Abstract:X-ray powder diffraction, infrared spectroscopy, electron microprobe, laser ablation inductively coupled plasma mass spectrometry and ultraviolet-visible spectrophotometer were used to test and analyze the phase composition and color genesis of different shades of pink opal samples from Peru. The results show that the main mineral composition of pink opal is Opal-CT, palygorskite, quartz and water, and the type of water is rich, including crystal water, structural water and zeolite water. Combined with X-ray powder diffraction, electron microprobeand infrared spectrum analysis, it is considered that the color of pink opal is related to palygorskite, and the content of palygorskite was quantitatively analyzed by XRD, which was positively correlated with color. UV-visible spectrophotometer combined with electron microprobe and laser ablation inductively coupled plasma mass spectrometry showed that the color of pink opal was related to the organic quinones, β-carotene and Mn²⁺, and the more the content of Mn²⁺, the darker the color. At the same time, the effect of Fe³⁺ on color was proposed, and it was found that Fe³⁺ only appeared in dark samples.

Abstract:The natural Tanzanian zoisite (tanzanite), with its distinctive blue-violet tone, is a rare and valuable gemstone. Heat treatment can optimise the color of zoisite and make it more economically valuable. However, the exact cause of this captivating blue-violet of zoisite has been a subject of debate for years. This study presents an examination of natural yellow and blue zoisites. The color changes of stones at different thermal stages were observed by setting three different temperature conditions 300℃, 400℃ and 500℃, and using the L^*a^*b^* color parameter. The research findings indicate that the gemological properties of different colored zoisites remain consistent before heat treatment. It was determined that a temperature of approximately 500℃ is optimal for achieving a light blue-violet tone in zoisite. Heat treatment results in a pronounced enhancement of the blue-violet hues, enabling the modulation of zoisites’ yellow or brown undertones through temperature control. Notably, the yellow zoisite experiences a fascinating color transformation from yellow-brown to blue-violet, with the critical temperature range between 400℃ and 500℃. Using energy dispersive X-Ray spectroscopy (EDXRF), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and ultraviolet and visible spectrophotometry (UV-VIS) techniques, the study identified that the blue color in natural zoisite is primarily caused by V³⁺ and Ti³⁺ ions working in tandem. On the other hand, the yellow color is mainly attributed to Ti³⁺. The V/Ti ratio plays a supporting role in coloration of natural zoisite. Moreover, the development and intensification of blue-violet tones in heat-treated zoisite, as well as the transition from yellow to blue-violet, are intricately linked to the charge migration of Ti³⁺+V⁴⁺→Ti⁴⁺+V³⁺.

Abstract:Photochromism is the most significant and valuable optical characteristic in hackmanite. EDXRF, FTIR, UV-VIS-NIR, D65 standard light source, illuminator and colorimetry method were applied in this paper to study the decolortation efficiency of photochromism in hackmanite from Mogok, Myanmar (Burma). The results indicated that the major elements of hackmanite are Na, Al, Si, O, Cl and S, its trace elements should include Ca, K and Fe. There are three absorption peaks of 472, 540 and 667 nm in UV-VIS-NIR spectrum, with 540 nm having the strongest absorption peak. The peaks stay stable but their intensity decrease with time during decoloration. The absorption peak area of 540 nm is significantly negative corelated with time during 0～80 s (R²=0.99). The decoloration efficiency grows significantly when the luminance increases from 5 000 lx to 30 000lx. During decoloration, the lightness of hackmanite color increases, while its chroma decreases. The color parameter a^* decreases and b^* increase. Its hue turns from purple to pink slightly. All the color effect of photochromism in hackmanite is a direct result of charge transfer leading to the destruction of the F center in hackmanite.

Abstract:Emerald is a precious colored gemstone, and its origin has a significant impact on the evaluation of its value. The identification of the origin of emerald has become an important technology in gemstone laboratories and a research hotspot in the field of gemology. The inclusion, spectral characteristics, and chemical composition of emerald are commonly used and critical information for origin determination. However, with the accumulation of research data on the origin of emerald, traditional methods for origin determination are facing challenges. This article systematically summarizes and analyzes the gemological characteristics, inclusion information, spectral features, and major and trace element data of emeralds from various occurrences around the world. Based on a review of previous research results, it systematically elucidates the current research status of emerald origin determination, summarizes the gemological characteristics and inclusion characteristics, reveals the component fingerprint of emeralds from each occurrence, and uses case studies to illustrate the methods of distinguishing common and important origins of emeralds. Although the comparison at a global scale indicates that the inclusion varieties of emerald from different origins are mostly similar, with spectral convergence and significant overlap in component content ranges, novel approaches for origin determination are proposed based on inclusion frequency, UV-VIS-NIR spectral patterns, absorption patterns of HDO and D₂O, and the parameter selection of compositional diagrams.

Abstract:As one of the four famous inkstones in China, She inkstone has high economic and artistic value. She inkstone samples were collected in Wuyuan, Jiangxi Province. To explore the causes of the unique texture of She inkstone, and the mechanism of ink generation in She inkstone, this paper has observed and tested samples under optical microscope, environmental scanning electron microscope (ESEM), energy dispersive spectroscopy (EDS) and electron microprobe (EMPA). The results have indicated that the main minerals of She inkstone include sericite, quartz and chlorite. It has also found that the She inkstone’s different texture is controlled by the degree of metamorphism of primary minerals and the stress deformation of original rock. Combining its microscopic structure and inkstone edge mechanism, quartz provides coarse grinding, sericite and chlorite provide fine grinding during the ink-making process. By calculating the density of She inkstone’s edges, this paper argued that She inkstone is belong to high-density group, and quantitatively evaluated the practical properties of She inkstone from a numerical perspective. Combined with self-sharpening edge mechanism, this paper explains why She inkstone can maintain excellent ink-making performance for a long time. In comparison with other inkstones, She inkstone shows outstanding advantages in both ornamental and practical aspects.

Abstract:Aquamarine belongs to the beryl group minerals and is produced in granite pegmatites. Its crystallization process can run through different stages of the evolution of pegmatitic magma, and it is also an important host mineral for magma melts and fluid inclusions. Kujierte pegmatite is an LCT type pegmatite that can produce high-quality aquamarine among numerous pegmatite veins in the Koktokay area of Altay, Xinjiang. This article investigates the main, trace elements, and fluid inclusions of aquamarine produced in Kujierte pegmatite. Fluid inclusion petrology shows that the distribution of melt/melt fluid inclusions (MI/M-FI) and fluid inclusions (FI) in aquamarine exhibits a certain pattern: MI/M-FIs are mainly concentrated from the root to the middle of the crystal, while FIs are enriched in the edge region, indicating that the crystallization process of the aquamarine has undergone a relatively complete stage of pegmatite magmatic evolution. The temperature measurement results show that the homoge-nization temperature of M-FIs is >550℃, and the homogenization temperature range of FIs is 220~400℃, with salinity ranging from 0 to 14% and density ranging from 0.6 to 0.9 g/cm². The fluid belongs to H₂O-NaCl-CO₂ system with the medium high temperature and medium low salinity. Based on the orientation of crystal crystallization and the distribution of fluid inclusions, the magma hydrothermal transition stage and post magmatic hydrothermal stage were divided. Electron probe analysis (EPMA) and laser ablation plasma mass spectrometry (LA-ICP-MS) analysis results showed that Fe element dominated the coloration of aquamarine. During the growth process of aquamarine, Fe²⁺ entered the mineral lattice in a channel octahedral substitution mode of Na⁺+Fe²⁺→ Al³⁺, resulting in a light blue coloration. In the early to middle stages of the evolution of pegmatites, the content of alkali metals (Li, Na, K, Cs) and transition metal (Fe, Mg, Mn) elements in aquamarine remained stable, and in the late stage, the content of these metal elements increased sharply. Combined with the long-term compression and subduction of plate in the region, which has led to the overflow of deep material in the earth, and the evolution of pegmatite magma in an unclosed system, it is believed that the fluid enriched with Fe, Mg, and Mn in the deep magma chamber was injected in a pulsating manner in the late stage, resulting in a fluctuating change in the composition of the original hydrothermal fluid.

Abstract:In order to improve the screening efficiency and accuracy of batch small particle diamonds, this paper developed a new type of ultraviolet photoluminescence image high-speed acquisition device—jewelry observation and identification instrument (DDO). Through the selection of excitation light source, industrial camera, structural design technology breakthroughs, and innovation in the collection method of luminescence phenomena, it achieved batch observation of photoluminescence phenomena and luminescence delay differences between different gemstones, thereby achieving efficient detection of gemstones. The DDO test results on over 20000 colorless natural diamonds, synthetic diamonds, and imitation diamonds show that 98% to 99% of colorless natural diamonds exhibit a blue phosphorescence phenomenon within 0.1~10 ms after the cessation of ultraviolet light excitation, which is a typical feature of natural diamonds. The luminescence characteristics (luminescence color, intensity, duration, structural zoning) of synthetic diamonds and other colorless gemstones are significantly different from natural diamonds. Therefore, a new method for rapid and accurate screening of colorless natural diamonds is established by observing the differences in continuous luminescence (phosphorescence) characteristics, including fluorescence and decay time within 100 ms, as screening conditions. This device improves the accuracy and detection efficiency of diamond identification, with a screening pass rate of up to 99% for natural diamonds and 100% for synthetic and imitation diamonds.

Abstract:This study conducted corrosion experiments on different types of pearls, including heating, ultraviolet radiation, sweat, shower gel, and sunscreen, to analyze the effects of these corrosion methods on the color and chemical composition of pearls. The results show that heating has the least impact on the decrease of pearl color, while sunscreen and shower gel have the greatest corrosion effect. Gold pearls exhibit the most significant decrease in color under various corrosion methods. In the chemical composition analysis of pearls before and after corrosion, it was found that various corrosion methods generally led to an increase in Ca content and a significant decrease in Si content on the surface of pearls. The content changes of Mn and Sr are related to the type of pearl and the corrosion method. Exploring the effects of different external conditions on the color changes of pearls can provide reference for museum exhibitions and consumer purchases.

Abstract:This study comprehensively analyzed the basic gemological characteristics, X-ray fluorescence spectroscopy (XRF), infrared spectroscopy, Raman spectroscopy, and other aspects of green apophyllite samples with different tones in the Huanggangliang area of Inner Mongolia, and systematically explored the chemical composition and spectral characteristics of green apophyllites samples with different tones. Through high-pressure X-ray diffraction (HPXRD) spectroscopy testing, the crystal structure characteristics of the mineral under high-pressure environment were analyzed in depth, providing key clues for revealing the stable depth of existence of apophyllites after subduction into the crust during geological movement. The research results indicate that the apophyllites in the Huanggangliang area of Inner Mongolia belong to fluorine apophyllites, the content of Fe³⁺ and crystalline water exert a significant influence on the intensity of the green color in apophyllites. In the HPXRD experiment, as the pressure increases, the axial length and cell volume of apophyllites gradually decrease, especially the compression rate of the c-axis is higher than that of the a-axis. At the pressure nodes of 9.0 GPa and 15.3 GPa, a sudden change in compression rate was observed, accompanied by the emergence of new diffraction peaks and the splitting and disappearance of old diffraction peaks. This discovery reveals two distinct phase transitions of apophyllites crystals in high-pressure environments. This study provides strong scientific basis for identifying apophyllites and searching for mineral resources, and also provides a new perspective and understanding for further research on apophyllites in the field of geology.

Abstract:The conventional gemological properties, chemical composition, crystal structure, and inclusions composition and characteristics of the Nigerian gahnite were analyzed in depth by conventional gemological testing, electron probe, single crystal X-ray diffraction, and Raman spectroscopy. The gahnite exhibits well-preserved octahedral crystal morphology, strong vitreous luster, and semi-transparency, with a relative density ranging from 4.48 to 4.61 and a refractive index of 1.792 to 1.794, displaying inert fluorescence under ultraviolet light. The electron probe analysis determined its chemical formula as Zn_(0.87~0.92)Fe_(0.06~0.07)Al_(1.98~2.01)O₄. Single-crystal X-ray diffraction revealed a cubic crystal system with space group Fd3m, lattice parameter a=8.089(2)Å, tetrahedral bond length T—O=1.953(4)Å, and octahedral bond length M—O=1.912 9(19)Å. Characteristic Raman absorption peaks for gahnite were identified at 418 cm^-1 and 659 cm^-1, corresponding to the E_g mode and high-frequency T_2g(3) mode, respectively. Raman spectroscopy of inclusions confirmed the presence of various minerals in gahnite, including sphalerite, albite, muscovite, quartz, beryl, zircon, and phenacite. Combined with previous studies, it is believed that gahnite in Nigeria is formed in granite-pegmatite rich in Li, Cs, Rb, Be and Ta.

Abstract:In recent years, a kind of black cyan nephrite containing pyrite has appeared in the domestic market. It is mainly produced in Xinjiang and belongs to a relatively rare nephrite variety, which has mining and utilization value. This article systematically analyzed the mineralogical and geochemical characteristics of seven samples using conventional gemological instruments, polarized light microscopy, infrared spectroscopy, Raman spectroscopy, X-ray powder diffraction (XRD), electron probe (EPMA) laser inductively coupled plasma mass spectrometry (LA-ICP-MS), and isotope mass spectrometer (MC-ICP-MS). The results show that the color of black cyan nephrite is dark green to black, the refractive index is 1.61, the relative density is 3.08~3.17, and the Mohs hardness is 6.0~6.5. The main component mineral is tremolite, the secondary mineral is mainly pyrite, and a small amount of chlorite, epidote, sphene, zircon, and graphite are also contained, with a typical fiber interlaced structure; The characteristic peaks of infrared and Raman spectra are consistent with the standard peaks of nephrite; The main chemical components of the sample are SiO₂, MgO, CaO and FeO. The Mg/(Mg+Fe²⁺) value indicates that some tremolite has transitioned to actinolite. Based on the trace element Cr-Ni mapping, the sample is identified as a dolomite marble type genesis, while the content of rare earth elements is relatively low, in a left leaning mode, The ore-forming hydrothermal fluid is mainly magmatic water, containing a small amount of metamorphic water. The sample contains pyrite with Co/Ni>1 and small amounts of As, Se, Cu, Zn and Pb, δ³⁴S ranges from 8.87‰ to 20.92‰, suggesting that it is of magmatic-hydrothermal origin and the source of sulfur is a mixture of magma and formation sulfur.

Abstract:55 Myanmar purple jadeite-jades samples were comprehensively analyzed by electron microprobe analysis (EMPA), energy-dispersive X-ray fluorescence (ED-XRF) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy and colorimetric methods. The results show that the main chemical compositions of Myanmar purple jadeite-jades are SiO₂, Al₂O₃ and Na₂O, and the contents are close to those of standard jadeite. Chromaticity test analysis showed that the chroma C^* of purple jadeite-jade is mainly controlled by the colour coordinate a^*, while the hue h° is mainly controlled by the colour coordinate b^*. Myanmar purple jadeite-jades can be classified into two types: Type Ⅰ show the main absorption bands at 570 nm which is assigned by chromophore Mn³⁺ and Type Ⅱ with two main absorptions at 540 nm and 610 nm are colored by charge transfer between Fe²⁺-Ti⁴⁺. The absorption peaks of Fe³⁺ existed in both types of Myanmar purple jadeite-jades, and the full iron content in the samples determined their hue and lightness.

Abstract:The color characteristics, chemical composition and spectroscopic characteristics of the yellow-red Huanglong jade samples from Myanmar were studied through Fourier transform infrared spectrum, laser Raman spectrometer, ultraviolet-visible spectroscopy, an X-ray fluorescence spectrometer, electron microprobe analyzer, and an X-Rite SP62 hand-held spectrophotometer. The quantitative relationship between the color and spectral characteristics of Huanglong jade from Myanmar was analyzed. The results show that yellow-red Huanglong jade from Myanmar is mainly composed of SiO₂, with small amounts of Fe, Cu, Cr and other transition metal elements, and belongs to the cryptocrystalline quartz jade. Under CIE D65 standard light source and N9 Munsell neutral background, there is a high correlation between the lightness and the hue angle of the Huanglong jade from Myanmar, and the change of iron content has a significant effect on the lightness and hue angle of the Huanglong jade from Myanmar. The first derivatives of the ultraviolet-visible absorption spectra can infer the relative contents of goethite and hematite in the Huanglong jade from Myanmar, and the color of the Huanglong jade from Myanmar changes from yellow to red as the position of the primary wave trough shifts toward the long-wave direction.

Abstract:Yellow silicified scleractinia has gained popularity in the market due to its unique pattern and beautiful color. To comprehend the structural characteristics and color origin of silicified scleractinia, three natural yellow silicified scleractinia were studied using X-ray powder diffractometry, polarising microscopy, thermal field emission scanning electron microscopy, UV-visible spectrophotometry, and Raman spectroscopy. There are differences in the morphology, species, and distribution of quartz particles in the space and the septa area of the scleractinia samples. The quartz particles will develop along the inner wall to the center, with irregular fine grain, xenomorphic medium grain, and xenomorphic semidiomorphic coarse grain when the space between the septa and the theca or the coenosteum is sufficiently large. The quartz particles are mainly xenomorphic or fibrous fine quartz when the cavity is compressed. In the septa area, the quartz particles are mainly fine quartz. The yellow and brownish-red minerals in silicified scleractinia observed under a polarizing microscope were confirmed to be goethite and hematite, respectively. Hematite is the main cause of the yellow color in silicified scleractinia. Due to the influence of coral bone structure, goethite and hematite always exist in the space of very fine or fine quartz particles in the microcosmic form of pigment points. They are enriched in the septa area and the margin of space.

Abstract:Yunxiao is a significant producing area of gem-quality garnet in China. However, the color origin of garnet in this area remains ambiguous, which restricts the understanding of their formation mechanism and subsequent exploitation. In this paper, 7 samples of orange-yellow-orange-red garnet from Yunxiao, Fujian were selected, and the spectral characteristics of the samples were analyzed by Fourier infrared spectrum, UV-visible spectrum and Raman spectrum, and the characteristics of main and trace elements were defined by electron probe (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. It is concluded that the color of the garnet is predominantly influenced by the absorption of visible light by Mn²⁺ and Fe²⁺. Mn²⁺ dictates the yellow tone of the garnet, while a minor amount of Fe²⁺ governs the orange-red tone. Additionally, a trace amount of Ti⁴⁺ imparts a brownish appearance to the garnet. The samples exhibited a relatively low manganese content and high iron and magnesium content in their core, a gradual increase in manganese content from the core to the rim. The samples also displayed a left-leaning partition pattern, with an enrichment of heavy rare earth elements and a deficit of light rare earth elements. Europium (Eu) showed a negative anomaly. These findings suggest that the garnets from Yunxiao, Fujian were formed during magmatic processes and are products of late-stage magmatic crystallization.

Abstract:The Brazilian diamond samples were analyzed by conventional gemological testing instruments combined with Fourier transform infrared spectrometers (FTIR), laser Raman spectroscopy, and Diamond View^TM. The results revealed that the surface microforms of Brazilian diamonds are extremely diverse, featuring various growth mounds, trigonal, hexagonal, or irregular fusion pits, as well as plastic deformation slip lines. The Brazilian diamond samples are predominantly composed of the ⅠaAB type, accounting for over 90% of the total samples. It exhibits a nitrogen content ranging from 400×10^-6~1 700×10^-6 and a B core conversion rate between 15% and 66%. These findings indicate that Brazilian diamond samples are characterized by a high nitrogen content and a low to moderate degree of nitrogen aggregation. Raman spectroscopy analysis shows that there is residual compressive stress or poor crystallinity inside the sample. Diamond View^TM luminescence images reveal blue and yellow-green fluorescence is popular in Brazilian ⅠaAB diamonds. Type ⅠaB diamonds exhibit blue fluorescence with green hues and an uneven blue fluorescence. The Type Ⅱa diamond samples exhibit dark orange and blue fluorescence.

Abstract:Henan Miyu jade is an important variety of jade in China, which belongs to the phanerocrystalline quartzite. A systematic geological study of the Miyu jade deposit in Xinmi City, Henan Province, has been carried out, but its gemmological characteristics and color genesis remain controversial. This paper synthesizes the research results of the previous researchers, and obtains the gemological characteristics, spectroscopic research characteristics and chemical composition characteristics of the green series of Henan Miyu jade samples by routine gemological testing, FTIR spectroscopy, UV-VIs spectroscopy, Raman testing and electron microprobe testing. The results show that Miyu jade is a quartzite with good crystallinity. The main mineral component is α-quartz, and minor minerals include muscovite, hematite, carbonaceous minerals, rutile, tourmaline, etc. It has a granular metamorphic structure and a microscopic fine-grained metamorphic structure. Significant characteristic absorption peaks of Cr³⁺ were seen in the UV-visible spectrum. The green color of Miyu jade is related to chromium-containing white mica, and the green color of chromium-containing white mica is caused by the trace elements it contains, such as Cr, V, Ni and other color-causing elements. The darker the green color, the higher the content of Cr, Ni and V. With the increase of Fe³⁺ content, the yellow tone of the sample is more obvious.

Abstract:This paper presents a comparative study of the spectral characteristics of copal resins from six different origins: Russia, New Zealand, Borneo, Madagascar, Colombia, and Sumatra. The study uses gemstone microscopy, infrared spectroscopy, ultraviolet fluorescence observation, and three-dimensional fluorescence spectroscopy to identify the characteristics of the resins. The results indicate that the infrared spectra of Borneo and Sumatra copal resins are mainly characterized by four absorption peaks in the range of 3000~2800 cm^-1, absorption peaks at 1708 cm^-1 and a shoulder peak at 1732 cm^-1, a weak absorption peak at 888 cm^-1. Similarly, the main features of the infrared spectra of New Zealand copal resin are three absorption peaks in the range of 3000~2800 cm^-1 and weak absorption peaks at 1 642 and 888 cm^-1. The infrared spectra of copal resins from Madagascar, Colombia, and Russia exhibit similarities, with three combined characteristic absorption peaks associated with C=C, a strong absorption peak at 1 692 cm^-1, and two absorption peaks of comparable intensity at 1270 and 1180 cm^-1. Under long-wave UV fluorescence, the fluorescence intensity of Borneo and New Zealand copal is stronger than that of resins from other origins, but the fluorescence intensity of Borneo copal is significantly stronger and the fluorescence intensity of Madagascar copal is the weakest. Borneo and Sumatra copal resins emit three typical peaks at 445, 474 and 505 nm, which can be optimally excited by 416,447 nm. The strongest emission peak of New Zealand copal is at 385 nm, which can be best excited by 352 nm. The strongest emission peak of Russian copal is at 399 nm, which can be best excited by 354 nm. The strongest emission peak of Colombian copal is centered at 470 nm, which can be best excited by 400 nm; and the relative fluorescence intensity of Madagascar copal is the weakest, the strongest fluorescence peak is at 465 nm, which can be best excited by 378 nm. It was concluded that the fluorescence and infrared spectroscopic characteristics of the copal resin could provide a basis for the identification and classification of the resin.

Abstract:The North China Craton (NCC) has undergone a long and complicated geological process. During the Mesozoic, a series of intermediate-acid granitoids were formed in the Taihang Mountains. Mapeng granitic pluton is located in the northern part of Taihang Mountains, emplaced in Fuping complex, with porphyritic monzonitic granite, granodiorite and quartz diorite exposed from the center to the edge. The petrology, petrochemistry, genetic type of Mapeng granitic pluton have been studied by predecessors, but the type and source of granitic pluton are still controversial. In this paper, the petrochemistry, zircon SHRIMP U-Pb isotopic chronology and Lu-Hf isotopic composition of porphyritic monzonitic granite, granodiorite and quartz diorite in Mapeng pluton are systematically studied, and the geochemical type, formation age and magma source nature of Mapeng granite are further discussed. Geochemical magmas show that the Mapeng granite has high SiO₂、Na₂O+K₂O、Ba、Sr、LREE and the ratio of K₂O/Na₂O, lower Al₂O₃、MgO、Rb、Nb、Ta、Th、U、Y、HREE and Mg^#value, no obvious Eu anomaly and obvious depletion of high field strength elements such as Nb, Ta, P and Ti. The SHRIMP U-Pb isotopic ages of the three newly obtained granites with different facies belts are 129.4±1.4 Ma, 131.2±2.2 Ma, 129.5±1.3 Ma, and they have similar major element compositions and REE and trace element distribution patterns. It also reflects that the Mapeng pluton is a magmatic activity of the same period, and has undergone rapid emplacement and cooling crystallization. Lu-Hf isotopic analysis shows that the εHf(t) value of magmatic zircon from the Mapeng granite is -27.00~-15.44, and the two-stage model age t_DM2 is 2 358~1 765 Ma. The magma source of the Mapeng granite is the result of mixing of mantle magma and magma formed by partial melting of Precambrian metamorphic basement.

Abstract:The Changzhougou Formation is one of the oldest sedimentary cover on the Archean-Paleoproterozoic metamorphic basement of the North China Craton. The analysis for the U-Pb geochronology and Hf isotopes of the detrital zircons from the Changzhougou Formation is of great significance for exploring the formation age and source characteristics of the Changcheng System as well as the basement evolution. In this study, LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) and LA-MC-ICP-MS (laser ablation multiple inductively coupled plasma mass spectrometry) were employed to analyze detrital zircon U-Pb ages and rare earth element composi-tions and Lu-Hf isotopic compositions of samples from the Changzhougou Formation of the Changcheng System in the Wengcheng area, Zanhuang Complex, respectively. The main peak ages of detrital zircons in two sandstone samples is 2 500 Ma, and the detrital material of the quartz sandstones is mainly derived from the late Neoarchean metamorphic basement in the North China Craton, and the ²⁰⁷Pb/²⁰⁶Pb age of youngest detrital zircon is 1 822 Ma, combining with the 1850 ~ 1800 Ma metamorphic ages which was recorded by the Zanhuang metamorphic basement and the 1635 Ma age of magmatic zircon from the volcanic rocks in the upper Dahongyu Formation, further define that the initial depositional timing of Changzhougou Formation of Changcheng System in the Zanhuang Complex is later than 1800 ~ 1635 Ma. The εHf(t) values of the detrital zircon from one quartz sandstone sample vary from -6.8 to +5.2, and the corresponding two-stage model peak age is 2 820 Ma. Combined with the published Hf isotope results of 2900 ~ 2700 Ma magmatic zircons and detrital zircons from the Zanhuang Complex, it is further indicated that 2900 ~ 2700 Ma is the most important period of crustal growth in the Zanhuang Complex. Integrating with the published sedimentary and new geochronological data of the Changzhougou Formation of the central and southern parts of the Taihangshan area, it is speculated that the Changzhougou Formation in Wengcheng area was deposited in the continental rift basin.

Abstract:As one of the important antimony mining areas in China, a large number of antimony polymetallic deposits (points) have been discovered in the southern Hubei antimony mining area. With the depletion of shallow antimony ore resources, there has been no new progress in the exploration of middle and deep parts. Therefore, there is an urgent need to find a fast and effective exploration method, conduct in-depth research on the exploration model and prediction of the area, in order to expand the amount of resources and exploration results. This article takes the Jinyinshan antimony polymetallic deposit as the research object. Short wave infrared spectroscopy (SWIR) technology was used to scan the rock cores of ZK3101 and ZK2701 boreholes in Jinyinshan antimony deposit, obtaining information on the types, combinations, and spectral parameters of altered minerals in Jinyinshan antimony deposit. The altered mineral zoning was divided, and the relationship between mineralization and altered mineral zoning was analyzed. The main altered minerals in the Jinyinshan antimony gold deposit include mica, chlorite, carbonate, etc. Among them, the sericite mineralization zone is closely related to mineralization. By calculating the Al—OH spectral characteristic parameters of sericite minerals, it was found that the crystallinity (IC value) of sericite at the mineralized site and the absorption peak value (Pos 2200) of the Al—OH 2200 nm characteristic peak showed low value anomalies (IC<2, Pos 2200<2205 nm), which can be used as an effective indicator of mineralization. It is believed that the application of shortwave infrared spectroscopy technology can quickly delineate antimony gold deposits, effectively guide mineral exploration, reduce exploration costs, improve exploration efficiency, and achieve breakthroughs in mineral exploration.