 million years, in the age interval of 2040—2030 Ma ago.

The Barroso–Alvão region is an excellent setting for studying Li mineralization associated with granitic pegmatites and developing Li exploration techniques. Among the distinguished pegmatite types in this pegmatite field, the spodumene-bearing dyke from Alijó is a representative example of an Iberian Li–Cs–Ta (LCT) pegmatite currently under exploitation. In this work, we examine the internal evolution of the Alijó dyke and its external metasomatic effect on the surrounding metasediments, contributing to lithium exploration techniques. Electron microprobe analyses provided clues about the crystallization conditions and the degree of differentiation of the pegmatitic melt, whereas the external metasomatism induced by the spodumene-bearing pegmatite was studied through whole-rock geochemistry. The obtained results indicate that the primary crystallization of the studied dyke likely occurred at temperatures between 450–500 °C, with emplacement at shallow crustal levels of about 2–3 kbar. The high concentrations of trace elements such as Li, Cs, Rb, Be, Sn, Nb, Ta, Ge, U, and Tl in the pegmatitic melt suggests high availability of these elements, allowing their partitioning into an early exsolved fluid phase. The exsolution of this fluid phase, subtracting components such as F and B, from the pegmatitic melt would cause a significant undercooling of the melt. Moreover, the interaction of this expelled fluid with the country rock generated a metasomatic overprint in the surrounding metasedimentary host rocks. The metasomatic effect in Alijó is strongly influenced by the nature of the host metasediments, with a significantly higher grade of metasomatism observed in pelitic (mica-rich) samples compared to psammitic (mica-poor) samples collected at same distances from the dyke. The greisen developed close to the pegmatite contact reflects this metasomatic signature, characterized by the mobilization of at least B, F, Li, Rb, Cs, Sn, Be, Nb, Ta, and Tl. We cautiously suggest that whole rock Li concentrations greater than 300 ppm, combined with a minimum value of 1000 ppm for the sum of B, F, Li, Rb, Cs, and Sn in pelitic metasediments of Barroso–Alvão, may be indicative of a mineralized pegmatite in this region.

A modified model based on classical nucleation theory was applied to a natural hydrous peraluminous pegmatite composition and tested against crystallization experiments in order to further investigate the quantification of nucleation delay in felsic melts. Crystallization experiments were performed in a piston-cylinder apparatus at 630 MPa and temperatures between 650 and 1000 °C for durations ranging from 0.3 to 211 h. Experimental run products were investigated by scanning electron microscopy paired with energy dispersive spectroscopy analyses of both crystalline and quenched liquid phases, the results of which were compared to an established theoretical nucleation delay model from the literature. The experiments showed good agreement (within a factor of 5) with the model for quartz, while it showed moderate agreement (within a factor of 10) with the model for sodic feldspar. Other crystals also nucleated, demonstrating abundant features of disequilibrium. Our research further demonstrates the potential of the model to predict nucleation delay, showing promising results for the quantification of the nucleation delay of quartz and feldspar in natural felsic melts, thus adding to previously published studies on hydrous, metaluminous, felsic melts and dry basaltic melts.

Blue-colored corundum (sapphire) is found in syenitic pegmatites in Alvand igneous complex in the Khako area. From the petrographic point of view, the host rock is composed of feldspar and small amounts of quartz, which includes corundum crystals of transparent to translucent blue color, 1 to 6 cm long, covered with a sheath of mica with a composition of muscovite to phengite. It seems that the core of corundum crystals crystallized in the magmatic stage in equilibrium with mica + aluminosilicate + feldspar ± perthite, and in the next metasomatic stage, corundum crystals grew from the reaction of plagioclase and mica. The chemical composition of the main minerals in pegmatite rocks indicates the magmatic origin of these rocks, which were formed during the magmatic differentiation process. In the continuation of the metasomatic cycle, the geochemical conditions for formation of new corundum crystals and regrowth of primary corundum have been prepared by reducing the silica content (de-silicification) and increasing the Al/Si ratio. These processes during post-magmatic cycles in granite masses, are known as Plumasite processes. The classifications done in pegmatites, based on abundance of rare elements and phosphorus content in feldspar crystals, indicate fertility of these rocks from rare elements. These pegmatites are included in the group rich in lithium and beryllium. Moreover, comparison of the chemical composition of corundum crystals with famous corundum deposits in other parts of the world shows that these rocks have a special similarity with magmatic corundum deposits in connection with synthetic intrusive masses. In addition, these rocks show a composition similar to magmatic deposits created by metasomatic processes. Introduction The corundum crystals found in the southern part of Alvand's intrusive mass have been introduced as the most important sapphire gem potential in Iran (Sadeghi et al., 2022; Sajjadi Alehashem et al., 2021). The corundum crystals in this area have been reported in preliminary studies conducted by different researchers (Beharifar, 2012). Although it is not possible to determine certain criteria for the gem value of a mineral., characteristics such as transparency, color, hardness, refractive index, reflection, and absorption of light are among the most important factors in determining the quality of colored gems. The crystallized oxide of pure corundum is colorless However, corundum has five main coloring elements, including Cr3+, Fe3+, Fe2+, Ti4+ and V3+. Geochemical factors in the formation of corundum are usually magmatic or high-grade metamorphic processes that cause formation of aluminum oxide crystals from a magma with a low silica content (Černý, 1991; Černý and Ercit, 2005) or a differentiated pegmatite magma (Sánchez-Muñoz et al., 2017). These rocks can provide special conditions to produce corundum with the help of fluids originating from magmatic fractionation and metamorphic processes (Zwaan et al., 2015; Peucat et al., 2007). Many studies have been done on classification and genesis of corundum deposits (Sutherland et al., 2009, Schmetzer and Peretti, 1999; Simonet et al., 2004). Classification of corundum reserves is essential in choosing detailed prospecting and exploration methods and prospecting for new reserves in similar structural zones. Materials and methods 25 thin sections were prepared from the collected samples. 5 thin polished sections have been used in electron microscope studies and electron probe microanalysis (EPMA). 5 samples of pegmatites containing corundum crystals found in the Khaku deposit Index and 10 single crystals of separated corundum crystals, have been chemically analyzed by XRF and ICP-MS methods in Zarazma Company of Tehran under standard conditions for major elements and trace elements. Also, EPMA analysis of accompanying minerals and corundum crystals was performed by a Cameca-SX-100 device with a beam diameter of 5 microns and accelerating voltage of 2400 mA at the Iranian Mineral Materials Processing Research Center in Karaj. Results In the newest pegmatite classification (Černý, 1991; Černý and Ercit, 2005), which is most widely used by researchers nowadays, a combination of factors, including depth of establishment, metamorphic degree, and rare element contents are considered. This classification has 4 main categories or classes including 2 Abyssal classes (high grade, high pressure to low), Muscovite (high pressure, low temperature), and Miarolitic (shallow level of rare element with low temperature and pressure). The class of pegmatites with rare elements is divided into LCT and NYF types based on abundance of rare elements: LCT Type is rich in lithium, cesium, and NYF type tantalum and rich in niobium, yttrium, and fluorine. Descriptions of sub-groups by Pezzotta Corundum-bearing pegmatites are included in the Abyssal sub-group. This group is of high pressure and temperature type and is formed at a temperature between 700 and 800 degrees Celsius and a pressure of 4 to 6 kbar (Černý and Ercit, 2005). The mineral abundance of muscovite and biotite shows that Alvand pegmatite shows few characteristics of the muscovite subgroup (high pressure, low temperature). This indicates formation of these rocks at temperatures lower than 700 degrees Celsius. A mineralogical classification is based on the latest classification done in pegmatites (Müller et al., 2022). The pegmatites of the Khaku area are in the corundum pegmatites, a product of magmatism, and are affected by the processes of subsolidus fluids. This group of pegmatites are mostly rich in rare elements and aluminum. Chlorite is the most abundant secondary mineral in corundum-bearing rocks. The chemical composition shows that chlorites of the region are rich in iron and poor in titanium and calcium, their XMg varies from 0.23 to 0.37 (Table 3), and in the classification of chlorites, they are in the range of pycnochlorite to diabenitite (Fig 4-A). The 8 samples of biotite and muscovite from the Khaku region were analyzed by EPMA (Tab 4). There were four biotite crystals in sample SH-1, and four other muscovite crystals in sample SH-3. The structural formula of micas has been calculated based on 11 oxygen atoms and 8 cations (Deer et al., 2013). The lowest amount of XMg in sample SH-1 is equal to 0.46, and the highest amount of XMg in sample SH-3 is equal to 0.56. According to Al versus Fe/Fe+Mg variations (Deer et al., 2013). These biotites are a compositional variety between polar siderophyllite and anite (Fig 3-B). The chemical composition of feldspars in the Khaku region shows a relatively uniform chemical composition rich in albite and a major part that is rich in an orthosis in pegmatites such that XAb is equal to 0.90 to 0.95. Most of the feldspars have a composition of orthosis type XOr 85 % to 90% (Tab 5). In the ternary diagram of albite-anorthite-orthoses (Deer et al., 2013), feldspars in pegmatites are located in the orthosis zone and in the zone of pure albite and oligoclase (Fig 3-C). The results obtained from chemical analysis of corundum crystals show that they all contain 86% to 97% aluminum oxide (Al2O3). In all the samples analyzed by theSiO2 method as the second main oxide, there is more than one percent in the crystal., and it varies in the range 1.01%-1.46% to. Discussion The geochemical and geotectonic characteristics of pegmatites in the Khaku area are like those of group II and III pegmatites of the classification of Sánchez-Muñoz et al., (2017), indicating that they are the result of primary crystallization from magmatic melts After those subsolidus reactions during exhumation and cooling rock mass has caused crystallization of corundum and condensation of rare elements (Fig 5). The samples of Khaku are in the range of corundums of magmatic origin and along the dividing line of the magmatic and metamorphic region. These crystals have significant similarities with blue sapphires from the Bo Phloi mine in Thailand (Bo Phloi/Thailand), which are magmatic-metasomatic corundums rich in titanium and magnesium (Fig 6-A). Chromium is also an important tracer in corundum with metamorphic genesis, especially corundum crystallized in alumina-rich marbles and under severe metasomatism. From this point of view, the corundums of the Hamedan Khaku deposit have relatively low amounts of chromium and vanadium and are among the metasomatic magmatic deposits. They are comparable to the sapphires of the Mogok mine in Myanmar (Mogok/Myanmar) (Fig 6-B). This mine is of the metamorphic magmatic type containing ruby in alumina-rich marbles with intense metasomatism (Peucat et al., 2007).

The Ke'eryin area in Sichuan province is one of the large rare metal ore concentration areas in the Songpan–Garze metallogenic belt. Numerous granite pegmatite dikes spread around the Ke'eryin mass. However, locating rare metal dikes in such a large pegmatite field has always been one of the challenges in this region. This paper summarized the geochemical element distribution in the Ke'eryin pegmatite and put forward geochemical indexes, e.g., characteristic element indexes, indicator indexes and grade indexes, to locate rare metal ore in the Ke'eryin area based on a systematic petrogeochemical analysis of two-mica granite, pegmatite microcline albite granite, different pegmatite types and typical deposits. Characteristic element indexes include Li, B, Sn, Rb, Be, Nb and Ta, etc. Indicator indexes for lateral variation are Cs, Tl, F, Zr, Y and ΣREE elements as well as values, e.g., TiO2/Ta, Zr/Hf, Ta/Zr, Nb/Ta, K/Na, etc., while indicator indexes for vertical variation include B, U, Zr, Be, Sn, Rb, Sr, Ba, Tl and In, etc. The variation in these indexes can be used to locate rare-metal-mineralized pegmatite, indicating ore bodies in a deep basin. Grade indexes are aluminum saturation index（A/CNK, A/NK）and rittmann index(σ), etc. Li ore grade is positively correlated with aluminum saturation but is negatively correlated with alkalinity. Grade index variation is a good indicator of lithium enrichment in ore bodies.

Lithium (Li) can be found in many minerals, including lepidolite. Lepidolite is found in pegmatite-related tin deposits in the Phang Nga area in southern Thailand. According to their field occurrence, petrography, mineral chemistry, and whole-rock geochemistry, the Li-bearing pegmatites and the granitic rocks in the study area can be linked to tin deposits in southern Thailand as part of the SE Asian tin belt. The Li-bearing pegmatites are characterized by an abundance of lepidolite, K-feldspar, plagioclase, and quartz with some accessory minerals of fluorite, cassiterite, apatite, monazite, and beryl. The granitic rocks show various compositions, including porphyritic biotite–muscovite granite, biotite granite, and muscovite—tourmaline granite with different proportions of K-feldspar, plagioclase, quartz, biotite, muscovite, and tourmaline. Whole-rock geochemistry indicates that both the Li-bearing pegmatites and granitic rocks have a close relationship rooted in their peraluminous S-type granite affinity. The Li-bearing pegmatites evolved from highly fractionated S-type granitic rocks comparable with the Western Belt Granite of Thailand. The enrichment of large-ion lithophile elements (e.g., Rb and K) and the depletion of Ba, Nb, and Ti together with similar rare Earth element patterns reflect the collisional setting indicating the Sibumasu–West Burma and West Burma—Indo-Burma collisions during the Cretaceous to the Eocene. The crystallization pressure—temperature conditions of these rocks were 3.49–4.25 kbar and 622°C–675°C, respectively, with an emplacement depth of 13–15 km. The Li-bearing pegmatites had a relatively high average Li grade compared with those of other Li-bearing pegmatites in the world.

In this paper we present textural and compositional data for columbite group minerals (CGMs) and associated Nb-Ta-Sn oxides from lithium-beryllium-tantalum pegmatite deposits of the Kolmozero–Voronja belt, NW Russia, with the aim of deciphering these characteristics for minerals from deposits with different mineral signatures and lithium ore grade. Minerals from four deposits, including two of world-class (Kolmozero and Polmostundra), are examined. The main controlling factors for CGM compositional ranges are the diversity and rate of magmatic fractionation, hydrothermal overprint and mineral paragenesis, following the specific geochemical signature of the different pegmatite deposits. CGM from Kolmozero include several mineral species (columbite-(Fe), columbite-(Mn), tantalite-(Fe), and tantalite-(Mn)), showing large compositional variations, mainly controlled by Nb-Ta fractionation (Ta/(Ta + Nb) = 0.16–0.70; Mn/(Mn + Fe) = 0.45–0.63). Textural patterns are various (oscillatory, homogeneous, and patchy); spongy domains and overgrowing Ta-rich rims are also observed somewhere. This indicates the involvement of numerous magmatic and hydrothermal processes. The Polmostundra CGMs are represented by columbite-(Fe) with Ta/(Ta + Nb), ranging from 0.05 to 0.39; some crystals are homogenous, and others present normal, oscillatory, mottled and reverse-zoning patterns. The Okhmylk CGMs are irregular normal, patchy and homogeneous columbite-(Fe) and columbite-(Mn), with Ta/(Ta + Nb) = 0.09–0.24 and Mn/(Mn + Fe) = 0.29–0.92, indicating the suppressed magmatic fractionation and iron drop due to precipitation of Fe minerals. Columbite-(Fe) and columbite-(Mn) from the Be-Ta Shongui deposit are less evolved, with Ta/(Ta + Nb) = 0.07–0.23 and Mn/(Mn + Fe) = 0.31–0.55. The minerals are characterized by progressive normal, oscillatory, homogeneous and irregular reverse patterns. Associated pyrochlore minerals occur both as early magmatic (Kolmozero) and late hydrothermal (Polmostundra, Okhmylk). Cassiterite is found only in the Okhmylk dykes, and is apparently of hydrothermal origin. CGM from Li pegmatites have impurities of Ti (0.01–0.05 apfu) and W (up to 0.02 apfu), whereas CGM from Be pegmatites contains elevated Ti (up to 0.09 apfu). The mineral system analysis presented here is relevant for exploration.

Prydz Bay is an important part of the Pan-African high-grade tectonic mobile belt. The focus of this investigation, by applying zircon LA-ICP-MS U-Pb geochronology, zircon Lu-Hf isotope systematics, and whole-rock geochemistry, is on Pan-African pegmatites in the Larsemann Hills of Prydz Bay, East Antarctica, their association with country rocks, and the formation conditions. Based on the obtained results, it is concluded that the pegmatites exhibit elevated levels of silica and alkali and possess peraluminous features. These pegmatites originated during the late Neoproterozoic–Early Cambrian (Pan-African) event, specifically in the D2–D4 stages. The D2 stage occurred between 546 and 562 Ma, followed by D3-stage pegmatites around 534 Ma. The pegmatites from the D2–D3 stages are considered to originate from Paleoproterozoic crustal materials, while there are at least two phases of pegmatites in the D4 stage (~517 Ma and ~521 Ma). The D4-1 pegmatite (~521 Ma) suggested both Paleo–Mesoproterozoic crustal origin, perhaps connected to extension. The D4-2 pegmatite (~517 Ma) originated from the crust layers. In the Larsemann Hills, Pan-African pegmatites formed in a recurring regime of tension. Therefore, the obtained data elucidate that a Pan-African stretching process might have occurred in Prydz Bay.

The pegmatite in the Dagbala area, southwestern Nigeria occurs as a dyke trending in a NW-SE direction which intrudes the Hornblende-Biotite-Granite. Geochemical, petrological, and mineralogical analyses were carried out on four (4) pegmatite samples obtained from the study area to determine the feldspar quality and the results were compared with commercial ceramic and glass grade to determine its suitability in ceramics and glass production. From the results, SiO2 ranges from 74.97% to 72.06%, Al2O3 ranges from 15.16% to 15.05%, Fe2O3 ranges from 0.45% to 0.31%, Na2O ranges from 5.56% to 2.76%, K2O ranges from 8.42% to 3.53% and CaO ranges from 0.72% to 0.09% respectively. After comparing the results with the commercial ceramic grade and glass grade, it shows that they can be used as raw materials in the ceramic and glass industry. However, minor pre-treatment processes are required, such as magnetic separation, to reduce the Fe2O3 content and froth floatation to reduce the K2O content in ceramic production. In glass production, magnetic separation should also be carried out to reduce the Fe2O3 content and froth floatation should be carried out to reduce the K2O content. Additives should be added to increase the amount of CaO, Al2O3, and Na2O present.

Pegmatites occur in association with amphibolites, minor granite-gneiss and quartzites in central Nigeria. Findings on their economic potentials are yet to reveal more representative and accurate depiction of their characteristics. This paper employs both geochemical and mineralogical evaluation for ample economic potentials based on computation of analyses of low-lying dome shaped hills of granitic rocks that intruded the undifferentiated basement. Thirty (30) representative muscovite extracts from the pegmatite samples were analysed for major-trace and rare earth elements using Inductively Coupled Atomic Emission Spectrornetry (ICP-AES).The chemical data shows that the rocks are siliceous with high SiO2 content(65.30 - 84.93%). CaO (0.11-0.35), MgO (0.17-0.41), and TiO, (0.0-0.85) values are generally low. Averages for Na2O and K2O are 2.87% and 1.87% respectively. The rocks are low in alkalis, indicating low to moderately high albitization, progressive rare alkali fractionation, and controlled Ta-Nb enrichment. Trace elements revealed Rb (1123.93 ppm), Ta (2016ppm), Be (88.6ppm), Ba (674.87ppm) and Nb (5150.8ppm).Elemental ratio for Rb/Sr (0.0066) and Mg/Li (0.00034) is low in certain.The enrichment variation plots of K/Rb versus Rb,Ta versus Rb, Ta against Nb, and Ta against Cs also revealed that have moderate to high Ta-Nb mineralization. Qualitative characterization of mineral phases is quartz, feldspar, biotite, mica,silica...

A suite of highly fractionated granites and associated pegmatite, were revealed through drill hole in the Anqing ore-cluster region in the Lower Yangtze River Belt (MLRB), Eastern China, for the first time. The pegmatite has abundant tourmaline. This discovery provides new clues for the prospection of boron and rare metals in this region.

Most recent studies consider the formation of individual pegmatite bodies to be a fast process with estimated crystal growth rates reaching a walloping 10 m/day. This opinion is presumably underpinned by the traditional way of thinking of them as the end products of magmatic fractionation. Indeed, modelling has shown that if a pegmatite-forming substance with a temperature near granitic solidus intrudes into a much colder host rock, as recorded in some outcrops, it must cool rapidly. From here, a conclusion is made that the crystallisation must likewise be rapid. However, this view is challenged by several studies that published isotopic dates supported by petrological characterisation of the analysed materials, which suggested or can be used to suggest that some minerals in pegmatites grew over millions of years. Surprisingly, such in-depth work on the geochronology of individual pegmatite bodies is relatively uncommon, so it is early to make generalisations. Here, I highlight some of the existing evidence with the aim to stimulate further research into the timescales of pegmatite crystallisation, including the use of petrologically constrained isotopic dating.

Leucogranitic rocks, mainly including leucogranite-pegmatite systems, have been found to be widely distributed in the South Tibetan Himalaya, and they have received considerable interest because of their significance in crustal evolution and associated rare-metal mineralization. Although the nature and geodynamic setting of the Himalayan leucogranites have been well documented by numerous studies, the pegmatites spatially associated with these leucogranites are still poorly understood. Tourmaline is a ubiquitous phase from the leucogranite to the pegmatite. We have therefore conducted in situ major and trace element and boron isotope investigations of tourmaline from the Gyirong pegmatite, synthesizing published data on the Gyirong leucogranite, to document the origin of tourmaline and its genetic implications. Two types of tourmaline (Tur-Ⅰ & Tur-Ⅱ) have been identified in this contribution and they are enriched in Fe, Si and Al but depleted in Mg and Ca, with Mg/(Mg+Fe) ratios ranging from 0.22 to 0.45. Accordingly, the tourmalines belong to the alkali group and have schorl composition. Trace elements, such as Zn, Ga, V, Sc, Li, Sn, Sr, and Co in the tourmalines are relatively enriched, whereas, other trace elements record low concentrations less than 10 ppm. The trace element concentrations of tourmaline are mainly controlled by melt composition. Morphological and geochemical characteristics reflect that the tourmalines from the Gyirong pegmatite are magmatic in origin. The Gyirong pegmatitic tourmalines have S-type granitoids and pegmatites boron isotopic signatures with a tight range of δ11B values between −11.8 and −9.7‰, which is consistent with the magmatic tourmalines (Mg-poor) of the Gyirong leucogranite. This study suggests that the Gyirong pegmatite was the product of crustal anatexis and that the crustal metapelitic rocks within the Greater Himalayan Crystalline Complex were the most likely source components.

Fluid exsolution in magmas is a process that, in many silicic upper crustal reservoirs, starts at relatively low crystallinities (near liquidus), and precedes the precipitation of many ore bodies, including pegmatites. As any magmatic system approaches its solidus, the amount of the exsolved fluid phase increases and becomes progressively dominant over melt, allowing local over pressurization and the generation of pegmatitic pods/dykes. Such pegmatitic bodies show several features that point to both magmatic and hydrothermal environments, linking those realms and providing a unique opportunity to document and understand the magmatic-hydrothermal transition within silicic magmatic systems. We studied the 1.1 Ga classic A-type Pikes Peak granite (Colorado, United States) and one of its many internally-hosted pegmatites, the Wellington Lake pegmatite, to investigate the changes that occur within a granitic system as it crosses its theoretical water-saturated solidus and continues crystallizing beyond it. Textural and geochemical analyses of quartz, plagioclase, and K-feldspar minerals, as well as fluid inclusion studies, demonstrate this magmatic to hydrothermal transition in the granite and the pegmatite. Different thermometers (Ti-in-quartz, 2-feldspars, fluid inclusions) document the temperature evolution of the granitic system, from >850°C for the hottest magmatic minerals to

Lithium (Li) has grown to be a strategic key metal due to the enormous demand for the development of new energy industries over the world. As one of the most significant sources of Li resources, pegmatite-type Li deposits hold a large share of the mining market. In recent years, several large and super-large spodumene (Spd)-rich pegmatite deposits have been discovered successively in the Hoh-Xil–Songpan-Garzê (HXSG) orogenic belt of the northern Tibetan Plateau, indicative of the great Li prospecting potential of this belt. Hyperspectral remote sensing (HRS), as a rapidly developing exploration technology, is especially sensitive to the identification of alteration minerals, and has made important breakthroughs in porphyry copper deposit exploration. However, due to the small width of the pegmatite dykes and the lack of typical alteration zones, the ability of HRS in the exploration of Li-rich pegmatite deposits remains to be explored. In this study, Li-rich pegmatite anomalies were directly extracted from ZY1-02D hyperspectral imagery in the Zhawulong (ZWL) area of western Sichuan, China, using target detection techniques including Adaptive Cosine Estimator (ACE), Constrained Energy Minimization (CEM), Spectral Angle Mapper (SAM), and SAM with BandMax (SAMBM). Further, the Li-rich anomalies were superimposed with the distribution of pegmatite dykes delineated based on GF-2 high-resolution imagery. Our final results accurately identified the known range of Spd pegmatite dykes and further predicted two new exploration target areas. The approaches used in this study could be easily extended to other potential mineralization areas to discover new rare metal pegmatite deposits on the Tibetan Plateau.

The Huayangchuan uranium deposit, located in the west of the Xiaoqinling belt on the southern margin of the North China Craton, is a large U–Nb–Pb deposit accompanied with rare–earth elements. The Huayangchuan uranium deposit, discovered in the 1950s, has long been known as a carbonatite–type uranium deposit. Recently, new geological work has found uranium mineralization in many granitic pegmatite veins in the Huayangchuan deposit and adjacent areas. Here, we report a systematic investigation of the petrography, whole–rock geochemistry, zircon U–Pb ages, and in situ Lu–Hf isotopic characteristics of newly discovered U–rich granitic pegmatite veins in the west of Huayangchuan deposit. The petrological results showed that the lithology of the samples is granite pegmatite. The U–Pb ages of zircon were 1826.3 ± 7.9 and 1829 ± 11 Ma. Microscopically, the paragenetic characteristics of zircon, betafite, and uraninite exist in the intergranular fissures of K–feldspar and quartz, reflecting metallogenic phenomena in the rock formation process. Almost all whole–rock samples were rich in SiO2 (64.37−70.69 wt.%), total alkalis (K2O + Na2O = 8.50–10.30 wt.%), and Al2O3 (12.20–14.41 wt.%) but poor in TiO2 (0.23–0.73 wt.%), MgO (0.38–0.90 wt.%), CaO (1.23–2.22 wt.%), P2O5 (0.14–0.83 wt.%), and MnO (0.04–0.57 wt.%). Additionally, they showed enrichment of LILEs (such as Rb, Ba, Th, U, and K), depletion of HFSEs (such as Ta, P, Ti, and Hf), and no alkaline dark minerals, and the characteristics are intraplate A1–type granite. The A1–type granite displayed low zircon εHf(t) values (−19.42–−15.02) with zircon two–stage Hf model aged 3.10–2.76 Ga, indicating that the U–rich granitic pegmatite was derived predominantly from partial melting of the ancient continental crust (such as the early Taihua group formed in Archean–Neoarchean). Combined with the above results and regional geological data, the U–rich granitic pegmatite discovered in the Huayangchuan deposit was formed in a post–collisional regime after the Luliang movement in the late Paleoproterozoic. This study suggests that future uranium prospecting work in this area should focus on late Paleoproterozoic U–rich granitic pegmatites.

For a better understanding of the previously observed increased natural radioactivity at the confluence of the Varzob and Sioma rivers, Central Tajikistan, the activity concentration of natural radioactive 40K, Th and U daughters as well as of the anthropogenic 137Cs were determined in nine locations covering the entire Sioma River. The radiometric determinations evidenced, in addition to increased activity concentrations of Th and U daughter radionuclides, an anomalous accumulation of anthropic 137Cs and natural 210Pb in the middle of the Sioma gorge. Complementarily, the mass fractions of natural Th and U determined by instrumental neutron activation analysis evidenced an increased presence of Th and U, which, in some places, overpasses six-times the average mass fraction found in the upper continental crust. The possible influence of active air transport from the southern Tadjik plane during the Afghani storms, as well as the presence of actinide-rich minerals, were analyzed and discussed.

The pegmatite deposit is one of the most important types of rare metal deposits in the world, and it is also one of the most popular interests in the international deposit research.Significant advances have been made in the latest decades, including the classification, source of ore-forming fluids and materials, pegmatite diagenesis mode and enrichment mechanism of rare metals.Ore-related pegmatites have closely temporal-spatial relationship with parental magmatism in general.However, some pegmatites do not show this relative genetic relationship.Studies indicate that the ore-forming melts/fluids of rare-metal pegmatite deposits have properties such as low viscosity, rich water, high dispersibility, and rich alkali, leading to extreme enrichment of elements such as P, F, and B in pegmatite, which migrates and enriches together with rare metals in various complexes or compounds.Li-Cs-Ta type (LCT) pegmatites are closely related to S-type granites.The ore-forming materials are mainly originated from marine sediments like black shale, whereas Nb-Y-F type (NYF) pegmatites are generally associated with A-type granites, which are all derived from the same magmatism.Granitic magma fractional crystallisation and partial melting of crustal or mantle-derived rocks are the two significant formation modes of pegmatites.Meanwhile, three enrichment mechanisms, including fluid immiscibility, highly crystalline differentiation of the flux-rich granite slurry and hydrothermal metasomatism, are widely used to interpret the formation of rare metal pegmatite deposits.

Tashina area, as a part of the Sanandaj- Sirjan magmatic- metamorphic Zone, located 10 kilometers north of Serkan city and on the southern slope of Kuhe- Gavbar. The most important geological unit is the porphyroid granite belonging to the Middle Jurassic. Tourmaline is observed as massive in pegmatites and as quartz tourmaline veins within the host granodiorite. The massive tourmalines are spherical, elliptical, elongated, and radial, and sometimes it is so abundant that it can be as the tourmalinite type. Optically, the massive tourmalines show brown- green in color, sometimes very intense intefrance whereas the tourmaline veins are brown- green and blue (indicolite). Indicolite related to the tourmaline delayed phase and is newer than brown- green tourmalines.The studied tourmalines are Fe- rich and schorl type, base on EPMA data as well as several diagrams. The tourmaline in the quartz- tourmaline veins are the vacancy type while the second type is often alkaline with tendency to this group. Euhedral forms and the lack of chemical zoning, with high Al and Fe/Fe+Mg contents, deficiency in X sites, and plentiful tourmaline in host granitic rock which is Li poor are all indicative of the magmatic origin of tourmaline enriched in B. The presence of Ba, Eu, Nb, and Sr negative anomalies in the studied samples and the separation of plagioclase and K- feldspar can be accounted as important factors in magmatic evolution of the studeid rocks. Overall, the results of petrographic studies are well in accordant with trace and REE geochemistry data.

A net of pegmatite veins crosscut gneiss and dismembered ophiolitic ultramafic rocks are abundant in the Migif-Hafafit culmination area, South Eastern Desert, Egypt. Some of these pegmatites are corundum-bearing. Corundum-bearing pegmatites are studied in eight localities around the Migif-Hafafit complex. The present study aims to integrate field investigation, whole rock and corundum chemistry, remote sensing studies, and the conventional methods to detect the corundum-bearing pegmatites, which led to finding out the genesis of the corundum mineralization. In addition, the tectonic regime has been detected using bulk rock geochemistry. False-color composite (FCCs), band ratio (BR), principal component analysis (PCA), minimum noise fraction (MNF), decorrelation stretch (DS), and the constrained energy minimization (CEM) image processing algorithms were proposed and applied on Landsat-8 OLI, and Sentinel-2A data to discriminate the exposed lithological units and to detect the corundum-bearing pegmatites in the study area. These detected pegmatites are structurally controlled following the NW-SE direction. The ultramafic rocks are the host of six areas and the gneisses are the host rocks of the two others. Gneisses and pegmatites are characterized by a steep slope of LREEs relative to HREEs with week Eu negative anomaly. The studied pegmatites have both plumasite and marundite. On the other hand, the studied corundum has Al2O3 content up to 99.72 wt% in pegmatite-gneiss and up to 100 wt.% in pegmatite-ultramafics. Corundum is ascribed to metamorphic/metasomatic type according to its chromosphere. Desilication in pegmatites led to the excess of alumina content in the residual melt producing corundum mineralization.

Abstract Two porphyritic granitoids (Huaco and Sanagasta) in the Velasco district of the Pampeana Pegmatite Province in Northwestern Argentina are recognized. They are considered the fertile granites of the beryl-bearing pegmatites and can be described as post-orogenic and peraluminous A-type granites formed in an intraplate tectonic setting during an extensive regime, whose magma source is predominantly of cortical origin and to a lesser extent, mantle-derived. The pegmatites are classified as Rare Elements of the beryl type and beryl-columbite-phosphate subtype, while the entire district shows characteristics related to the NYF (Nb-Y-F) petrogenetic family. From rocks and cogenetic minerals of an individual ‘Ismiango’ pegmatite of the Velasco district, two Rb/Sr isochrons have been constructed. They define an age of 330.3 ± 8.3 and 331.7 ± 2.3 Ma and fall in the Lower Carboniferous period, consistent with the age of the parental and host-rock, the Huaco granite. As the Ismiango pegmatite has a similar composition and structure to the other beryl mineralized pegmatites of the Velasco district, the obtained age is attributed extensively for the entire district. According to the initial 87Sr/86Sr value obtained of 0.713, the pegmatite-magmatism of the Velasco District might be mainly derived from the crust with some minor participation of mantle materials.

Granitic pegmatites contain natural concentrations of a variety of raw materials invaluable for modern technologies and a green and sustainable society. The most abundant ones are silicon for high-purity quartz applications, and indispensable lithium for today’s batteries. However, the exploration of these target materials in Europe is underdeveloped, causing high dependencies on non-European supply chains. The European Commission Horizon 2020 project GREENPEG (GA no. 869274) is addressing the exploration of buried, small-scale pegmatite deposits in Europe through the development of innovative new exploration toolsets. One component of these toolsets is petrophysical data of pegmatite ores and their wall rock. These data are essential to supplement and ground-truth non-invasive geophysical investigations and deposit modeling. Both important tools in mineral exploration can then be used in a more targeted and cost-effective way. Petrophysical parameters measured on drill core and field samples and acquired through geophysical borehole logging are compiled in the first database for European Pegmatite deposits: EuroPeg_PetroDB. Samples are supplemented with meta-information, and the database is comprehensively structured in an easy-to-use format. Supporting the initiative of FAIR data, EuroPeg is freely accessible on an open data repository. The sample content and petrophysical measurements are described, followed by the structure and usability of the database.

Niobium and tantalum are two rare metals that have similar physical and chemical properties and occur together in nature. They are considered to be strategic and critical materials for the economy and national security of many industrial countries. Both elements are on the 2022 List of Critical Minerals of the USA as well as on the European Union’s List of Critical Raw Materials. They rarely substitute for common elements in rock-forming minerals but are essential components in a range of rare minerals, particularly oxides and subordinately silicates. The economically important minerals are oxides. The columbite-tantalite and pyrochlore-microlite groups are the most common Ta- and Nb-bearing minerals. In Mongolia, primary niobium and tantalum mineralization includes two main types. The first type is mineralization associated with alkaline to peralkaline granites, pegmatites and syenites whereas the second type is related to the lithium-fluorine-rich peraluminous granites and related rocks (pegmatites and ongonites). The host rocks of both types of mineralization are the fractionated felsic rocks, which contain the primary magmatic ore assemblages associated with fractionation of magma rich in rare metals. Both assemblages were subsequently overprinted by the late magmatic to hydrothermal fluids, which remobilized and enriched the original mineralization. The newly formed ore mineral assemblages display complex replacement textures. In the case of peralkaline felsic rocks the processes produced the mineralization of Zr, Nb, heavy REE, Y, U, Th and Ta whereas peraluminous Li-F felsic rocks contain mainly mineralization of Sn, W, Ta, Li, and Nb. Mongolia hosts several promising occurrences of both types of Nb-Ta mineralization. However, they have not yet been sufficiently explored. Currently, the most promising is the occurrence in the Devonian Khalzan Buregtei peralkaline granites in northwestern Mongolia, where Nb-Ta is associated with REE and Zr mineralization. Mesozoic carbonatites of southern Mongolia do not host significant Nb and Ta mineralization.

Apatite can be used as an archive of processes occurring during the evolution of granitic magmas and as a pegmatite exploration tool. With this aim, a detailed compositional study of apatite was performed on different Variscan granites, pegmatites and quartz veins from the Central Iberian Zone. Manganese in granitic apatite increases with increasing evolution degree. Such Mn increase would not be related to changes in the fO2 during evolution but rather to a higher proportion of Mn in residual melts, joined to an increase in SiO2 content and peraluminosity. In the case of pegmatitic apatite, the fO2 and the polymerization degree of the melts seem not to have influenced the Mn and Fe contents but the higher availability of these transition elements and/or the lack of minerals competing for them. The subrounded Fe-Mn phosphate nodules, where apatite often occurs in P-rich pegmatites and P-rich quartz dykes, probably crystallized from a P-rich melt exsolved from the pegmatitic melt and where Fe, Mn and Cl would partition. The low Mn and Fe contents in the apatite from the quartz veins may be attributed either to the low availability of these elements in the late hydrothermal fluids derived from the granitic and pegmatitic melts, or to a high fO2. The Rare Earth Elements, Sr and Y are the main trace elements of the studied apatites. The REE contents of apatite decrease with the evolution of their hosting rocks. The REE patterns show in general strong tetrad effects that are probably not related to the fluids’ activity in the system. On the contrary, the fluids likely drive the non-CHARAC behavior of apatite from the most evolved granitic and pegmatitic units. Low fO2 conditions seem to be related to strong Eu anomalies observed for most of the apatites associated with different granitic units, barren and P-rich pegmatites. The positive Eu anomalies in some apatites from leucogranites and Li-rich pegmatites could reflect their early character, prior to the crystallization of feldspars. The increase in the Sr content in apatite from Li-rich pegmatites and B-P±F-rich leucogranites could be related to problems in accommodating this element in the albite structure, favoring its incorporation into apatite. The triangular plots ΣREE-Sr-Y and U–Th–Pb of apatites, as well as the Eu anomaly versus the TE1,3 diagram, seem to be potentially good as petrogenetic indicators, mainly for pegmatites and, to a lesser extent, for granites from the CIZ.

Sixty-seven sites of Hafafit pegmatite from the Southeastern Desert of Egypt were investigated radiometrically in the field using an in situ γ-ray spectrometer to determine eU, eTh, and K contents. The obtained results ranged from 0.4 to 6 ppm for eU with a mean value of 2.5 ppm, from 0.2 to 32 ppm for eTh with a mean value of 6.7 ppm, and from 0.7% to 5.4% for K with a mean value of 3.3%. Consequently, the radiological effects from these rocks were estimates by determination of the environmental parameters: gamma activity concentration index Iγ, external hazard index Hex, internal hazard index Hin, external absorbed dose rates in outdoor, and external absorbed dose rates in indoor air. The results obtained in this study showed that values U, Th, and K lie in the range of the acceptable world values. In addition, the calculated radiation hazard parameters (Iγ, Hex, and Hin) have values lower than the world values, while the calculated external absorbed dose rates (Dair) have values higher than the world and Egyptian permissible levels.

Eudialyte-group minerals are important accessory minerals of peralkaline rocks of nepheline-syenite massifs and alkaline–ultramafic complexes. Here, we report the complex study of a eudialyte-group mineral (EGM) from peralkaline pegmatite of the alkaline-ultrabasic Odikhincha massif (Polar Siberia). The chemical composition of the studied EGM is intermediate between those of taseqite and eudialyte, with small admixtures of other members of the eudialyte group. The crystals of EGMs were formed during the postmagmatic stage in the temperature range of 300–350 °C and partly replaced by late eudialite along cracks during the zeolite stage (~230 °C). The chemical compositions, structural features and mineral association of the studied EGM are similar to those of Sr-Nb-dominant EGM found in other nepheline-syenite massifs, such as Khibiny, Lovozero and Pilansberg. The EGM studied in this work is a Cl-deficient taseqite variety (“monochlore taseqite”), which differs from “dichlorotaseqite” (found only in the Ilimaussaq massif) by a lower amount of chlorine.

The mineralogical studies of rare-element (REL) pegmatites are important for unraveling the ore-forming process and evaluating REL mineralization potential. The Chinese Altai orogenic belt hosting more than 100,000 pegmatite dykes is famous for rare-metal resources worldwide and diverse REL mineralization types. In this paper, we present the results of EMPA and LA-ICP-MS for muscovite from the typical REL pegmatite dykes of the Chinese Altai. The studied pegmatites are Li-Be-Nb-Ta, Li-Nb-Ta, Nb-Ta, Be-Nb-Ta, Be and barren pegmatites. The Li+ accompanied with Fe, Mg and Mn substitute for Al3+ at the octahedral site in muscovite from the REL pegmatites, and the substitution of Rb by Cs at the interlayer space is identified in muscovite from the Be pegmatites. The P and B contents increase with evolution degree and the lenses from the Nb-Ta pegmatite are produced at late fluid-rich stage with high fluxes (P and B). The enrichment of HFSE in muscovite indicates a Nb-Ta-Sn-W rich pegmatite magma for the Be-Nb-Ta pegmatite. From barren pegmatite, beryl-bearing zone, to spodumene-bearing zone, the evolution degrees of pegmatite-forming magmas progressively increase. In the Chinese Altai, the possible indicators of muscovite for REL mineralization types include Rb (ca. 400–600 ppm, barren pegmatite; ca. 1200–4000 ppm, Be pegmatite; >4500 ppm, Li pegmatite), Cs (ca. 5–50 ppm, barren pegmatite; ca. 100–500 ppm, Be pegmatite; >300 ppm, Li pegmatite) and Ge (

Abstract The pegmatites of the São João del Rei Pegmatitic Province are related to the Siderian protoliths of the Cassiterita and Resende Costa orthogneisses and to the Ritápolis metagranitoid of Ryacian age. Chemical analysis of garnet from twelve pegmatites reveal two different types of grains, which were found in the same pegmatitic body in six of these samples. One garnet type has almandine-spessartine composition (Sps11-7-58.8 Alm36.8-86.5 Prp0.1-4.1Grs0.0-1.4Adr0.0-2.6), grains with orange and pink tones, and scarce mineral inclusions. These garnet grains may have been formed at the magmatic stage of pegmatite crystallization. The composition of these grains plot exclusively on the Alm-Sps axis at the Prp+Grs+Adr+Uvr × Alm × Sps diagram, as expected from garnet crystallized in pegmatites, and an expansion of the field associated to pegmatites is proposed. The second type has a distinct chemical composition (Sps26.9-84.8Alm3.6-40.0 Prp0.0-10.4 Grs9.3-45.6 Adr0.1-3.4), displaying enrichment in Ca. This Ca-enriched garnet has irregular shaped colourless grains and abundant mineral inclusions. These grains may have been formed by Ca-metasomatism during the late-stage crystallization of the pegmatites.

The inclusion of native trees in mine land reclamation has been promoted over the years yet that of highvalue multipurpose species for people’s livelihoods has been overlooked. Also, studies utilizing human excreta (HE), i.e. fecal matter, (FM) and human urine fertilizer HUF), and wood ash (WA) in land reclamation are scarce. Yet, these are indispensable in areas with a limited supply of organic materials and high demand for natural resources. This study evaluated the effects of HE and WA on the growth and establishment of Ficus thonningii Blume (ficus) in a pegmatite-rich tantalum Technosol. Hardwood cuttings of ficus from homesteads in Western Rwanda were planted in 20.4 × 19 cm diameter pots containing 5 kg forest soil (FS) and 6 kg Technosol. Five treatments including No amendment; HUF alone (100 mL/pot); HUF+WA (100 mL + 60 g/pot); FM (200 g/pot); and FM+WA (200 g + 60 g/pot) were prepared in ten replicates each. Plant height, number of leaves, shoot and root biomass were determined after five and seven months after planting. The HE and WA treatments significantly increased (P = 0.003) ficus height (FS = 39 – 42 cm and Technosol = 31 – 34 cm) after seven months. Shoot biomass weights ranged from 17 – 21 g in the FS and 10 – 16 g in the Technosol. Ficus exhibited an efficient rooting system that stabilized the loose particles of the Technosol, suggesting the potential of using ficus, HE, and WA in degraded mine soil reclamation in future research. Keywords: Fecal matter; Human urine fertilizer; Root and shoot biomass; Pegmatite

Most of the rare metal pegmatite deposits in China lie in West, Central and South China, and the Lijiapuzi Nb-Ta deposit is the only pegmatite-type Nb-Ta deposit in Northeast China, therefore a detailed study of the Lijiapuzi deposit is of great importance to the metallogeny and exploration of rare metal deposits in Northeast China. The Nb-Ta bearing pegmatites in Lijiapuzi district are composed of a microcline wall zone, a muscovite (lepidolite)-albite intermediate zone and a quartz core, and the rare metal mineralization mainly occurs in the intermediate zone and is intimately related to the albitization. The lithogeochemical features indicate that Lijiapuzi pegmatoids are rich in silicon and alkaline, poor in calcium, magnesium, titanium and phosphorus, and belong to peraluminous granitoid rocks. The enrichment of large ion lithophile elements (LILEs) and depletion of high field-strength elements (HFSEs), the distinct right-inclined REE pattern with obvious Eu negative anomaly, lower ratio of Nb/Ta and higher ratio of La/Nb and Rb/Sr indicate that the pegmatite was of a crustal origin and formed in relatively extensional tectonic setting of post-orogenesis. The pegmatites in Lijiapuzi area can be divided into two categories, i.e., the NW-trending pegmatites are shorter and thicker, with obvious zoning and localized in the upper part of the near-surface, while the NE-trending pegmatites are longer, thinner, devoid of zoning and localized in the lower part of the district. This probably means that excellent ore prospecting potential exists in the lower part of the Lijiapuzi district.

Experimental studies increasingly often report low-temperature (200–800 °C) and low-pressure (0.05–3 kbar) hydrosilicate fluids with >40 wt.% of SiO2 and >10 wt.% of H2O. Compositionally similar fluids were long suggested to potentially exist in natural systems such as pegmatites and hydrothermal veins. However, they are rarely invoked in recent petrogenetic models, perhaps because of the scarcity of direct evidence for their natural occurrence. Here we review such evidence from previous works and add to this by documenting inclusions of hydrosilicate fluids in quartz and feldspar from Itrongay. The latter comprise opal-A, opal-CT, moganite and quartz inclusions that frequently contain H2O and have negative crystal shapes. They coexist with inclusions of CO2- and H2O-rich fluids and complex polycrystalline inclusions containing chlorides, sulphates, carbonates, arsenates, oxides, hydroxides and silicates, which we interpret as remnants of saline liquids. Collectively, previous studies and our new results indicate that hydrosilicate fluids may be common in the Earth’s crust, although their tendency to transform into quartz upon cooling and exhumation renders them difficult to recognise. These data warrant more comprehensive research into the nature of such hydrosilicate fluids and their distribution across a wide range of pressure and temperature conditions and geological systems.

The Jiajika rare-metal deposit located in western Sichuan Province (China) is renowned as the largest lithium deposit in Asia, and the No. 134 pegmatite dike is the largest lithium pegmatite under mining conditions in the area. On the basis of a detailed characterization of textures and minerals in the Jiajika No. 134 pegmatite, two zones (the barren Zone I and the spodumene Zone II) and three subzones (Zone II was subdivided into microcrystalline, medium-fine grained and coarse-grained spodumene zones) have been identified. The detailed mineralogical characteristics of lithium minerals and other indicator minerals from each zone were evaluated by EPMA for illustrating the magmatic–hydrothermal evolution and the cooling path of the Jiajika No. 134 pegmatite. From the outer zone inwards, grain size gradually increased, the typical graphic pegmatite zone was absent, and spodumene randomly crystallized throughout nearly the whole pegmatite body. This evidence indicated a Li-saturated melt prior to pegmatite crystallization, which could be the main cause of the super-large-scale Li mineralization of the Jiajika No. 134 pegmatite. A comparison of the Cs content between primary beryl in the Jiajika No. 134 pegmatite and other important Li-Cs-Ta pegmatites in the world indicates that No. 134 pegmatite shows a high degree of fractional crystallization. The evolution of mica species from muscovite to Li-micas from Zone I to Zone II marks the transition from the magmatic to the hydrothermal stage in pegmatite evolution. The absence of individual lepidolite and the relatively limited scale of alteration of spodumene (

The existence of diagnostic features in the visible and infrared regions makes it possible to use reflectance spectra not only to identify mineral assemblages but also for calibration and classification of satellite images, considering lithological and/or mineral mapping. For this purpose, a consistent spectral library with the target spectra of minerals and rocks is needed. Currently, there is big market pressure for raw materials including lithium (Li) that has driven new satellite image applications for Li exploration. However, there are no reference spectra for petalite (a Li mineral) in large, open spectral datasets. In this work, a spectral library was built exclusively dedicated to Li minerals and Li pegmatite exploration through satellite remote sensing. The database includes field and laboratory spectra collected in the Fregeneda–Almendra region (Spain–Portugal) from (i) distinct Li minerals (spodumene, petalite, lepidolite); (ii) several Li pegmatites and other outcropping lithologies to allow satellite-based lithological mapping; (iii) areas previously misclassified as Li pegmatites using machine learning algorithms to allow comparisons between these regions and the target areas. Ancillary data include (i) sample location and coordinates, (ii) sample conditions, (iii) sample color, (iv) type of face measured, (v) equipment used, and for the laboratory spectra, (vi) sample photographs, (vii) continuum removed spectra files, and (viii) statistics on the main absorption features automatically extracted. The potential future uses of this spectral library are reinforced by its major advantages: (i) data is provided in a universal file format; (ii) it allows users to compare field and laboratory spectra; (iii) a large number of complementary data allow the comparison of shape, asymmetry, and depth of the absorption features of the distinct Li minerals.

The Ningshan pegmatite district in the South Qinling Orogen hosts numerous Rb-(Be) mineralized pegmatites. In this study, whole-rock geochemistry, mineral geochemistry, and zircon U–Pb isotopes of the Rb-rich and barren pegmatites were determined. The barren pegmatites consist mainly of muscovite, microcline, albite, quartz, and garnet, whereas the Rb-rich pegmatites are mainly composed of muscovite, albite, quartz, and beryl, with minor chrysoberyl, cassiterite and columbite-group mineral. The muscovite and albite are the main Rb-bearing minerals. The U–Pb zircon dating of the Rb-rich and barren pegmatites yielding an age of 212–203 Ma, which is similar to that of the neighboring two-mica monzogranites distributed in the Ningshan area. Compared with the two-mica monzogranites, geochemical features, such as the Zr/Hf, Rb/Sr and Nb/Ta ratios and trace element contents indicated that the Rb-rich and barren pegmatites derived from fractionation of the two-mica monzogranites. In combination, the current and previous results suggest that the fractionation of the two-mica monzogranites caused the generation of the affinitive residual melts that, finally, crystallized to form the pegmatites. Compared to those from the barren pegmatites, the apatite from the Rb-rich pegmatites have higher MnO (14.51–19.12 wt.%) and Cl (0.12–0.16 wt.%) contents and lower F/Cl rartios (20–29). We conclude that these differences reflect unique geochemical signatures, and the geochemical composition of the apatite can be used as exploration guidance for rare metal-rich pegmatites.

Optical and thermal remote sensing data have been an important tool in geological exploration for certain deposit types. However, the present economic and technological advances demand the adaptation of the remote sensing data and image processing techniques to the exploration of other raw materials like lithium (Li). A bibliometric analysis, using a systematic review approach, was made to understand the recent interest in the application of remote sensing methods in Li exploration. A review of the application studies and developments in this field was also made. Throughout the paper, the addressed topics include: (i) achievements made in Li exploration using remote sensing methods; (ii) the main weaknesses of the approaches; (iii) how to overcome these difficulties; and (iv) the expected research perspectives. We expect that the number of studies concerning this topic will increase in the near future and that remote sensing will become an integrated and fundamental tool in Li exploration.

The increasing demand for green technology and battery metals necessitates a review of geological exploration techniques for Li−Cs−Ta (LCT) pegmatites, which is applicable to the work of mining companies. This paper reviews the main controls of LCT pegmatite genesis relevant to mineral exploration programs and presents a workflow of grassroots exploration techniques, supported by examples from central Europe and Africa. Geological exploration commonly begins with information gathering, desktop studies and Geographic Information System (GIS) data reviews. Following the identification of prospective regional areas, initial targets are verified in the field by geological mapping and geochemical sampling. Detailed mineralogical analysis and geochemical sampling of rock, soil and stream sediments represent the most important tools for providing vectors to LCT pegmatites, since the interpretation of mineralogical phases, deportment and liberation characteristics along with geochemical K/Rb, Nb/Ta and Zr/Hf metallogenic markers can detect highly evolved rocks enriched in incompatible elements of economic interest. The importance of JORC (Joint Ore Reserves Committee) 2012 guidelines with regards to obtaining geological, mineralogical and drilling data is discussed and contextualised, with the requirement of treating LCT pegmatites as industrial mineral deposits.

Core of the Moslavačka Mt. is built of S-type granite and granodiorite, wrapped up in migmatites. Outer zone is represented with metamorphites of amphibolite facies. The Moslavačka Mt. is a product of regional metamorphism on Lower Paleozoic pelito-psammitic protholite. Numerous quarries exploited granite, amphibolite, gabbro, orthogneiss. Stronger concentrations of sillimanite, andalusite, cordierite, garnet, and tourmaline were observed in different types of rocks. The pegmatite phase generated veins and irregular boddies of metasomatic-injected pegmatites with garnet and tourmaline. Hydrothermal quartz veinlets with sulphides have only mineralogical significance. Migmatites and S-granites form central parts of the Slavonian Mts. Dating gave age of 314-333 Ma (Namurian-Westphalian). Metaclastites of lower metamorphic sequences contain palynomorphs from Silurian to the Lower Carboniferous. Graphitite deposits generated by regional metamorphism were exploited in the mines Brusnik, Sivornica and Brezovo Polje in the Psunj Mt. and in the mine Kapitol in the Papuk Mt. Numerous metasomatic injected pegmatites were exploited on the locations Veliki and Mali Debeljak, Točak, Bilo, Lom and quartz veins at Zavlaka and Motičina Gornja. Postcollisional I-granites gave a small volastonite skarn deposit in the Kiseljevački brook. Mineralogical occurrences of hematite, pyrite, asbestos and copper are genetically bounded with diabases. Talc-chlorite schists were exploited in the mine Koprivna (Psunj). Longlasting investigations of sedimentary uranium occurrences were negative. The best results were obtained in the Kaptol, Cipalovac and Ninkovac brooks. In the alluvium of numerous brooks more significant quantities of gold, monazite, rutile, zircon and scheelite were found (the paper is published in Croatian).

Kristiansenite, ideally Ca2ScSn(Si2O7)(Si2O6OH), a rare late-stage hydrothermal Sc-bearing sorosilicate mineral, was found in a gadolinite-fergusonite-type pegmatite of the MI-REE subclass related to the Karkonosze granite, exposed in a quarry at Szklarska Poręba, Lower Silesia, Poland. Kristiansenite occurs in an association with andradite, epidote, allanite-(Ce), titanite, fersmite, scheelite, Sc-bearing columbite-(Fe), a YNbO4 mineral as fergusonite-(Y) or fergusonite-(Y)-beta, silesiaite and wolframite. Single-crystal study of the mineral (R1 of 4.96%), with composition Ca2.00(Sn0.97Sc0.69Fe3+0.17Mn0.05Ti0.04Zr0.03Nb0.02Al0.02Ta0.01)Σ2(Si2O7)[(Si1.98Al0.02)Σ2O6.03(OH)0.97], corroborates its triclinic structure with space group-symmetry C1, Z = 2, and unit-cell parameters a = 10.0304(5), b = 8.4056(4), c = 13.3228(6) Å, α = 90.001(3), β = 109.105(3), γ = 89.997(3)° and V = 1061.40(9) Å3. In the structure of the mineral, the Ca and Si sites are dominantly occupied with Ca and Si, whereas the M1⁻M4 sites are disordered. The M3 and M4 sites are occupied dominantly by Sn and subordinately Sc, whereas the M1 and M2 sites are occupied dominantly by Sc and subordinately by remaining occupants, including Sn.

Pegmatite is the main source of feldspar for ceramics industry. Usage of pegmatite in ceramic industry causes some problems due to the presence of mica and iron oxides. These materials reduce tile strength, hardness and density of the final product leading to low quality ceramic products. Southern Saudi pegmatite separation treatment was carried out in two phases in order to improve the ceramic quality of the feldspar obtained from this pegmatite. The first phase consists of gravitational separation to remove the heavy impurities and in the second phase magnetic separation was carried out to further minimize iron content. Porcelain ceramic batches were prepared by wet-mixing, drying, pressing (semi-dry press) and fired at temperatures from 1000 to 1350 °C. The porcelain ceramic bodies were prepared and examined by DTA, X-ray diffraction, SEM and tested for bulk density, linear shrinkage, water absorption and flexural strength. These results indicated that, after treatment (gravity and magnetic separation), the pegmatite can be considered as a good source of potash feldspar. The present study provides a positive indication for using of Southern Saudi pegmatite after treatment in ceramic industries.

Two types of halloysite collected from the upper (UPS) and lower (LOS) zones of a weathered pegmatite profile in the Thach Khoan area, Phu Tho were defined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermal analysis (TG and DTG), and N2 adsorption-desorption isotherms. XRD analysis showed that halloysite and kaolinite coexist in samples of size fractions 100 nm constitute 79.1% of halloysites in the UPS sample while long halloysites with outer diameter of 50–100 nm make up 74.2% of halloysites in LOS sample. Specific surface areas are 15.7434 and 22.0211 m2/g and average pore sizes are 18.9837 and 17.0281 nm for the UPS and LOS samples, respectively. The analysis implies that although forming under same natural geographical and climatic conditions, halloysites at different depths in the weathered pegmatite profile may have different morphological and other properties.

- Kaymaz (Sivrihisar) Eskişehir ilinin 80 km dogusunda yer almaktadir. Çalişma sahasi metamorfitler, ofiyolitler, fonolitler ve pegmatitten oluşmaktadir. Bu birimlerden metamorfitleri kesen dere sedimanlarinda beril kristallerinin varligi belirlenmiştir. Toplanan örneklerde en fazla 35 µm boyutunda, yeşil ve açik yeşilimsi mavi renkli beril taneleri hekzagonal yapili, bazal dilinimli, no= 1.584, ne= 1.568 işik kirma indisleri, tek optik eksenli (-) ve SEM de özşekilli hekzagonal prizmatik karakterli özellikler göstermektedir. Jeokimyasal olarak fonolit örneklerinde Be içerigi (9-31 ppm), pegmatitlerde (4-17 ppm) ve metamorfiklerde ise 1 ppm tespit edilmiştir. Fonolitlerde berilyumla ilişkili elementlerden F (260-440 ppm), Ba (1088-3106 ppm), La (300 ppm), Y (16-19 ppm), pegmatitlerde F (300 ppm), W (10 ppm) ve Sn (5 ppm) degerleri göstermesi ve beril kristallerinin fonolit ve pegmatitlerle tektonik ilişkili olan metamorfik kayaçlari kesen dere sedimanlarinda belirlenmesi berilin oluşumunun kökensel olarak bu kayaçlarla bagintili oldugunu göstermektedir

The Artjärvi and Sääskjärvi granite stocks at the western margin of the Wiborg rapakivi batholith are multiphase rapakivi granite intrusions in which the most evolved phase is topaz-bearing granite. The Artjärvi stock is composed of porphyritic and even-grained biotite granite and even-grained topaz granite, and the Sääskjärvi stock comprises even-grained biotite granite and porphyritic topaz granite. The granites are metaluminous to peraluminous A-type granites, showing within-plate (WPG) geochemical characteristics. The topaz granites from the Artjärvi and Sääskjärvi stocks are petrographically and geochemically similar to other topaz-bearing rapakivi granites in Finland. The anomalous geochemistry of the topaz granite is essentially magmatic; postmagmatic reactions have only slightly modified its composition. Greisen veins, some of which are mineralized, are widely found associated with the Artjärvi and Sääskjärvi stocks. The most characteristic feature of the Artjärvi granite stock is a stockscheider at the roof contact of the topaz granite. The stockscheider is composed of schlieren layering and pegmatite layers parallel to the contact. The most probable mechanism for the formation of the schlieren layering is velocity-gradient sorting parallel to the flow, which led to accumulation of mafic minerals along the upper contact of the topaz granite. Cooling and contraction of the topaz granite formed fractures parallel to the roof contact and the residual pegmatite magmas were injected along the fractures forming pegmatite layers. Textures like graphic intergrowths, aplitic groundmass and fan-shaped alkali feldspar crystals associated with the Artjärvi porphyritic biotite granite and pegmatite indicate crystallization from undercooled magma. Miarolitic cavities found in the porphyritic biotite granite and topaz granite indicate at least local volatile saturation.

The Gross Spitzkoppe granite stock (GSS) is a zoned 30 km2 epizonal intrusion that consists of three main granites: 1) medium-grained biotite granite (marginal), 2) a coarse-grained biotite granite, and 3) a central, porphyritic granite. The stock contains pegmatites as banded marginal stockscheiders and isolated pockets composed of large alkali feldspar and quartz, dark mica, interstitial fluorite, and euhedral topaz and beryl crystals. In the porphyritic granite there are local wolframite-bearing greisens and hydrothermal fluorite and topaz-rich veins. Fluid inclusion studies were conducted on: 1) topaz and quartz crystals from the marginal stockscheider; 2) quartz, topaz, fluorite and beryl crystals from isolated pegmatites; 3) topaz from a miarolitic pegmatite; 4) beryl and quartz veins from greisenized porphyritic granite; and 5) fluorite from a late fluorite vein in the coarse-grained biotite granite. Preliminary data indicate the presence of three compositionally distinct primary and pseudosecondary inclusion types that are of late magmatic-hydrothermal origin. Type 1. Low salinity (0–10 eq. wt% NaCl) H2O (± CO2) inclusions that homogenize to the liquid phase in the temperature range of 300 to 550°C. These inclusions are from quartz, topaz and beryl. Inclusions in fluorite from the fluorite vein homogenize at ~170°C and have a salinity of ca. 1–2 eq. wt% NaCl. Type 2. Saline (25–30 eq. wt% NaCl) halite-bearing H2O (± CO2) inclusions that homogenize to the liquid phase in the temperature range of 300 to 400°C. These inclusions are from quartz. Type 3. Low salinity (0–3 eq. wt% NaCl) H2O-CO2 inclusions that homogenize to vapor phase in the temperature range of 330 to 550°C. These inclusions are from quartz and topaz. Hydrothermal fluids from greisen minerals are represented by type 1 and type 2 H2O inclusions. They are predominantly of low salinity (~8 eq. wt% NaCl) and homogenize to the liquid phase in the temperature range of 300 to 500°C. Isochores for contemporaneous type 2 and type 3 inclusions with homogenization temperature range of 330 to 400°C indicate a maximum trapping pressure of about 900 bar for the marginal stockscheider.

Rubidium feldspar occurs near the core zone of the highly fractionated petalite-subtype Luolamäki granitic pegmatite in intimate intergrowth with other feldspars which are part of a characteristic sequence of alteration of pollucite. Pods of pollucite are cut by 5-20 cm-wide veins of albite, petalite, non-perthitic microcline, lepidolite and quartz, by thinner veins of fine-grained micas and spodumene, and are replaced by metasomatic adularia. Grains of rubidium feldspar occur as a potentially ordered phase in the vein microcline in association with earlier-exsolved albite, and also as late thin (< 5 μm) veinlets. Rubidium feldspar also occurs as a potentially disordered phase which crystallized along with metasomatic adularia. Both generations of (Rb,K)-feldspar have a similar compositional range, close to the join KAlSi3O8-RbAlSi3O8, typically with up to ~21 wt.% Rb2O (~70 mol.% Rbf) and with minor Cs, but neglible Na, Ca, Fe or P. Extreme compositions have 26.0 wt.% Rb2O (89.0 mol.% Rbf) and 1.26 wt.% Cs2O (2.8 mol.% Csf). The diffuse compositional gradients from microcline to rubicline are consistent with a solid-state exsolution origin, followed by fluid-assisted textural coarsening which generates distinct phase boundaries. In contrast, metasomatic adularian (Rb,K)-feldspar was precipitated at low temperature (250-150°C) and fine-scale zoning with variable K/Rb is preserved as a growth feature.

The thick-target PIXE technique was applied to direct analysis of trace elements in tourmaline minerals. Analyses of these minerals with conventional wet-chemical methods are difficult and time consuming. The PIXE analyses were carried out in air with a collimated proton beam. As the technique was used in combination with a polarizing microscope it provided excellent control over the spots analyzed. A scanning device was developed for remote-controlled spot analyses across the surface of the samples. Several scans were run across polished sections of multicrystal schorl-tourmaline aggregates. Pellets of crushed and ground tourmaline samples were also analyzed. The method was calibrated against USGS standard reference materials. The precision of the method varied between 1 and 10 % and the detection limits were 1-10 ppm for most of the elements analyzed. Different sets of X-ray absorbers were used to improve the sensitivity and reliability of the method for the elements of interest. The concentrations of fourteen elements were calculated from their X-ray yields and the fluorine content was simultaneously determined using the 109.8 keV gamma line. The tourmaline samples were taken from a complex granite pegmatite on the Kimito island in SW Finland. They were found to contain mainly elements with Z < 33 (lighter than As). Relatively high concentrations of Fe, Zn, Ga and F were observed. Zinc was found to be a geochemically important minor element in schorl with a concentration ranging from 0.10 to 0.28 %. The pellets were found to contain inclusions of other minerals.