Mica Minerals Research Articles

Ground-truthing of a data driven landform map in southwest Australia

A variety of data driven, mostly supervised, machine learning approaches have been used to model landforms in soil and regolith sciences, commonly with a claim of enhanced objectivity of the resulting map. These models regularly rely on soil sample measurements or existing human derived mapping products to train or retrospectively validate a model. Case studies of unsupervised machine learning approaches are less common, and input data as well as clustering algorithms vary widely. In this study, a relatively simple, unsupervised machine learning approach was used to create a proxy landform map from partially independent, remotely-sensed data (digital elevation model, radiometric U, Th and K, Sentinel-2 derived band ratios, and Multi-resolution Valley Bottom Flatness). This machine learning workflow was developed for general, first-pass landform mapping in remote areas, where access is limited, to provide tools for mineral exploration. The workflow was designed for the Australian continent and previously applied to over 40 sites. However, given that the models were not trained or retrospectively validated with objective observations, the question arises whether the units identified represent meaningful differences in soil and landform properties. To answer this question, conditioned Latin Hypercube Sampling was used to identify sampling locations that capture the variability of properties of eight landform clusters produced from a machine learning workflow in the Mundaring State Forest, Western Australia. Soil cores (30 cm depth) were sampled at these 40 sites, and we combine portable X-ray fluorescence, visible near-infrared to shortwave infrared analyses, soil pH and field observations to identify differences between the modelled landform types, and how the soil physico-chemical and mineralogical properties relate to the model’s input feature layers. Our investigations show that the model produced largely contiguous landform units with distinctive differences that were reflected in measurable averages of geochemical and mineralogical soil properties. As such, highest Si concentrations correlated with sandy channel materials while Mn and Fe concentrations were highest in ferruginous duricrust, and white mica and chlorite group minerals were identified in shallow residual soils developed from granitic parent material. These results correlate well with the model input features and align with a general conceptual understanding of soil-landscape and regolith landform formation, and with existing soil and regolith maps. However, some inconsistencies were observed in the landform unit clusters, likely capturing the heterogeneity of the landform/soil and this provides an understanding of the limitations of categorical models.

Structural-crystallochemical features of minerals of the glauconite-illite series with high Mg contents from Upper Proterozoic deposits of Eastern and Northern Siberia

At the current level of research, a generalization of previously studied and new lithological-mineralogical and structural-crystal-chemical characteristics of globular phyllosilicates (GPS) of the glauconite-illite series with a high Mg content from Upper Proterozoic sections of Eastern and Northern Siberia (Uchur-May region, Anabar uplift) has been carried out. The classification of glauconite-illite minerals was carried out in accordance with the recommendations of the International Nomenclature Committees for mica and clay minerals, as well as on the basis of literature and our own data. The degree of aluminum content of minerals (КAl = VIAl / [VIFe3+ + VIAl]) of the glauconite-illite series varies from 0.40 to 0.85, the content of Mg and K cations varies from 0.51 to 0.75 and from 0.63 to 0.80 f.u. (formula units), respectively. Using X-ray modeling method of diffraction patterns of oriented and non-oriented preparations of Upper Proterozoic GPS, the following were determined: the content of swelling layers (4–10%), their types (mica, smectite, chlorite), the nature of the alternation (short-range order factor R = 0), unit cell parameters csinβ, ccosß/a, average value of parameter b (9.018–9.074 Å). The conditions of glauconite formation in the Upper Proterozoic basins are considered, their influence on the structural and crystal-chemical features of magnesian hydrocarbons is discussed.

Identification of Gold targets using airborne geophysics and remote sensing data in part of northcentral Nigeria

The exploration and utilization of economic mineral deposits are of paramount importance in driving the prosperity and progress of nations across the globe. An integrative approach of integrating aeromagnetic, airborne-radiometric, and remote-sensing methods was employed to assess gold mineralization zones within Paiko town in Niger state, northcentral Nigeria. Airborne-radiometric and remote-sensing datasets were utilized to map subsurface structures, lithological units, and hydrothermal alteration zones. The investigation delineated three major tectonic events along different directions: the ENE-WSW (D1) trending tectonic event, the WNW-ESE (D2) trending tectonic event, and NW-SE (D3) trending structural deformation event. The three deformation phases signify unique magnetic unit boundaries, lithological contacts, veins, and veinlets intrusions. These structures were interpreted as potential pathways for mineralization fluids. Moreover, the presence of high potassium-rich zones with low thorium/potassium ratio anomalies indicated potassium enrichments associated with sericite mica and K-feldspar minerals. The study also mapped various alterations of ferrous silicates, holding the potential to host gold and copper deposits, as well as endoskarn, epidot/chlorite/amphibole alterations, and phyllic minerals. Depth estimates derived from magnetic source parameters imaging techniques revealed that the mineralization targets in the area are relatively shallow, with depths ranging from the near-surface to less than 100 m. The delineation of mineralization zones in the study area convincingly demonstrates the effectiveness of integrating airborne geophysical and remote sensing data for exploring, developing, and managing subsurface mineral resources. This approach provides valuable insights into gold mineralization's presence, distribution, and characteristics, facilitating informed decision-making in mineral resource exploration and utilization.

Lithological and Structural Mapping of Basement Rock Units in the Ikara North-Central Basement Complex, Nigeria

Study’s Excerpt The lithological and structural composition of the Ikara North-Central Basement Complex in Nigeria is investigated. Detailed field and petrographic analyses were carried out to identify the rock types of the area. The geological map of the area is updated. Full Abstract The lithological and structural architecture to unravel the compositions and tectonic evolution of the Nigerian Basement Complex has not been fully documented by geoscientists. As such, this research aimed to investigate the lithological and structural characteristics of the Ikara North-Central Basement Complex. Detailed petrographic and field analysis reveals the prevalence of gneiss and granite lithologies characterized by significant structural features such as fractures, folds, and foliations. These findings offer new understandings of the tectonic evolution of the region. The study area mapped is the Ikara Sheet 103 Federal Survey Topographic Sheet to a scale of 1:100,000. The major lithological units underlying the study area are gneisses and granites. However, these major rock types have varieties, namely migmatitic gneiss, granite gneiss, migmatitic (augen) gneiss, porphyroblastic gneiss, medium to coarse-grained granites, and porphyritic granites. These rock types were intruded by quartzites, pegmatitic dykes, quartz, and aplite veins. Rock samples were observed and studied based on their mineralogical composition, color, and texture. The results of the petrographic analysis showed that the rocks are mainly composed of quartz, plagioclase feldspars, alkali feldspars, mica (biotite and muscovite), hornblende, garnet, and accessory minerals like zircon and magnetite. Geological structures were also observed during the field study, namely fractures (joints and fractures), foliations, lineations, veins, dykes, and various landforms. Photomicrographs from thin section analyses revealed micro-structures like myrmekites, micro-folds, and micro-fractures were also observed. Mineralization such as amethyst and cassiterite were hosted by quartz veins and pegmatites in porphyritic granites, respectively. A litho-structural map was produced, exhibiting the lithological units and regional structures cross-cutting the area of research.

The Effect of the Topolitosequnces on The Mineral Properties of Some Soils of Sulaymaniyah Governorate / Kurdistan Region

This study was conducted to determine the effect of different parent materials and topography on the mineral composition Sulaymaniyah Governorate was chosen as a site for its conduct. Select transact of study within the Bazian Plain extending from the Bazian Heights in the west to the Taslujah Heights in the east. The results were: The predominance of clay minerals is chlorite > smectite > mica > Interstratified minerals > kaolinites. The predominance of the minerals chlorite, smectite, and mica in the clays of these soils is mainly due to the influence of their parent material (limestone, limestone, Maral), especially within Pedons, the high areas at both ends of the aforementioned study transect (Taslujah, Bazian), whose parent material consisted of rocks. (Limestone and limestone-Maral) respectively. While the dominance of mica minerals within the soils of the plains of the plain region is due to the influence of the source material, slope, topography, and distance from high ends.

Age and petrogenesis of the Madi intrusion in the Huashi area, northern margin of the North China Craton: Implications for magma evolution and Nb–Ta mineralization

Although the mineralization of rare earth elements (REEs) and rare metals is intimately associated with the extreme fractionation of granitic magmas, the metallogenic intrusions of many granite-hosted Nb–Ta deposits have undergone fluid–melt interaction. Nevertheless, the precise mechanisms by which fluid–melt interaction influences mineralization remain poorly understood. The present investigation examines the issues of the fluid–melt interaction in highly fractionated granites with Nb–Ta mineralization, utilizing data from the newfound Huashi deposit in the northern margin of the North China Craton (NNCC). The Huashi Nb–Ta–Rb–Li deposit hosted in the Madi intrusion consists of two lithologies that have evolved continuously, namely medium–fine grained granite (MGG) in the lower section and alkali-feldspar granite (AG) at the top. The ages of the MGG and AG were determined using LA–ICP–MS columbite U–Pb dating, yielding values of 182.9 ± 1.7 Ma and 184.7 ± 1.3 Ma, respectively. The Madi intrusion has high SiO2, Al2O3, and total alkali contents, along with low CaO, MgO, MnO, and TFe2O3 contents and high Al2O3 / (CaO + Na2O + K2O) (A/CNK) values, classifying it as highly peraluminous granite with a high-K calc-alkaline affinity. Additionally, the intrusion also exhibits enrichment in Rb, U, Th, and Nb alongside significant depletion in Sr, Ba, Ti, Eu, and P, with a noticeable tetrad effect of REEs. The investigation of mica and feldspar minerals in the Madi intrusion using electron probe microanalysis (EPMA) indicates that the mica is mainly zinnwaldite, while the plagioclase belongs to albite. In summary, the Madi intrusion exhibits a highly I-type fractionated granite affinity. The extreme fractionation, intense fluid–melt interaction, and hydrothermal alteration of the intrusion contribute to the formation of the Huashi deposit.

Alteration Zones as Exploration Parameters for Stratiform Pb-Zn-Ag-Ba Deposits in the Graz Paleozoic (Eastern Alps, Austria)

AbstractIn the Graz Paleozoic in the Eastern Alps (Austria), stratiform Pb-Zn-Ag-Ba deposits have been mined in the past. They are classified as sedimentary-exhalative (SEDEX) deposits and are hosted by polyphase deformed greenschist facies metasediments and volcanics of the Schönberg Formation (Schöckel nappe; Drauzug-Gurktal nappe system), which is upper Silurian to Lower Devonian in age. The stratiform ore horizons are dominated by galena, sphalerite, barite, pyrite, pyrrhotite, and magnetite and are accompanied by chalcopyrite, arsenopyrite, fahlore, pyrargyrite, tetradymite, cobaltite, ullmannite, breithauptite, electrum, and others. The project MRI_SEDEXPOT investigates these deposits to evaluate their exploration potential by focusing on hydrothermal alteration zones occurring in the footwall and hanging wall of the ore. Such alteration zones are globally used as exploration tools not only for SEDEX deposits. The investigated alteration zones show distinct mineralogical and geochemical characteristics. They contain Fe rich carbonates and chlorite, K‑ and Ba-feldspars, Ba bearing white mica, fluorapatite, REE and HFSE minerals. Disseminated sulphides are widespread, and albitization is typical below sulphide rich horizons. Geochemical profiles correlate well with the observed mineralogy. Ongoing investigations of these alteration zones should lead into defining proximity indicators to the ore and evaluation of the exploration potential of the stratiform Pb-Zn-Ba-Ag deposits of the Graz Paleozoic.

Study on Production Characteristics and Change in Production Location of Pottery Excavated from DongOe-dong Site in Goseong

As a result of scientific analysis of 26 pottery excavated from the DongOe-dong site in Goseong, pottery with various firing degrees was confirmed, ranging from low-firing pottery with mica minerals detected to high-firing pottery with high-temperature minerals such as cristobalite and mullite detected. In addition, low-firing pottery has an absorption rate of 9.7∼25.8% and generally shows high saturation value. On the other hand, high-firing pottery has low absorption rate and saturation value, so the physical characteristics of the pottery show a high correlation with the group classified by XRD analysis. Pottery with a low firing degree commonly contains fine-grained mineral particles and has a similar composition of trace elements such as Rb, Ba, and Sr. And they were most abundantly excavated from the No. 1-1 moat. However it was confirmed that there is a difference in the production area because compositions of the rare earth elements are distributed in two areas in the graph. High&intermediate-firing pottery samples are observed to have a vitrified base matrix and relatively less temper minerals. And their contents of Rb, Sr, and Ba are significantly different from low-firing pottery. In the composition of rare earth elements, they are all distributed in same area as one of the separated areas of low-firing pottery, so it is highly likely these pottery were produced in the same or nearby production region regardless of the firing degree. As a result of checking up the composition of rare earth elements according to the archaeological chronology of pottery, it is estimated that there was a change in the production region of the pottery introduced into the DongOe-dong site around 250 AD.

2D to 3D Magnetism in Synthetic Micas.

Fe-based mica minerals usually display two opposing magnetic ground states, either they behave as spin-glasses or as layered ferrimagnets. No definite reason has been proposed as an explanation for this duality. This conundrum is unraveled by comparing the synthetic micas KFe3[MGe3]O10X2 with M═Fe and Ga, X═OH- and F-. Neutron diffraction demonstrates a 2D to 3D magnetic transition in KFe3[FeGe3]O10(OH)2 while just hints or no order at all are observed for the fluorides with M═Fe and Ga respectively. The 3D transition is triggered by the presence of iron in the intralayer tetrahedra. DFT+U calculations show that the magnetic exchange couplings between the previously believed solely magnetic octahedral layers would otherwise be frustrated without this intralayer iron.

Tellurium Enrichment in Copper Tailings: A Mineralogical and Processing Study

As the global demand for tellurium (Te) increases, it is crucial to develop efficient recovery methods that consider existing supply streams. This research combines gravity separation and froth flotation processes to enhance the recovery of Te minerals from tailings produced during the beneficiation of copper porphyry ores. Prior to processing, a systematic and comprehensive characterization study of copper tailing (CT) samples was conducted to examine the deportment of Te minerals in different mineral phases and to understand their locking and liberation behavior. Characterization techniques included inductively coupled plasma mass spectrometry (ICP-MS) and TESCAN’s integrated mineral analysis (TIMA). Copper tailing characterization showed that minerals with gold (Au), silver (Ag), bismuth (Bi), and Te were present in various forms, including native Au, electrum, tellurides, and sulfosalts. TIMA revealed that >90% of these minerals were primarily hosted in pyrite as less than 10 µm inclusions in the CT. TIMA also revealed that Te minerals exhibited fine-grained liberation of less than 20 μm. Moreover, TIMA results showed that >80% of mica and other silicate minerals were concentrated in size fractions < 38 μm, suggesting that desliming processes would positively impact Te enrichment. The results from the processing tests showed a Te recovery rate of ~77% and a Te enrichment ratio of 13 when using the combination of gravity separation and froth flotation at 90 g/t xanthate collector and 50 g/t glycol frother. The findings from this study show a significant potential for Te recovery from unconventional sources if appropriate physical beneficiation approaches are adopted.

Timing of the deformation in the Gondwanide orogeny: A structural and geochemical shift from syn- to post-tectonic magmatism recorded in the Permian Mamil Choique granitoids, Patagonia

The Sierra de Mamil Choique calc-alkaline granite batholith, covering an area of 320 km2, serves as the key reference for Late Paleozoic magmatism in central-west Patagonia. It comprises I-type weakly to mildly peraluminous tonalites to granites (59.6–75.7%SiO2) displaying various deformational features. This paper presents a micro- and mesostructural study alongside temperature-pressure (T-P) constraints coupled with U-Pb zircon crystallization ages, as well as Ar-Ar and K-Ar mica ages, and mineral and whole-rock geochemistry. The older units (288 ± 1 Ma Cerro Mojón Monzogranite and 281 ± 2 Ma Huenchuquil Granodiorite), exhibit syn-kinematic banding and strong NW-SE foliation showing a transition from magmatic-sub magmatic to high-T subsolidus deformational features, such as parallel alignment of magmatic minerals, sub magmatic fractures, melt pockets, and chessboard subgrains in quartz. Quartz recrystallization by grain boundary migration is also observed. These microstructures developed concurrently with the regional D3 event that affected the Devonian metamorphic host. Their crystallization started at 8 Kbar and ∼ 790 °C within a thickened crust (LaN/YbN = 13–15, average). In contrast, the younger units (278 ± 2 Ma; Nahuelfil and Antinao Monzogranites) exhibit mainly magmatic deformation and display a NE-SW parallel alignment of mostly subhedral K-feldspar. A D4 deformation younger than 278 Ma, with a sigma 1 NW-SE (in plain view- horizontal) would have controlled the emplacement of Nahuelfil and Antinao Monzogranites. Younger zircon ages (ca 265 Ma) in the 278 Ma monzogranites would result from resetting due to the magmatic-hydrothermal alteration associated with the later magmatic pulse of leucogranites and pegmatites of the 267 ± 8 Ma (Rb-Sr WR isochron) La Pintada Leucogranites. These leucogranites were emplaced in an already thinner crust (LaN/YbN = 2.6 average). The latest magmatic activity is represented by two groups of pegmatitic bodies one from 265 ± 6 to 257 ± 3 Ma and a younger one of ca. 252–251 Ma (Ar-Ar and K-Ar muscovite cooling ages). All units share a common mafic source, but the younger units crystallized from melts at lower pressure and temperature (748–725 °C). The magmatism, involving crustal recycling, occurred at an active margin during a stage of thickened crust from 290 to 280 Ma, followed by gradual thinning after 280 Ma. This change in crustal thickness fits models proposing a continuous Permian subduction with a variable dip angle of the subducted slab along the southwestern margin of Gondwana.

استخدام المجهر الألكتروني الماسح في تشخيص المعادن الطينية في بعض ترب الرز العراقية

The Middle Euphrates region, represented by the governorates of Diwaniyah and Al-Najaf, was chosen to conduct the current study. As the two governorates are famous for cultivating various varieties of rice crop. Two methods using to irrigated these soils during the growing season, and called locally wet and dry methods. The morphological features of clay minerals were studied using scanning electron microscope (SEM), to describe the changes that occurred to the mineralogical features of these minerals due to the influence of the irrigation patterns used during irrigation of these soils. The scanning electron microscope (SEM) results show that were many changes in morphological features occurs such as in size and shape of clay minerals, in particular to smectite minerals. The scanning electron microscope (SEM) figure of clays in Al-Najaf(dry) soil showed some of particles appeared as well-formed imperfect hexagonal shape, which revealed that these particles belong to the chlorite mineral. While the mica minerals were appeared in lath-shaped, and rounded flakes in clays of all studied soils. Whereas the montmorillonite particles appear as a thin, webby crust, and have a flat, perming morphology. The variation in the size of the montmorillonite particles was adopted as a basis for the occurrence of the Mg-hydroxide layer within the interlayers of montmorillonite.

Physico-chemical, technological and radiological characteristics of kaolinized granite from northwestern Serbia

In the ceramic industry, the quality of the final ceramic tile as well as the possibility of its use depends on the quality and characteristics of the starting raw materials. One of the potential raw materials that can be used in the production of ceramic tiles is kaolinized granite, and it is necessary to examine its characteristics. In this research, the kaolinized granite of the Jadar block, northwestern Serbia, from the Beli Majdan surface mine, Jadranska Lešnica, was examined. Chemical analysis, X-ray diffraction analysis (XRD), and differential thermal analysis (DTA) were carried out. Ignition tests of the prepared composites were also conducted at three selected temperatures (1000, 1100, and 1250 °C), where total linear shrinkage and water absorption were determined. The activity concentrations of natural radionuclides and the artificial radionuclide 137Cs were determined using the gamma spectrometry method, and then the radiation risk for the external exposure of workers when working with this raw material was assessed. For the samples with the highest content of 226Ra, radon exhalation measurements were performed with the RAD7 device, and the values of the radon emanation coefficient were determined, as well as the values of alpha dose equivalents, which quantified the potential internal exposure of workers. The results of the chemical analysis showed that the content of Al2O3 in the examined composites ranged from 19.11 to 21.00%, and the content of Fe2O3 from 1.53 to 1.72%. Additionally, the K2O content in the tested composites ranges from 4.01 to 5.46%, which indicates the presence of K-feldspar and muscovite, and the Na2O content from 1.82 to 2.61%. Based on XRD analysis, it was established that the mineral composition of kaolinized granite includes quartz, feldspar, mica, calcite/dolomite, and kaolinite minerals. DTA analysis indicates the occurrence of minor endothermic processes at 488.05 °C and 558.12 °C, as well as an exothermic process at 980.8 °C. The color of the ignition is brick red to dark brown red. A trend of increasing linear shrinkage and decreasing water absorption with increasing ignition temperature was observed with the normal appearance of the samples. The average activity concentration of natural radionuclides are around and below the average values for building materials, expect for 40K. The values for 137Cs are below the values measured in soil. Annual effective doses estimated for external exposure are below 1 mSv y−1, which indicates that there is no increased radiation risk when working with this raw material. The values of the radon mass exhalation rate are in the range of 61–113 mBq kg−1 h−1, and the values of the radon emanation coefficient are 6.3–8.4%. The average value of the alpha dose equivalent is 1mSvy−1, which indicates a potential exposure to radon below 100 Bq m−3. Based on the obtained results, it can be concluded that kaolinized granite is a high-quality and radiologically safe raw material for making ceramic composites in the production of ceramic tiles. It has all the necessary characteristics to partially or completely replace feldspar in ceramic composites.

Analytical Study of Polychrome Clay Sculptures in the Five-Dragon Taoist Palace of Wudang, China

During the Ming Dynasty, the Five-Dragon Palace functioned as a royal Taoist temple set atop one of China’s holiest Taoist mountains, Wudang Mountain. Two tower polychrome sculptures with exquisite craftsmanship have remained over the centuries. In this study, the painting materials and the techniques used to construct these sculptures were analyzed through multiple characterization methods, including optical microscope (OM) observations, micro-Raman spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), X-ray diffraction (XRD), micro-Fourier-transform infrared spectroscopy (μ−FTIR), and pyrolysis–gas chromatography/mass spectrometry (Py−GC/MS). The results revealed that the pigments used in these sculptures included red pigments, which were composed of mercury (II) sulfide (cinnabar or vermillion), minium (Pb3O4), and hematite (Fe2O3); green pigments, which included atacamite and botallackite (Cu2Cl(OH)3), and blue pigments, which comprised smalt (CoO·nSiO2) and azurite (Cu3(CO3)2(OH)2). The white base layer was composed of quartz and mica minerals combined with gypsum or plant fiber, and the gold foil was adhered to the surface using heated tung oil. In addition, a special multi−layer technique was applied, with red under the golden gilding, white under the blue layer, and gray and black under the green layer. Drying oil was used as a binder for lead-containing pigments. This study offers substantial proof of reliable techniques to use in the continuing conservation of these sculptures, and it also serves as a foundation to determine if they can be dated to the late Ming or early Qing Dynasty (17th century).

Exploration of Quartz, Feldspar, and Mica Minerals Using Geophysical Resistivity, Self-Potential, and Natural Electrical Field Techniques

The aim of the present study is examined by various modeling and self-potential (SP) techniques which are useful for the exploitation of shallow and deep deposits. In the present study area, 12 areas conducted the self-potential techniques. From that analysis, a v-shaped formation was formed, as may be the geological formation of an ore anomaly. The study area's highest millivolt values (30 to 50 mV) indicate the presence of quartz, feldspar, and negative values are associated with the mica group of minerals. The Nellore schist belt is majorly dominated by the schistose group of rocks. The schistose group of rocks has a density very less like 5 to 10 MV. This study would be helpful for various arenas, including exploration geologists and mineralogists.

Processing of gypsum-bearing materials in the bronze age Gonur Depe archeological site (Southeast Karakum Desert)

The technology of preparation of an ancient binder mixture used in construction work at the Gonur Depe archeological site (Southeast Karakum desert) is interpreted on the basis of study of its mineral composition and textural-structural features. The material is composed of thin prismatic-angular and fbrous aggregates of reduced gypsum (60–70 %) and β-bassanite (3 %) enclosed in clay-siliceous matrix (20–30 %). The mixture also contains grains of quartz (5–10 %), feldspar (up to 1%), mica (up to 1 %) and other minerals. The mixture was produced from a crushed natural gypsum stone, which was calcinated in air. In this case, gypsum is converted to β-bassanite and partly to anhydride. The morphology and sizes of mineral particle confrm the presence of the calcination stage up to 200 °C. The further addition of water to a dry mixture caused rapid thickening and cementation of the material, which could be used for whitewashing and plastering of the walls.

Process Mineralogy of Lithium and Rubidium in the Diantan Polymetallic Mining Area, Tengchong, Southwest China

Highly differentiated granite often contains abundant key metal resources, such as lithium and rubidium. The Tengchong area of Yunnan hosts a large number of highly differentiated granites from the Cretaceous age. Among these, granite samples from the Diantan tin–lead–zinc polymetallic mining area exhibit Li contents exceeding 0.02% and Rb contents surpassing 0.1%. This suggests a promising potential for Li and Rb mineralization. However, the occurrence status and process mineralogical characteristics of Li and Rb remain unclear, directly impacting the assessment of the region’s comprehensive utilization potential for these key metals. This study focuses on representative granite samples from the Diantan mining area to conduct petrographic and process mineralogical research, examining single mineral chemical composition, physical properties, element occurrence state, and mineral embedding particle size. The results indicate that mica minerals primarily contain Li, while both feldspar and mica minerals are the main carriers of Rb. Zinnwaldite not only contains the highest Rb proportion among the samples but also plays a significant role in Li occurrence. Based on the dissociation characteristics, it is recommended to grind the material to a fineness of −0.075 mm, comprising 80% of the particles, before proceeding to the final flotation process. This would result in approximately 95% dissociation of the mica in the sample. Since mica is predominantly distributed between quartz and feldspar particles, with relatively low binding force, it facilitates mineral dissociation during the grinding process. Therefore, the actual beneficiation process may consider a moderately coarser grinding fineness based on the aforementioned findings.

Impact of soft minerals on crack propagation in crystalline rocks under uniaxial compression: A grain‐based numerical investigation

AbstractVarying external conditions in the metallogenetic process of crystalline rocks contribute to the complex mineral and textural characteristics, rendering the mechanical properties highly heterogeneous at the mineral scale. This research focused on the influences of minerals with relatively low strength and stiffness (soft minerals) in crystalline rocks on their cracking behavior. A particle‐based discrete element method (DEM) was first employed to establish random grain‐based models (GBM) of crystalline rocks containing soft minerals with different contents, strengths, and stiffnesses. On this basis, responses of the mechanical properties and crack propagation to these parameters were systematically investigated and an optimized micro‐parameter calibration method for real CT (computed‐tomography) ‐based GBM was then proposed considering the characteristics of soft minerals. The results demonstrate that with the decrease of the strength of soft mica, the intragranular cracks are prone to initiate and propagate inside the soft minerals and lead to the final crack coalescence. The decrease in the stiffness of soft minerals enhances their controlling effects on the cracking propagation. Based on the CT‐based granite model, it was found that a heterogeneous stress field is produced due to the spatial distribution of the soft (mica) and hard (quartz and feldspar) minerals, and the mica minerals tend to terminate cracks or force cracks to deflect or bypass individual grains during crack propagation. This study sheds light on the damage and failure processes of crystalline rocks with contrast mineral components.

Gold-bearing quartz veins and associated rocks in the Wawa area, western Nigeria: Insights to their nature from field investigation, petrographic study, and geochemical analysis

This study focused on the Wawa area, a southern extension of the Zuru Schist Belt (ZSB) in Northwestern Nigeria. The ZSB is one of western Nigeria's broadest and least studied schist belts. Information about its full extent, petrological, and geochemical characteristics still needs to be improved. Preliminary field investigations have shown that the Wawa study area possibly hosts orogenic gold deposits. This study carried out field investigation, petrological study, and geochemical analysis to understand and characterize the tectonic setting and possible origin of gold mineralization in the area. In total, 40 rock samples were studied under the microscope and 72 samples were subjected to geochemical analysis, including X-ray fluorescence (for major and trace elements) and X-ray diffraction analyses. The field investigation revealed that the rocks in the area are mainly gneiss, migmatite, amphibolitic rocks, phyllites, granitoids, and intrusive rocks such as quartz veins and pegmatite veins. Gold mineralization is confined to the quartz veins in amphibolitic rocks, and micro veins of pyrite and chalcopyrite are apparent in the amphibolitic rocks as well. The petrological and mineralogical studies showed that quartz is dominant in the samples from the Wawa study area, together with feldspars, mica, and other accessory minerals. The XRF data showed that the rocks underlying the Wawa study area are highly enriched in silica; meanwhile, several trace elements exist in anomalous concentrations compared to the corresponding average elemental values in the upper continental crust and based on several other reports from western Nigeria. The underlying rocks in the study area are mostly peraluminous with few plotting as peralkaline. Gneisses in the area are orthogneisses. The amphibolitic rocks in the area show both tholeiitic and calc–alkaline affinity. The K2O/Al2O3 vs Na2O/Al2O3 discrimination plot suggested that gold-bearing fluids in the area are likely from igneous and sedimentary sources. Despite the new data/information contributed by this study, further geochemical studies within the ZSB are required to fully understand the evolution and origin of gold mineralization in the area.

Whole-Rock Geochemistry and Mica Compositions in Lijiagou Pegmatite Spodumene Deposit, Western Sichuan, China

The Lijiagou pegmatite spodumene deposit, located in the middle of the Songpan–Garze Fold Belt and southeast of the Ke’eryin ore field, is a newly discovered super-large deposit. In order to reveal the metallogenic tectonic environment and evolution process of pegmatite, based on the study of the geological characteristics of pegmatite, we carried out a whole-rock geochemical analysis of Ke’eryin two-mica granite and Lijiagou pegmatite and carried out a detailed electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis of mica minerals in each zonal pegmatite. The results show that the Ke’eryin two-mica granite is mainly formed in the transition period from syn-collision to post-collision. After the end of the continental collision, the crust is squeezed and thickened in the post-collision extensional transition tectonic environment. Mica from the microcline pegmatite zone (MP) to the albite spodumene pegmatite zone (ASP) in pegmatite show different compositions and structural characteristics, with the evolution trend in the direction from muscovite to Li-bearing mica. The type of mica from MP to AP is mainly muscovite, and Li-bearing mica appears in ASP, which is secondary and metasomatic at the edge of primary muscovite. From MP to ASP, there was a negative correlation between Nb/Ta, K/Rb and the Li, Rb, and Cs contents of mica, while the contents of Li, Rb, Cs, and F in the Li-bearing mica of ASP increased sharply. This evidence illustrates that the favorable tectonic environment contributed to the formation of the Lijiagou pegmatitic spodumene deposit. Lijiagou pegmatite experienced the magmatic–hydrothermal evolution process and has a high degree of differentiation and evolution from MP to ASP, which gradually increased. Combined with the change in mica type, it is considered that ASP formed from the stage of magmatic transition to hydrothermal and was a hydrothermal environment, and Li, Rb, and Cs mainly began to enrich at the stage of magmatic–hydrothermal transition.