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Article

The Short-Wave Infrared (SWIR) Spectral Exploration Identification and Indicative Significance of the Yixingzhai Gold Deposit, Shanxi Province

by
Lifang Wang
1,
Song Wu
1,*,
Xiaodan Lai
2,
Weili Yang
2,
Rongliang Sun
3,
Peng Liu
1,
Yandong Yang
1 and
Yuxin Ren
1
1
School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
2
Zijin Mining Group Co., Ltd., Longyan 364200, China
3
Shanxi Zijin Mining Co., Ltd., Taiyuan 034302, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(1), 83; https://doi.org/10.3390/min15010083
Submission received: 28 November 2024 / Revised: 10 January 2025 / Accepted: 14 January 2025 / Published: 16 January 2025
(This article belongs to the Special Issue New Discovery and Exploration Methods of Porphyry and Epithermal Mineral Deposits)
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Abstract

:
The Yixingzhai gold deposit is the largest gold deposit in Shanxi Province and develops three types of mineralization: porphyry, quartz vein, and breccia. Spectral characteristic parameters of muscovite are studied by short-wave infrared (SWIR) spectral, and the exploration significance is discussed. The Al-OH wavelength of muscovite associated with porphyry mineralization gradually becomes shorter from the periphery (>2206 nm) to the center (2201–2205 nm), and the crystallinity (>2.6) gradually increases. In quartz vein mineralization, the wavelength gradually increases from the periphery (<2203 nm) to the center (2210–2211 nm), while the crystallinity does not change significantly and in a small value (<1.5). The wavelength variation range of breccia mineralization is 2198~2214 nm and is concentrated in 2201~2204 nm near the center, while the overall crystallinity is lesser than 5.5 and concentrated around 1–2.2 near the center. The wavelength and crystallinity of muscovite are mainly affected by Tschermak substitution and temperature. When the contents of Si, Fe, and Mg are low and AlVI is high, the wavelength tends toward the short-wave (SW) direction, while the opposite tends toward the long-wave (LW) direction. The high crystallinity (4.1–8.4) of muscovite can be used as an indicator of porphyry gold mineralization and also provides an important indicator to explore similar types of gold deposits.

1. Introduction

In recent years, mineral spectral measurement technology has developed rapidly and has become one of the main technical methods in the field of mineral exploration, both domestically and internationally. It is widely used for extracting mineralized information from altered minerals in various deposits [1,2,3,4,5,6]. Short-wave infrared (SWIR) spectroscopy, with a wavelength range of 1300 to 2500 nm, can effectively identify minerals containing hydroxyl, amino groups, sulfates, and carbonates [7,8,9,10,11,12], as well as delineate alteration zoning [13,14] and hydrothermal mineralization centers [15,16,17,18]. Due to the portability and fast analysis speed of SWIR technology, it has been applied in ore prospecting across multiple deposits [18,19,20,21,22]. Porphyry and epithermal deposits are two types of magmatic-hydrothermal deposits with close spatiotemporal and genetic relationships [23]. Previous studies on porphyry-epithermal deposits have focused on geological characteristics [24], metallogenic epochs [25], and metallogenic models [26]. In recent years, some scholars have applied SWIR spectral technology to the prospecting and exploration of porphyry copper (gold-molybdenum) deposits and epithermal gold deposits, achieving good results [27,28,29], but research on SWIR spectral prospecting indicators for porphyry gold deposits is basically blank. For example, Harraden [29] studied the Pebble porphyry copper–gold–molybdenum deposit in Alaska, United States, and found that high-grade Cu and Au were consistent with short-wave (SW) muscovite. Tang [30] predicted in the deep of the borehole ZK2404, at an elevation of approximately 4100–4300 m, with shorter Al-OH absorption wavelengths (<2203 nm) and higher crystallinities (>5.5) in the sericite group minerals of the Tiegelongnan porphyry-epithermal copper (gold) deposits as hydrothermal centers. In addition, some studies also suggest that the closer to the center of the ore body, the longer the wavelength of muscovite minerals and the higher the crystallinity. For example, Wang [31] pointed out that the Al-OH absorption wavelengths of sericite are biased toward the long-wave (LW) direction (2208~2220 nm), which is related to the gold mineralization of the Zhengguang epithermal gold-zinc deposit. Shao [32] found a deep tectonic altered ore body near the Jiaodong Xincheng gold deposit, where illite IC (the crystallinity of muscovite group minerals in SWIR spectroscopy (SWIR-IC, also called “IC”) [33,34]. The representation method is the ratio of Dep2200 to Dep1900 [35]) ≥ 1.2 (near 3–4.8) and sericite Pos2200 (The corresponding characteristic absorption peak of muscovite Al-OH is near 2200 nm, which is called “muscovite Al-OH absorption peak wavelength Position (Pos2200)”; the absorption depth of the corresponding absorption peak is called “muscovite Al-OH absorption peak depth Deep (Dep2200)” [30]) ≥ 2205 nm can be used as prospecting indicators. It can be seen that SWIR spectral technology has good indicative significance for determining the prospecting direction of deposits, but there are still differences in the infrared spectral exploration identification of different deposits, and its change mechanisms and laws need to be summarized with more examples.
The Yixingzhai gold deposit is a typical gold deposit in the Wutaishan-Hengshan gold district and the largest gold deposit in Shanxi Province [36]. The gold reserves in Yixingzhai exceeds 91 t according to [37], which has significant economic value. Many scholars have carried out various studies on the three mineralization types (porphyry, quartz vein, and breccia) in the Yixingzhai gold deposit, such as ore genesis [38,39], geochemical characteristics [36,40], metallogenic epoch [41], crystallization temperature [42], metallogenic dynamics [43], etc. However, research on exploration indicators in different mineralization types is still very limited. Therefore, the present study, based on detailed field observation and systematic petrographic work, conducted a detailed study on the alteration zoning in minerals and spectral characteristics of the Yixingzhai gold deposit using SWIR spectral technology. For the first time, SWIR spectrum exploration indicators for porphyry gold deposits were established, and as the first discovery of muscovite in porphyry gold deposits has higher crystallinity (4.1–8.4) than porphyry copper deposits (1.6–3), epithermal gold deposits (1–3), and tectonic altered gold deposits (1.1–2.7), it provides a new basis for the prospecting and exploration in the Yixingzhai as well as porphyry gold deposits.

2. Geological Background

2.1. Geological Characteristics of the Mining Area

The Yixingzhai gold deposit is located in the Wutai-Hengshan area of the central Asian orogenic belt in the North China Craton during the Paleoproterozoic era (Figure 1a). The early Precambrian basement rocks of the Hengshan terrain are termed the Hengshan Complex, Wutai Complex, and Fuping Complex from north to south, with some geological bodies covered by the Paleoproterozoic Hutuo group, which is dominantly composed of volcanic and clastic rocks [40,44]. The lithology of the region is mainly composed of archean TTG, paleoproterozoic Hutuo group, proterozoic ultramafic rocks, and proterozoic metamorphic sedimentary rocks. The fault structures in the region are well-developed, primarily in the NW and NEE directions. The NW-trending faults are mostly formed by the vertical movement and torsion of the Yanshan crust. These faults provide structural conditions for the formation of the deposit. The NEE-trending faults are developed as Precambrian basement structures, and the low-angle bedding shear zones dominated by extrusion properties are also developed [38] (Figure 1b). Regional magmatic activities are frequent, occurring during the Wutai, Yanshan, and Himalayan periods, among which the Yanshan magmatic activity is most closely related to mineralization [36,38].

2.2. Characteristics of the Deposit

The Yixingzhai gold deposit is the largest gold deposit in Shanxi Province with great resource potential. It mainly develops two types of ore bodies: porphyry, quartz vein, and breccia (Figure 2). The surrounding rock of the basement of the mining area is the Hengshan complex, and the main lithologies are biotite amphibole plagioclase gneiss, amphibolite, felsic gneiss, etc. [36]. The fault system in the mining area is characterized by multi-stages, mainly developing two groups of NW-trending and NNW-trending faults. The NW-trending faults are the main rock-controlling and ore-controlling structures in the mining area. The NNW-trending faults are mainly ore-bearing structures in the mining area, which are the main places for the precipitation of ore-forming materials and control the spatial distribution of gold ore bodies [45]. The Yanshan magmatic rocks in the mining area are mainly diorite dykes, diabase dykes, acid subvolcanic rocks, the Sunzhuang diorite complex, etc. [38,46]. The Sunzhuang diorite complex is located in the south of the mining area, which is mainly composed of porphyritic granite and quartz monzodiorite [40,46]. The acid subvolcanic rocks are mainly distributed within and around the four breccia pipes of Hewan, Tietangdong, Jinjiling, and Nanmenshan, with Hewan being the largest exposed area, and the ore-bearing lithologies are mainly plagioclase quartz porphyry, quartz porphyry, etc.
More than a dozen gold-bearing quartz veins of varying sizes are developed in the mining area, some of which are evenly spaced. The NW-trending fault structure controls the distribution of quartz vein gold ore bodies. According to the mineral assemblage and cross-cutting relationships, the main mineralization is divided into four stages: the quartz-sericite stage, the quartz-pyrite stage, the quartz polymetallic stage, and the calcite stage. The quartz-pyrite stage is the principal mineralization stage [47].
The Tietangdong skarn breccia pipe is the most typical breccia gold ore body in the mining area. Its composition is complex, and its economic value is high. Not only is the gold-bearing ore body found, but also an iron ore body is found. In addition, the vein rocks in the mining area are extremely developed, mainly consisting of diabase dykes and lamprophyre dykes, which are mostly irregularly interspersed throughout the mining area [36].
Previous geochronological studies have been carried out on the Yixingzhai deposit. The 40Ar/39Ar ages of muscovite in porphyry gold deposits and vein gold deposits are 139 Ma and 138 Ma, respectively [38], which are essentially consistent with the Re-Os and zircon U-Pb ages of molybdenite in quartz porphyry [36,44]. The U-Pb age of garnet in skarnized breccia is 140 Ma, and the zircon U-Pb age of quartz porphyry cutting breccia is 141 Ma [46]. The zircon ages of the Sunzhuang porphyritic granite and quartz monzodiorite are 134 Ma and 134–135 Ma, respectively [40,47]. In summary, diagenesis and mineralization ages of the Yixingzhai deposit are concentrated around 134–140 Ma.

2.3. Characteristics of Alteration and Mineralization

The main mineralization types in Yixing Village are porphyry mineralization, quartz vein mineralization, and breccia mineralization. The main lithologies in the mining area are plagioclase quartz porphyry, biotite amphibole plagioclase gneiss, breccia, etc. (Figure 2). Plagioclase quartz porphyry is mainly developed in the Hewan area, primarily composed of feldspar and quartz (Figure 3a–c). There are also small-scale breccia pipes in porphyry gold deposits, most of which are crypto-explosive breccia and amphibolite. The quartz vein gold deposits are mostly produced in the biotite amphibole plagioclase gneiss in a nearly vertical state. As the ore-bearing surrounding rock of quartz vein gold deposits, biotite amphibole plagioclase gneiss is mainly composed of quartz, biotite, and other minerals (Figure 3d,e). Breccia is mainly developed in the Tietangdong breccia pipe, and chlorite of boulders can be seen within the breccia (Figure 3f). The alteration characteristics in the mining area are pronounced, with sericitization (Figure 3a and Figure 4a,b) generally developed, as well as silicification (Figure 3b), hematite mineralization (Figure 3c), epidotization (Figure 3d,f), chloritization (Figure 3e,f and Figure 4a,c), carbonation (Figure 4b), etc. The metal minerals are mainly pyrite (Figure 4d), as well as a small amount of chalcopyrite (Figure 4d), sphalerite (Figure 4d), galena (Figure 4e), hematite (Figure 4f), specularite (Figure 4f), etc., among which beresitization is the most closely related to mineralization.
In porphyry mineralization, muscovite is mostly altered from plagioclase, which appears fine and scaly under the microscope. The color is orange, and the particle size is about 10 μm. According to the mode of alteration, it can be divided into the complete alteration of plagioclase to sericite (Figure 5a), and the other type develops along the plagioclase cleavage (Figure 5b). In quartz vein mineralization, muscovite is associated with quartz veins or quartz + pyrite veins and is produced in the form of halo around the vein body. The particle size is mostly 50 μm to 100 μm, accompanied by calcite (Figure 5c,d). Sericite in breccia mineralization is mostly altered from biotite. The particle sizes vary, and some of the alterations are complete. The color is mainly teal and orange, and it is accompanied by chlorite (Figure 5e,f).

3. Sampling and Methods

3.1. Sample Collection and Testing

In this work, the Hewan porphyry gold deposit, quartz vein gold deposit, and Tietangdong breccia gold deposit were chosen as the main research objects. According to the proximity of the ore bodies, three exploration profile lines—No. 1, No. 2, and No. 6—were selected, and five boreholes—22SZK102, B827ZK510, ZK102, 22DZK301, and B827ZK107—of Line No. 1 were selected. Line No. 2 included eleven boreholes: B827ZK102, ZK206, B827ZK204, B827ZK201, B827ZK207, B525ZK104, ZK204, B525ZK102, B525ZK203, 6DZK201, and T510ZK001, while Line No. 6 included nine boreholes: B827ZK605, ZK601, 22DZK603, B710ZK602, 6DZK602, 3DZK402, T830ZK601, T510ZK601, and T510ZK803. A total of 25 boreholes were tested using SWIR spectroscopy. The measured boreholes were recorded, photographed, and tested in detail. The test site was located in the core library of Shanxi Zijin Mining Co., Ltd., Taiyuan, China, and the total test length of boreholes was about 8700 m. After the test, the measured samples were summarized and put back into the core library in time. In this study, measurements were taken every 2 m close to the center of the ore body and every 5 m at the periphery of the ore body. Each sample was tested for three data points, and the test time was 5 to 7 s, while the time for dark minerals was appropriately extended to 10 s. Corrections were carried out every 15 to 20 min. A total of 1780 samples were tested in the study area, and a total of 5342 spectral data points were obtained.
The analysis and testing were conducted in the School of Earth Science and Resources at the China University of Geosciences (Beijing). The instrument used was the TerraSpec Halo portable mineral spectrometer, produced by ASD Company in the United States, which is designed for field geologists to quickly identify altered minerals. The detection range of the SWIR spectrum is 350 to 2500 nm, and the sampling interval is 2 nm. Before the test, the samples were washed and dried, and then the instrument was calibrated. The instrument’s spectral parameter was set to 200, and the reference white was set to 400. The sample was measured when the spectral line was straight. The instrument was kept close to the sample to avoid interference caused by external light. The test points were selected to avoid, as far as possible, sulfides, quartz veins, xenoliths, and other areas [15,16].

3.2. Analytical Methods

The spectral data were processed using the software “The Spectral Geologist Version 8 (TSG 8)” developed by the Australian Federal Scientific and Industrial Research Organization (CSRIO) to automatically identify minerals and compare with the standard database, which can effectively identify minerals containing Al-OH, H2O, Fe-OH, Mg-OH, etc. The parameters, such as the characteristic absorption peak wavelength and absorption depth of altered minerals, were extracted from the normalized reflectance spectrum (HullQuot) in the TSG software. Moscovite mainly has three characteristic groups: Al-OH, H2O, and -OH, and the characteristic absorption peaks appear near 1400 nm, 1900 nm, and 2200 nm. The crystallinity parameters of muscovite minerals are extracted with reference to [18,48]. Finally, the final mineral species were determined by manual inspection and proofreading. In the spectrum, muscovite (sericite) and illite were not easily distinguished; thus, muscovite and illite were collectively referred to as muscovite minerals. Because the Al-OH characteristic absorption peak of the muscovite group minerals can be easily affected by kaolinite, montmorillonite, and other minerals, data affecting spectral accuracy and those with low signal-to-noise ratios in the sample were eliminated.
Electron probe microanalysis (EPMA): The test work was carried out in the electron probe laboratory of the Institute of Geology, Chinese Academy of Geological Sciences. The typical altered mineral, muscovite, in the study area was analyzed using an electron microprobe analyser (EPMA; JXA-8100, JEOL, Tokyo, Japan) with a 15 kV accelerating voltage, 20 nA probe current, and 5 μm beam diameter, and the indoor temperature was 19 °C. Before the experiment, the test samples were coated with carbon to ensure accurate testing, and the test points were selected in clean and smooth areas to avoid the influence of other impurities. SiO2, Al2O3, MgO, MnO, CaO, Na2O, K2O, FeO, TiO2, Cr2O3, and NiO were analyzed. Line and spectrometer crystal used for major element were as follows: Si (Kα, TAP), Na (Kα, TAP), K (Kα, PETJ), Al (Kα, TAP), Mg (Kα, TAP), Mn (Kα, LIFH), Fe (Kα, LIFH), Cr (Kα, LIFH), Ni (Kα, LIFH), Ti (Kα, PETJ), Ca (Kα, PETJ), F (Kα, TAP), Ba (Kα, PETJ), and Cl (Kα, PETJ). Count times were 10 s for peak and 5 s for background per element. Natural minerals from SPI were used for standardization. ZAF corrections were carried out. The estimated precisions for major elements were ±2%.

4. Results

4.1. EPMA Results

In this study, different wavelengths of muscovite were selected for the three mineralization types, and eleven samples were selected for EPMA testing according to their relationship with the center of the ore body. The test results are shown in Table 1. According to the relationship with the center of the ore body, five samples with different wavelengths were selected in the porphyry mineralization area, with a total of 48 test points. B827ZK201-70 (2201 nm) is located in the center of the ore body, while ZK204-316 (2204 nm), B827ZK605-19 (2208 nm), B827ZK107-248 (2210 nm), and ZK601-381.56 (2214 nm) are far away from the center of the ore body. Three samples were selected for quartz vein mineralization, and a total of 20 test points were selected. The samples 6DZK602-216.1 (2211 nm) and 3DZK402-194 (2213 nm) are located in the center of the ore body, while 6DZK602-130 (2202 nm) is far away from the center of the ore body. Three samples were selected from the breccia mineralization area, and a total of 31 test points were selected. The samples T510ZK803-540 (2201 nm) and T510ZK601-19 (2208 nm) are located in the center of the ore body, while T510ZK601-231 (2204 nm) is far away.
The muscovite content of w(SiO2) in the porphyry mineralization is 46.48% to 50.59%, with an average of 48.48%; w(Al2O3) content ranges from 26.73% to 34.99%, with an average of 31.08%; w(FeO) content ranges from 0.85% to 5.57%, with an average of 2.4%; w(MgO) content ranges from 0.21% to 3.84%, with an average of 1.44%. The quartz vein mineralization of muscovite has higher w(SiO2) (47.2% to 52.95%, with an average of 49.15%) and w(MgO) (0.24% to 2.68%, with an average of 1.69%), but lower w(FeO) (0.33% to 3.87%, with an average of 1.41%) than the porphyry mineralization. The breccia mineralization of muscovite has higher w(Al2O3) (29.22% to 36.02%, with an average of 32.7%) and w(MgO) (0.63% to 5.9%, with an average of 1.87%), but lower w(SiO2) (45.21% to 50.66%, with an average of 47.76%) and w(FeO) (0.4% to 4.03%, with an average of 1.46%) than the porphyry mineralization. In general, the content of w(SiO2) and w(Al2O3) in muscovite of Yixingzhai is higher, and the content of w(FeO) and w(MgO) is lower, which has the characteristics of high Si, Al, and low Fe, Mg.

4.2. Short-Wave Infrared Spectroscopy Alteration Mineral Assemblages and Alteration Zoning

4.2.1. Alteration Minerals and Alteration Assemblages

In the Yixingzhai mining area, muscovite group minerals (muscovite, phengite, paragonite, and illite), amphibole group minerals (hornblende and actinolite), chlorite group minerals (FeMg-chlorite, Mg-chlorite, and Fe-chlorite), montmorillonite minerals, kaolinite group minerals (PX-kaolinite and WX-kaolinite), carbonates (calcite and ankerite), epidote, and a small amount of saponite, biotite, and other minerals (Figure 6a) were mainly identified by SWIR. Muscovite group minerals are most widely distributed in the mining area.
The value of the Pos2200 wavelength of muscovite will “drift” due to the influence of composition. According to the wavelength of Pos2200 from short to long, it can be divided into paragonite, muscovite, and phengite. When identified as paragonite and rich in Al and Na, the Pos2200 value is less than 2203 nm; when identified as phengite and poor in Al but rich in Si, the Pos2200 value is higher than 2208 nm [49]. The Pos2200 value of muscovite in Yixing ranges from 2198 to 2214 nm, with widely distributed muscovite concentrated between 2206 and 2208 nm, containing a small amount of paragonite (Pos2200 ≤ 2203 nm) and phengite (Pos2200 ≥ 2209 nm) (Figure 6b). The specific data are shown in Table S1.
Mineral assemblages of different mineralization types are different (Figure 7): In porphyry mineralization, borehole B827ZK201 is taken as an example. The main mineral assemblage consists of muscovite group minerals, accounting for about 90%, with a small amount of other clay minerals. In quartz vein mineralization and breccia mineralization, boreholes 6DZK602 and T510ZK803 are taken as examples, respectively. In these two mineralizations, muscovite group minerals are commonly combined with chlorite, epidote, amphibole, etc. The content of muscovite minerals accounts for about 30%.

4.2.2. Alteration Zoning

A detailed study of the Hewan porphyry gold ore body was carried out. From the center of the ore body to the outside, it is roughly divided into the hematite zone, kaolinization zone, strong sericitization zone, sericitization zone, and weak sericitization zone, and mineralization is closely related to sericitization (Figure 8). The hematitization and kaolinization zones are located in the center of the porphyry gold deposit. The main altered minerals are kaolinite and muscovite. The main altered minerals in the peripheral sericitization zone are muscovite and illite. The surrounding rock alterations near the quartz vein gold deposit mainly include sericitization, silicification, and chloritization. Chloritization and epidotization are generally developed in the breccia gold deposits, and skarnization occurs in the deep part near the ore body.

4.3. Variation Characteristics of Muscovite Mineral Spectral Parameters

The variation characteristics of spectral parameters in porphyry mineralization are as follows: Profile Line No. 1 is far away from the ore body, and the Pos2200 value of muscovite in the porphyry is higher than 2206 nm overall, which is biased toward the LW direction (Figure 9a). The crystallinity changes significantly; the IC value in the breccia pipe is less than 2.5, while the IC value of porphyry ranges from 1.6 to 7.0 and is concentrated around 2.6 to 4.0. Near the center of the porphyry body and at an elevation of approximately 800 m, the degree of crystallinity is relatively high. The IC value of muscovite in the feldspar quartz porphyry gradually increases from deep to shallow (Figure 9b).
The variation characteristics of the spectral parameters of the porphyry body in Profile Line No. 2 are as follows: away from the ore body, the Pos2200 value of muscovite is higher than 2206 nm, which is biased toward the LW direction. The wavelength range within the ore body is 2201 to 2212 nm. The Pos2200 value of muscovite near the center of the ore body is concentrated between 2201 and 2205 nm, which is biased toward the SW direction (Figure 10a). The variation law of crystallinity is as follows: the IC value of muscovite far from the ore body in the porphyry body is low and concentrated between 1.6 and 2.5. The IC values within the ore body range from 1.6 to 8.4, but the IC value near the center of the ore body is concentrated between 2.6 and 4.0. A crystallinity anomaly area appears near the elevation of 800 m (IC > 4.1). The main lithologies of ZK206 and ZK204 are plagioclase quartz porphyry and amphibolite. The crystallinity changes significantly; the IC value of muscovite in plagioclase quartz porphyry ranges from 1.6 to 7.0 and is concentrated between 2.6 and 4.0. The IC value in plagioclase quartz porphyry gradually increases from deep to shallow. The IC value of muscovite developed in amphibolite ranges from 2.6 to 5.5 and is concentrated between 2.6 and 4.0. The IC value of muscovite developed in breccia varies greatly and is concentrated between 1.6 and 4.0 (Figure 10b).
The variation characteristics of spectral parameters of the porphyry body in Profile Line No. 6 are as follows: away from the ore body, the value of muscovite Pos2200 is higher than 2206 nm, which is biased toward the LW direction. However, the wavelength near the ore body is biased toward the SW direction, similar to Profile Line No. 1 and No. 2. The borehole B710ZK602 in the ore body has a higher wavelength near the elevation of 650–700 m, which should be affected by the breccia pipe. Borehole B827ZK605, around 750–850 m, is far from the center of the ore body and has a higher wavelength (Figure 11a). The crystallinity of the porphyry body away from the ore body is concentrated between 1.6 and 2.5. The crystallinity near the ore body ranges from 1.6 to 8.4 and is concentrated between 2.6 and 4.0. The IC value of muscovite in plagioclase quartz porphyry increases gradually from deep to shallow. The IC value of muscovite in breccia, measured in boreholes ZK601 and B710ZK602, is concentrated around 1.5. The crystallinity of muscovite developed in basement gneiss in borehole 22DZK603 is low and less than 1.5 (Figure 11b).
The variation characteristics of spectral parameters in quartz vein mineralization are as follows: Quartz veins of varying sizes are developed within the gneiss of the surrounding rock in Yixingzhai. The muscovite wavelength in the gneiss is generally low, typically less than 2203 nm, and tends toward the SW direction. The muscovite Pos2200 value near the quartz gold veins is higher, indicating phengite, and the wavelength is concentrated around 2211 nm (Figure 12a). The crystallinity of muscovite near the quartz gold veins is low, typically less than 1.5 (Figure 12b).
The variation characteristics of spectral parameters in Breccia Mineralization are as follows: The Tietangdong breccia pipe is the largest one in the Yixingzhai mining area. The SWIR spectral test of muscovite in the breccia pipe on Exploration Line No. 6 shows that the wavelength of muscovite ranges from 2198 to 2214 nm. In gneiss breccia, far away from the ore body, the Pos2200 value of muscovite ranges from 2201 to 2205 nm. The range of muscovite Pos2200 in the ore body is between 2198 and 2208 nm and concentrated in the vicinity of 2201 to 2204 nm, which is biased toward the SW direction (Figure 13a). The crystallinity of muscovite is less than 5.5 overall, and the IC value in gneiss breccia is less than 1.5. The IC value in the ore body is less than 5.5 and concentrated in the vicinity of 1 to 2.2 (Figure 13b).
The study on the variation of spectral parameters in different mineralization types shows that muscovite in porphyry mineralization gradually tends to be SW direction from the periphery to the center of the ore body, and the crystallinity near the center of the ore body gradually increases. Therefore, the Pos2200 value (2201 to 2204 nm) and crystallinity (IC > 2.6) of muscovite can be used as indicators of porphyry mineralization. Quartz vein mineralization is gradually inclined toward the LW direction from the periphery to the center of the ore body, and the crystallinity value is low. The muscovite Pos2200 value (2210 to 2211 nm) and crystallinity (IC < 1.5) can be used as indicators of quartz vein mineralization. In breccia mineralization, the ore body is close to the SW direction. The muscovite Pos2200 value (2201 to 2204 nm) and crystallinity (1 to 2.2) can be used as indicators of breccia mineralization.
The summary reveals that the Pos2200 spectral characteristic of muscovite across the three types of mineralization has similar ranges, but the average value of muscovite Pos2200 in porphyry mineralization (2206 nm) is slightly higher than in the quartz vein mineralization (2202 nm) and breccia mineralization (2203 nm). The average IC value of muscovite in porphyry mineralization (3.3) is significantly higher than in quartz vein mineralization (0.9) and breccia mineralization (1.4). It can be seen that the three mineralization types can be well distinguished by crystallinity; moreover, the maximum IC value of muscovite in porphyry can reach 8.4. The reason for the high crystallinity of muscovite needs further discussion (Figure 14).

5. Discussion

5.1. The Influence Factors of Spectral Parameters Change of Muscovite

5.1.1. Components

The Al-OH characteristic absorption peak position of muscovite is affected by hydrothermal fluid temperature, pH, and other factors, mainly affected by Tschermak replacement: VIAl3+ + IVAl3+ ↔ nIVSi4+ + VI (Fe2+, Mg2+, Mn2+) [50,51]. Due to changes in the content of Si, Al, Fe, and Mg, this results in the drift of the Al-OH characteristic absorption peak position [52,53]. The octahedral sites in muscovite are mainly occupied by AlVI, Fe, and Mg, while the tetrahedral sites are mainly occupied by AlIV and Si [54]. Combined with the analysis of muscovite in the three types of mineralization, it is found that Si has a negative correlation with AlIV at the tetrahedral position, and there is an obvious substitution reaction (Figure 15a). At the octahedral position, Mg, Fe, and Fe + Mg are negatively correlated with AlVI, and there are obvious substitution reactions (Figure 15b–d).
Research has shown that the characteristic absorption peak of muscovite Al-OH is mainly related to the AlVI structure in muscovite. The higher the content of AlVI, the lower the Pos2200 value of muscovite and the tendency toward the SW direction. The lower the content of AlVI, the higher the Pos2200 value of muscovite and the tendency toward the LW direction, which shows a negative correlation [19,35,55,56]. When the Pos2200 value of muscovite in the three mineralization types at Yixingzhai is higher, the content of AlVI is lower, and the content of Si, Fe, and Mg is higher, tending toward the LW direction. When the content of AlVI is higher and the content of Si, Fe, and Mg is lower, the wavelength tends toward the SW direction. The wavelength of the characteristic absorption peak of muscovite Al-OH is negatively correlated with AlVI (Figure 16a) and positively correlated with Si, Fe, and Mg (Figure 16b–d). It can be seen that the wavelength of muscovite is affected by the Tschermak replacement mechanism, and the wavelength “drift” phenomenon occurs due to the different content of elemental components [35,39,57].

5.1.2. Temperature and pH

The wavelength of muscovite is affected by the Tschermak substitution reaction, and the temperature is an important factor in the substitution process. Under high-temperature conditions, muscovite has the most ideal partition model, but as the temperature decreases, the Al and K in the lattice are gradually replaced by Si and some defects [58]. According to previous studies, muscovite with a shorter wavelength is in a relatively high-temperature and high-pressure hydrothermal environment, while muscovite with a longer wavelength is in a relatively low-temperature and low-pressure hydrothermal environment [35,52,59]. Therefore, combined with the geological characteristics of Yixingzhai, previous studies have shown that the age of the porphyry gold deposit is slightly earlier than the quartz vein gold deposit [38]. The ore-forming materials and fluids related to porphyry are mainly derived from the exsolved magmatic-hydrothermal fluid in the deep magmatic chamber homologous to the Hewan porphyry [38]. Combined with spectral data, the temperature of Yixingzhai porphyry mineralization near the center of the ore body is higher, and the characteristic absorption peak wavelength of muscovite Al-OH is biased toward the SW direction. As the magmatic-hydrothermal fluid in the porphyry body moves outward along the fissure, the temperature gradually decreases, and the hydrothermal fluid fills and precipitates to form a quartz vein gold deposit. Therefore, the characteristic absorption peak wavelength of muscovite Al-OH shows the opposite trend compared with porphyry mineralization. With the outward migration of porphyry hydrothermal fluid, the temperature gradually decreases, the increase in water content leads to an increase in the 1900 nm absorption peak, and the decrease in Al content leads to a decrease in the 2200 nm characteristic absorption peak of muscovite, which results in a decrease in the IC value. Therefore, the average IC value of muscovite in porphyry mineralization (3.3) is significantly higher than that in quartz vein mineralization (0.9) and breccia mineralization (1.4). The crystallinity (IC > 2.6) of porphyry mineralization near the center of the ore body is also significantly higher than that of quartz vein mineralization (IC < 1.5) and breccia mineralization (1 to 2.2). Strong sericitization alteration occurs near the 800 m elevation of the porphyry ore body, and high-grade gold mineralization with high crystallinity (IC ≥ 4.1) is evenly distributed in the lower part of the hydrothermal breccia aggregate captured by the porphyry [38]. At the same time, combined with electron probe data analysis (Figure 15a), it can be seen that the crystallinity of muscovite is higher when the temperature is higher, corresponding to higher Al content and a lower Al-OH characteristic absorption peak wavelength. As the temperature decreases, crystallinity decreases, corresponding to lower Al content and a higher Al-OH characteristic absorption peak wavelength. Therefore, temperature is an important factor affecting the wavelength and crystallinity of muscovite.
In addition to the influence of temperature, the absorption wavelength of muscovite is also affected by the pH of the hydrothermal fluid. The main lithology of the Yixingzhai porphyry mineralization is plagioclase quartz porphyry, and muscovite is mainly formed by hydrolysis and alteration of feldspar. The formation process of muscovite consumes acid (H+), and the reaction formula is NaAlSi3O8-CaAl2Si2O8 (plagioclase) + 2HCl + KCl → K{Al2 [AlSi3O10]-(OH)2} (muscovite) + 2SiO2 (quartz) + NaCl + CaCl2 [19]. As the reaction progresses, the temperature gradually decreases, so the Al-OH wavelength of muscovite away from the center of porphyry mineralization is relatively biased toward the LW direction. However, SW muscovite and LW muscovite will also convert under certain conditions, with the reaction formula being 2KAl2 (AlSi3) O10 (OH)2 (muscovite) + K+ + 1.5 (Fe2+ and Mg2+) + 4.5SiO2 + 3H2O ⇌ 3KFe0.5 (Al0.5Si3.5) O10 (OH)2 (phengite) + 4H+ [50,52]. It can be concluded from the reaction formula that muscovite is formed in a relatively acidic environment, but the formation environment of phengite is relatively neutral [19]. During the migration of Yixingzhai magmatic-hydrothermal fluid from the center to the periphery, the infiltration of the fluid will be quickly neutralized by the surrounding rock, indicating that the acidic environment will be transformed into a neutral environment. Therefore, SW muscovite is mainly formed near the mineralization center, while LW phengite is mainly formed far away from the mineralization center.

5.2. Comparison with Other Deposits

The characteristics of short-wave infrared spectroscopy of muscovite group minerals have been widely used in the prospecting and exploration of porphyry deposits [15,16,18,29,55,60]. Combined with the analysis of prospecting indicators and influencing factors of spectral characteristic parameters of typical porphyry copper deposits (Table 2), the Al-OH characteristic absorption peaks of muscovite in porphyry copper deposits, such as Yulong and Pulang, are biased toward the LW direction, which can be used as a sign to indicate the mineralization center [61,62,63]. However, Niancun, Highland Valley, and Zhunuo porphyry copper deposits show the opposite trend [18,57,64]. The difference in Al-OH characteristic absorption peaks of muscovite is caused by the influence of chemical composition and pH in different deposit types. However, according to the analysis of the crystallinity of important spectral characteristic parameters, the maximum crystallinity of muscovite minerals in porphyry copper deposits is about 3, and the crystallinity of 1.6 to 3 is generally used as a sign of indicating the mineralization center [57,61,64]. The crystallinity of epithermal or tectonically altered rock gold deposits is generally low [65,66,67]. The high crystallinity of the Gangcha-Kemo gold deposit may be affected by the deep porphyry metallogenic system [27]. The crystallinity of other deposits is similar to the Yixingzhai hydrothermal veins gold deposit but lower than the porphyry gold deposit. Comprehensive analysis of the high crystallinity (4.1 to 8.4) of muscovite in the Yixingzhai porphyry gold deposit can be used as an indicator of gold mineralization. In addition, as the first discovery of muscovite in porphyry gold deposit, it has higher crystallinity than porphyry copper deposits, epithermal, and tectonically altered rock gold deposits, which provides an important basis for finding similar types of gold deposits.

6. Conclusions

(1)
In the porphyry and breccia mineralization, muscovite near the mineralization center is inclined to the SW direction, while in quartz vein mineralization, it is inclined to the LW direction. The crystallinity of porphyry mineralization is significantly higher than that of quartz vein and breccia mineralization, and the crystallinity near the mineralization center gradually increases.
(2)
The SWIR spectrum exploration identification of porphyry gold deposits was established for the first time. The spectral parameters of muscovite minerals in porphyry mineralization (Pos2200 2201–2204 nm and IC 1–2.2), breccia mineralization (Pos2200 2210–2211 nm and IC < 1.5), and quartz vein mineralization (Pos2200 2201–2204 nm and IC 1–2.2) can be used as indicators of mineralization centers.
(3)
The wavelength and crystallinity of Yixingzhai muscovite are mainly affected by the Tschermak substitution and temperature. When the content of Si, Fe, and Mg is low and the content of AlVI is high, the wavelength is biased toward the SW direction. Conversely, when the content of AlVI is low and the content of Si, Fe, and Mg is high, the wavelength tends to the LW direction. Crystallinity is mainly affected by temperature; the higher the temperature, the higher the crystallinity.
(4)
It is found for the first time that muscovite in porphyry gold deposits has higher crystallinity (4.1–8.4) than that of porphyry copper deposits, epithermal gold deposits, and tectonic altered gold deposits, which provides a new basis for the prospecting and exploration of similar porphyry gold deposits.
(5)
SWIR spectroscopy technology can identify the altered minerals of porphyry deposits quickly and determine the exploration identification effectively, which is an effective means for future prospecting and exploration.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/min15010083/s1, Table S1: The original data of wavelength and crystallinity of muscovite from Yixingzhai. Table S2: The original data of EPMA.

Author Contributions

Conceptualization, L.W. and S.W.; methodology, L.W. and S.W.; software, L.W. and S.W.; validation, L.W. and S.W.; formal analysis, L.W.; investigation, L.W., P.L., Y.Y. and Y.R.; resources, S.W., X.L., W.Y. and R.S.; data curation, L.W. and S.W.; writing—original draft preparation, L.W. and S.W.; writing—review and editing, L.W. and S.W.; visualization, L.W.; supervision, S.W.; project administration, S.W.; funding acquisition, S.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Key Research and Development Program of China (2022YFC2903601).

Data Availability Statement

Data are contained within the article and Supplementary Materials.

Acknowledgments

This study owes gratitude to the three reviewers for their valuable comments and the rock core warehouse management staff of Shanxi Zijin Mining Co., Ltd., for their assistance in transporting the rock cores and spectral testing. Here, we have gratitude for everyone who has helped with this article.

Conflicts of Interest

Xiaodan Lai and Weili Yang are employees of Zijin Mining Group Co., Ltd., Fujian. The paper reflects the views of the scientists and not the company. Rongliang Sun is an employee of Shanxi Zijin Mining Co., Ltd. The paper reflects the views of the scientists and not the company.

References

  1. Laukamp, C.; Legras, M.; Montenegro, V.; Windle, S.; Mcfarlane, A. Grandite-based resource characterization of the skarn-hosted Cu-Zn-Mo deposit of Antamina, Peru. Miner. Depos. 2022, 57, 107–128. [Google Scholar] [CrossRef]
  2. Neal, L.C.; Wilkinson, J.J.; Mason, P.J.; Chang, Z. Spectral characteristics of propylitic alteration minerals as a vectoring tool for porphyry copper deposits. J. Geochem. Explor. 2018, 184, 179–198. [Google Scholar] [CrossRef]
  3. Mathieu, M.; Roy, R.; Launeau, P.; Cathelineau, M.; Quirt, D. Alteration mapping on drill cores using a HySpex SWIR-320m hyperspectral camera: Application to the exploration of an unconformity-related uranium deposit (Saskatchewan, Canada). J. Geochem. Explor. 2017, 172, 71–88. [Google Scholar] [CrossRef]
  4. Carrino, T.A.; Crósta, A.P.; Toledo, C.L.B.; Silva, A.M. Unveiling the hydrothermal mineralogy of the Chapi Chiara gold prospect, Peru, through reflectance spectroscopy, geochemical and petrographic data. Ore Geol. Rev. 2015, 64, 299–315. [Google Scholar] [CrossRef]
  5. Hao, J.Y.; Duan, L.A.; Zhang, Y.; Zhao, H.T.; Shao, Y.J.; Guo, Y.C.; Wang, X.; Song, S.L. Machine learning on white mica short-wave infrared (SWIR) spectral data in the Tengjia Au deposit, Jiaodong peninsula (Eastern China): A prospecting indicator for lode gold deposits. Ore Geol. Rev. 2024, 173, 106230. [Google Scholar] [CrossRef]
  6. Ducart, D.F.; Crosta, A.P.; Souza Filho, C.R.; Coniglio, J. Alteration mineralogy at the Cerro La Mina epithermal prospect, Patagonia, Argentina; field mapping, short-wave infrared spectroscopy, and ASTER images. Econ. Geol. Bull. Soc. Econ. Geol. 2006, 101, 981–996. [Google Scholar] [CrossRef]
  7. Thompson, A.J.B.; Hauff, P.L.; Robitaille, A.J. Alteration Mapping in Exploration: Application of Short-Wave Infrared (SWIR) Spectroscopy; SEG Discovery: Littleton, CO, USA, 1999; pp. 1–27. [Google Scholar]
  8. Swayze, G.A.; Clark, R.N. Infrared-Spectra And Crystal-Chemistry of Scapolites—Implications For Martian Mineralogy. J. Geophys. Res. Solid Earth 1990, 95, 14481–14495. [Google Scholar] [CrossRef]
  9. Hunt, G.R. Spectral signatures of particulate minerals in the visible and near infrared. Geophysics 1977, 42, 501–513. [Google Scholar] [CrossRef]
  10. Hunt, G.R.; Ashley, R.P. Spectra of altered rocks in the visible and near infrared. Econ. Geol. Bull. Soc. Econ. Geol. 1979, 74, 1613–1629. [Google Scholar] [CrossRef]
  11. Hunt, G.R.; Wynn, J.C. Visible and near-infrared spectra of rocks from chromium-rich areas. Geophysics 1979, 44, 820. [Google Scholar] [CrossRef]
  12. Gaffey, S.J. Spectral Reflectance of Carbonate Minerals in the Visible and Near-Infrared (0.35–2.55 Microns)—Calcite, Aragonite, and Dolomite. Am. Miner. 1986, 71, 151–162. [Google Scholar]
  13. Leng, C.B.; Wang, D.Z.; Yu, H.J.; Tian, F.; Zhang, X.C. Mapping hydrothermal alteration zones with short wavelength infrared (SWIR) spectra and magnetic susceptibility at the Pulang porphyry Cu-Au deposit, Yunnan, SW China. Miner. Depos. 2024, 59, 699–716. [Google Scholar] [CrossRef]
  14. Mahdieh, H.Z.; Tangestani, M.H.; Francisco, V.R.; Yusta, I. Spectral characteristics of minerals in alteration zones associated with porphyry copper deposits in the middle part of Kerman copper belt, SE Iran. Ore Geol. Rev. 2014, 62, 191–198. [Google Scholar]
  15. Ren, H.; Zheng, Y.Y.; Wu, S.; Zhang, X.; Ye, J.W.; Chen, X.D. Short-wavelength infrared characteristics and in-dications of exploration of the Demingding copper-molybdenum deposit in Tibet. J. Earth Sci. 2020, 45, 930–944. [Google Scholar]
  16. Tian, F.; Leng, C.B.; Zhang, X.C.; Tian, Z.D.; Zhang, W.; Guo, J.H. Application of short-wave infrared spectroscopy in Gangjiang porphyry Cu-Mo deposit in Nimu ore field, Tibet. J. Earth Sci. 2019, 44, 2143–2154. [Google Scholar]
  17. Wang, R.; Cudahy, T.; Laukamp, C.; Walshe, J.L.; Bath, A.; Mei, Y.; Young, C.; Roache, T.J.; Jenkins, A.; Roberts, M.; et al. White Mica as a Hyperspectral Tool in Exploration for the Sunrise Dam and Kanowna Belle Gold Deposits, Western Australia. Econ. Geol. 2017, 112, 1153–1176. [Google Scholar] [CrossRef]
  18. Yang, Z.M.; Hou, Z.Q.; Yang, Z.S.; Qu, H.C.; Li, Z.Q.; Liu, Y.F. Application of short wavelength infrared (SWIR) technique in exploration of poorly eroded porphyry Cu district: A case study of Niancun ore district Tibet. Miner. Depos. 2012, 31, 699–717. [Google Scholar]
  19. Zhang, Z.X.; Dai, J.J.; Wang, X.G.; Hu, Z.H.; Wan, X.; Peng, B.; Fu, M.H.; Zhao, L.X. Shortwave infrared characteristics of muscovite from giant Shimensi tungsten deposit in northern Jiangxi Province and implication to exploration. Miner. Depos. 2023, 42, 116–127. [Google Scholar]
  20. Camilo, U.; Maher, K. White Mica Geochemistry of the Copper Cliff Porphyry Cu Deposit: Insights from a Vectoring Tool Applied to Exploration. Econ. Geol. 2018, 113, 1269–1295. [Google Scholar]
  21. Thimsen, E.; Sadtler, B.; Berezin, M.Y. Shortwave-infrared (SWIR) emitters for biological imaging: A review of challenges and opportunities. Nanophotonics 2017, 6, 1043–1054. [Google Scholar] [CrossRef]
  22. Laakso, K.; Peter, J.M.; Rivard, B.; White, H.P. Short-wave infrared spectral and geochemical characteristics of hydrothermal alteration at the Archean Izok Lake Zn-Cu-Pb-Ag volcanogenic massive sulfide deposit, Nunavut, Canada; application in exploration target vectoring. Econ. Geol. Bull. Soc. Econ. Geol. 2016, 111, 1223–1239. [Google Scholar] [CrossRef]
  23. Shan, S.Q.; Xie, G.Q.; Liu, W.Y.; Zheng, J.H.; Xing, B. Hydrothermal alteration and sulfide zoning characteristics of the Čukaru peki super-large porphyry-epithermal copper-gold deposit in western Tethys, serbia and its implication for exploration. Geotecton. Metallog. 2023, 47, 1085–1109. [Google Scholar]
  24. Yan, Y.F.; Tan, J.; Li, Y.H.; Ruan, S.K. Geological characteristics of epithermal gold deposits and status quo of researches in China. Resour. Environ. Eng. 2007, 21, 7–11. [Google Scholar]
  25. Zhu, X.F.; Chen, Y.J.; Wang, P.; Zhang, C.; Cai, Y.L.; Deng, K.; Xu, Q.W.; Li, K.Y. Zircon U-Pb age, geochemistry and Hf isotopes of the causative porphyry from the Bilihe porphyry gold deposit, Inner Mongolia. Front. Earth Sci. 2018, 25, 119–134. [Google Scholar]
  26. Wang, Q.; Tang, J.X.; Chen, Y.C.; Hou, J.F.; Li, Y.B. The metallogenic model and prospecting direction for the Duolong super large copper (gold) district, Tibet. Acta Petrol. Sin. 2019, 35, 879–896. [Google Scholar] [CrossRef] [PubMed]
  27. Wang, S.H.; Shen, J.F.; Peng, Z.D.; Xu, L.W.; Niu, G.; Liu, H.M.; Li, J.C.; Du, B.S.; Liu, J.J. Altered Rock characteristics and gold prospecting of Gangcha-Kemo area in Gansu province. Geoscience 2021, 35, 579–588. [Google Scholar]
  28. Xu, C.; Chen, H.Y.; White, N.; Qi, J.P.; Zhang, L.J.; Zhang, S.; Duan, G. Alteration and mineralization of Xinan Cu-Mo ore deposit in Zijinshan orefield, Fujian Province, and application of short wavelength infra-red technology (SWIR) to exploration. Min. Depos. 2017, 36, 1013–1038. [Google Scholar]
  29. Harraden, C.L.; Mcnulty, B.A.; Gregory, M.J.; Lang, J.R. Shortwave infrared spectral analysis of hydrothermal alteration associated with the Pebble porphyry copper-gold-molybdenum deposit, Iliamna, Alaska. Econ. Geol. Bull. Soc. Econ. Geol. 2013, 108, 483–494. [Google Scholar] [CrossRef]
  30. Tang, N.; Lin, B.; Li, Y.B.; Wang, Y.Y.; Li, J.J. Application of short wavelength infrared spectroscopy in porphyry-epithermal system: A case study of Tiegelongnan super-large copper (gold) deposit, Tibet. Acta Geol. Sin. 2021, 95, 2613–2627. [Google Scholar]
  31. Wang, L.; Percival, J.B.; Hedenquist, J.W.; Hattori, K.; Qin, K. Alteration Mineralogy of the Zhengguang Epithermal Au-Zn Deposit, Northeast China: Interpretation of Shortwave Infrared Analyses During Mineral Exploration and Assessment. Econ. Geol. 2021, 116, 389–406. [Google Scholar] [CrossRef]
  32. Shao, X.W.; Peng, Y.M.; Wang, G.W.; Zhao, X.Y.; Tang, J.Y.; Huang, L.L.; Liu, X.N.; Zhao, X.D. Application of SWIR, XRF and thermoelectricity analysis of pyrite in deep prospecting in the Xincheng gold orefield, Jiaodong Peninsula. Front. Earth Sci. 2021, 28, 236–251. [Google Scholar]
  33. Doublier, M.P.; Roache, T.; Potel, S. Short-wavelength infrared spectroscopy; a new petrological tool in low-grade to very low-grade pelites. Geology 2015, 38, 1031–1034. [Google Scholar] [CrossRef]
  34. Yang, K.; Browne, P.R.L.; Huntington, J.F.; Walshe, J.L. Characterising the hydrothermal alteration of the Broadlands-Ohaaki geothermal system, New Zealand, using short-wave infrared spectroscopy. J. Volcanol. Geotherm. Res. 2001, 106, 53–65. [Google Scholar] [CrossRef]
  35. Jones, S.; Herrmann, W.; Gemmell, J.B. Short Wavelength Infrared Spectral Characteristics of the HW Horizon: Implications for Exploration in the Myra Falls Volcanic-Hosted Massive Sulfide Camp, Vancouver Island, British Columbia, Canada. Econ. Geol. 2005, 2, 273–294. [Google Scholar] [CrossRef]
  36. Zhang, L.Z. Element geochemistry and age of the altered-porphyry gold mineralization in Yixingzhai gold de-posit, Fanshi city, Shanxi province. Geol. Miner. Resour. South China 2018, 34, 134–141. [Google Scholar]
  37. Bai, X.M. Geological characteristics, geochronology, and prospecting direction of the Tietangdong cryptoexplosive breccia pipe in the Yixingzhai Gold Deposit, Shanxi Province. Gold 2022, 43, 9–18. [Google Scholar]
  38. Liu, X.G. Metallogenic characteristies and genesis analysis of Yixingzhai gold deposit in the Fanshi County of Shanxi, China. Miner. Resour. Geol. 2022, 36, 299–309. [Google Scholar]
  39. Zhang, J.Q.; Li, S.R.; Santosh, M.; Luo, J.Y.; Li, C.L.; Song, J.Y.; Lu, J.; Liang, X. The genesis and gold mineralization of the crypto-explosive breccia pipe in the Yixingzhai gold region, central North China Craton. Geol. J. 2020, 55, 5664–5680. [Google Scholar] [CrossRef]
  40. Li, S.R.; Santosh, M.; Zhang, H.F.; Luo, J.Y.; Zhang, J.Q.; Li, C.L.; Song, J.Y.; Zhang, X.B. Metallogeny in response to lithospheric thinning and craton destruction: Geochemistry and U–Pb zircon chronology of the Yixingzhai gold deposit, central North China Craton. Ore Geol. Rev. 2014, 56, 457–471. [Google Scholar] [CrossRef]
  41. Zhang, L.Z.; Gao, W.S.; Deng, X.D. Geology and Geochronology of Magmatic–Hydrothermal Breccia Pipes in the Yixingzhai Gold Deposit: Implications for Ore Genesis and Regional Exploration. Minerals 2024, 14, 496. [Google Scholar] [CrossRef]
  42. Sun, R.L. Mineralization temperature calculated from tetrahedrite thermodynamic: Implication for vein-type gold mineralization in the Yixingzhai gold deposit, Shanxi. South China Geol. 2023, 39, 581–587. [Google Scholar]
  43. Ye, R.; Tu, G.C.; Zhao, L.S.; Shen, Y.L.; Luo, L. Modes of occurrence of Au-mineral particles in Yixingzhai gold deposit and their metallogenic dynamic significance. Miner. Depos. 2002, 21, 278–282. [Google Scholar]
  44. Zhang, J.Q.; Li, S.R.; Santosh, M.; Niu, S.D.; Li, Q.; Lu, J. The magmatic–hydrothermal mineralization systems of the Yixingzhai and Xinzhuang gold deposits in the central North China Craton. Ore Geol. Rev. 2017, 88, 416–435. [Google Scholar] [CrossRef]
  45. Li, C.L.; Li, S.R.; Luo, J.Y.; Zhang, J.Q.; Song, J.Y. Characteristies of gold-bearing minerals in the Yixingzhai gold deposit, Fanshi County, Shanxi Province. Geol. China 2011, 38, 119–128. [Google Scholar]
  46. Zhang, L.Z.; Chen, L.; Wang, G.P.; Deng, X.D.; Li, J.W. Garnet U-Pb dating constraints on the timing of breccia pipes formation and genesis of gold mineralization in Yixingzhai gold deposit, Shanxi province. J. Earth Sci. 2020, 45, 108–117. [Google Scholar]
  47. Zhang, J.Q.; Li, S.R.; Santosh, M.; Li, Q.; Niu, S.D.; Li, Z.D.; Zhang, X.G.; Jia, L.B. Timing and origin of Mesozoic magmatism and metallogeny in the Wutai-Hengshan region; implications for destruction of the North China Craton. J. Asian Earth Sci. 2015, 113, 677–694. [Google Scholar] [CrossRef]
  48. Ross, P.S.; Bourke, A.; Schnitzler, N.; Conly, A. Exploration Vectors from near Infrared Spectrometry near the McLeod Volcanogenic Massive Sulfide Deposit, Matagami District, Québec. Econ. Geol. 2019, 114, 613–638. [Google Scholar] [CrossRef]
  49. Guo, N.; Huang, Y.R.; Zheng, L.; Tang, N.; Fu, Y.; Wang, C. Alteration zoning and prospecting model of epithermal deposit revealed by shortwave infrared technique: A case study of Tiegelongnan and Sinongduo Deposits. Acta Geosci. Sin. 2017, 38, 767–778. [Google Scholar]
  50. Halley, S.; Dilles, J.H.; Tosdal, R.M. Footprints: Hydrothermal Alteration and Geochemical Dispersion Around Porphyry Copper Deposits; SEG Discovery: Littleton, CO, USA, 2015; pp. 1–17. [Google Scholar]
  51. Ernst, W.G. Significance of phengitic micas from low-grade schists. Am. Miner. 1963, 48, 1357–1373. [Google Scholar]
  52. Xu, Q.J.; Ye, F.W.; Zhang, Z.X.; Zhang, C.; Li, X.C.; Li, R.W.; Tian, C. Short-wavelength infrared spectroscopy and EPMA of white mica from Baiyanghe uranium district in Xinjiang. World Nucl. Geosci. 2024, 41, 47–62. [Google Scholar]
  53. Hunt, G.R. Near-infrared (1.3–2.4 mm) spectra of alteration minerals—Potential for use in remote sensing. Geophysics 1979, 44, 1974–1986. [Google Scholar] [CrossRef]
  54. Tappert, M.C.; Rivard, B.; Giles, D.; Tappert, R.; Mauger, A. The mineral chemistry, near-infrared, and mid-infrared reflectance spectroscopy of phengite from the Olympic Dam IOCG deposit, South Australia. Ore Geol. Rev. 2013, 53, 26–38. [Google Scholar] [CrossRef]
  55. Herrmann, W.; Blake, M.; Doyle, M.; Huston, D.; Kamprad, J.; Merry, N.; Pontual, S. Short Wavelength Infrared (SWIR) Spectral Analysis of Hydrothermal Alteration Zones Associated with Base Metal Sulfide Deposits at Rosebery and Western Tharsis, Tasmania, and Highway-Reward, Queensland. Econ. Geol. 2001, 96, 939–955. [Google Scholar] [CrossRef]
  56. Duke, E.F. Near infrared spectra of muscovite, Tschermak substitution, and metamorphic reaction progress; implications for remote sensing. Geology 1994, 22, 621–624. [Google Scholar] [CrossRef]
  57. Zheng, S.L.; Wu, S.; Zheng, Y.Y.; Chen, L.; Wei, C.; Huang, P.C.; Jing, X.K.; Yu, Z.Y.; He, C.T.; Ren, H. Identifying potential porphyry copper mineralization at the Zhu’nuo ore-cluster district in western Gangdese, southern Tibet: Insights from shortwave infrared (SWIR) spectrometry and geochemical anomalies. Ore Geol. Rev. 2022, 151, 105202. [Google Scholar] [CrossRef]
  58. He, W.; Lin, B.; Song, Y.X.; Fang, X.; Wang, Q.; Yang, H.H.; Li, F.Q. Mineralogical characteristics and implications of muscovite from the Tiegelongnan super-large copper (gold) deposit in Tibet. Acta Geol. Sin. 2023, 97, 1938–1955. [Google Scholar]
  59. Zhang, S.T.; Chu, G.B.; Cheng, J.M.; Zhang, Y.; Tian, J.; Li, J.P.; Sun, S.Q.; Wei, K.T. Short wavelength infrared (SWIR) spectroscopy of phyllosilicate minerals from the Tonglushan Cu-Au-Fe deposit, Eastern China: New exploration indicators for concealed skarn orebodies. Ore Geol. Rev. 2020, 122, 103516. [Google Scholar] [CrossRef]
  60. Guo, N.; Guo, K.; Zhang, T.T.; Liu, T.H.; Hu, B.; Wang, C.W. Hydrothermal alteration distribution model of the Jiama (Gyama) copper-polymetallic deposit based on shortwave technique. Acta Geosci. Sin. 2012, 33, 641–653. [Google Scholar]
  61. Tian, C.H.; Yang, L.Q.; He, W.Y.; Zhang, S.Y.; Liu, S.T.; Wu, C. Characteristics of short wave infrared spectroscopy of sericite group minerals and their implications for exploration in the Yulong porphyry copper deposit, Tibet. Sediment. Geol. Tethyan Geol. 2022, 42, 40–49. [Google Scholar]
  62. Qiu, J.H.; Liu, W.Y.; Chen, J.W.; Lai, X.D.; Zhong, X.H.; Li, J.Y.; Long, H. Alteration mineralogy, characteristics and shortwave infrared spectroscopy of white mica in the Zijinshan ore field, Fujian Province: Implications for porphyry Cu prospecting. Ore Geol. Rev. 2024, 168, 106065. [Google Scholar] [CrossRef]
  63. Guo, D.X.; Liu, X.; Zhang, H.L.; Zhang, Z.G. The infrared spectroscopy characteristics of alteration and mineralization in the porphyry copper deposit in pulang, Yunnan province. Rock Miner. Anal. 2021, 40, 698–709. [Google Scholar]
  64. Lypaczewski, P.; Rivard, B.; Lesage, G.; Byrne, K.; D’Angelo, M.; Lee, R.G. Characterization of Mineralogy in the Highland Valley Porphyry Cu District Using Hyperspectral Imaging, and Potential Applications. Minerals 2020, 10, 473. [Google Scholar] [CrossRef]
  65. Li, X.C.; Zhang, H.D.; Hua, B.; Zhang, Z.; Lu, L. A study on metallogenic indication of epithermal deposit based on short wave infrared spectroscopy. Geol. Anhui 2023, 33, 133–138. [Google Scholar]
  66. Yao, Y.Z.; Zhu, Y.C.; Liu, J.C.; Li, W.Q. Footprints of ore fluid pathway and implications to mineral exploration in the Shihu Gold Deposit, North China: Evidence from short wave infrared spectroscopy of illitic alteration rocks. J. Geochem. Explor. 2021, 229, 106833. [Google Scholar] [CrossRef]
  67. An, B.G. Study on the Characteristics of Short-Wave Infrared Spectrum in the Alteration Zone of Shaling Gold Deposit, Shandong. Master’s Thesis, Northeastern University, Shenyang, China, 2020. [Google Scholar]
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Figure 1. (a) North China Craton tectonic geological map (Modified after [36]), (b) regional geological map of the Wutai-Hengshan Terrain (Modified after [40]).
Figure 1. (a) North China Craton tectonic geological map (Modified after [36]), (b) regional geological map of the Wutai-Hengshan Terrain (Modified after [40]).
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Figure 2. Geological map of Yixingzhai deposit. No. 1, No. 2, and No. 6 are geological exploration lines (Modified after [36,44]).
Figure 2. Geological map of Yixingzhai deposit. No. 1, No. 2, and No. 6 are geological exploration lines (Modified after [36,44]).
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Figure 3. Hand specimen characteristics of Yixingzhai. (a) Sericitized plagioclase quartz porphyry, (b) silicified plagioclase quartz porphyry, (c) hematite-altered plagioclase quartz porphyry, (d) biotite amphibole plagioclase gneiss with developed chloritization, (e) biotite amphibole plagioclase gneiss with quartz pyrite chlorite veins, (f) breccia-containing chlorite, developed with epidotization; Py—pyrite; Pl—plagioclase; Qtz—quartz; Bt—biotite; Chl—chlorite; Ep—epidote.
Figure 3. Hand specimen characteristics of Yixingzhai. (a) Sericitized plagioclase quartz porphyry, (b) silicified plagioclase quartz porphyry, (c) hematite-altered plagioclase quartz porphyry, (d) biotite amphibole plagioclase gneiss with developed chloritization, (e) biotite amphibole plagioclase gneiss with quartz pyrite chlorite veins, (f) breccia-containing chlorite, developed with epidotization; Py—pyrite; Pl—plagioclase; Qtz—quartz; Bt—biotite; Chl—chlorite; Ep—epidote.
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Figure 4. Characteristics of Yixingzhai under microscope. (a) Sericitization and chloritization, (b) muscovite alteration halo developed near quartz vein, (c) chloritization and epidotization, (d) euhedral pyrite wrapped in chalcopyrite and sphalerite, (e) galena surrounded by digenite; (f) magnetite and layered hematite enclosing fibrous specularite; Pl—plagioclase; Qtz—quartz; Chl—chlorite; Amp—amphibole; Ser—sericite; Mus—muscovite; Cal—calcite; Ep—epidote; Ccp—chalcopyrite; Sp—sphalerite; Gn—galena; Dg—digenite; Hem—hematite; Mag—magnetite; Spe—specularite. The photomicrographs (a–c) are taken in polarized transmitted light (crossed-nicols) and (d–f) in polarized reflected light.
Figure 4. Characteristics of Yixingzhai under microscope. (a) Sericitization and chloritization, (b) muscovite alteration halo developed near quartz vein, (c) chloritization and epidotization, (d) euhedral pyrite wrapped in chalcopyrite and sphalerite, (e) galena surrounded by digenite; (f) magnetite and layered hematite enclosing fibrous specularite; Pl—plagioclase; Qtz—quartz; Chl—chlorite; Amp—amphibole; Ser—sericite; Mus—muscovite; Cal—calcite; Ep—epidote; Ccp—chalcopyrite; Sp—sphalerite; Gn—galena; Dg—digenite; Hem—hematite; Mag—magnetite; Spe—specularite. The photomicrographs (a–c) are taken in polarized transmitted light (crossed-nicols) and (d–f) in polarized reflected light.
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Figure 5. Microscopic characteristics of muscovite in different types of mineralization in the Yixingzhai deposit. (a,b) The alteration of plagioclase to sericite, (c,d) the sericite halo near the quartz vein, (e,f) biotite altered to sericite and chlorite; Ser—sericite; Pl—plagioclase; Qtz—quartz; Mus—muscovite; Cal—calcite; Chl—chlorite. All photomicrographs are taken in polarized transmitted light (crossed-nicols) with the exception of (e) in polarized reflected light.
Figure 5. Microscopic characteristics of muscovite in different types of mineralization in the Yixingzhai deposit. (a,b) The alteration of plagioclase to sericite, (c,d) the sericite halo near the quartz vein, (e,f) biotite altered to sericite and chlorite; Ser—sericite; Pl—plagioclase; Qtz—quartz; Mus—muscovite; Cal—calcite; Chl—chlorite. All photomicrographs are taken in polarized transmitted light (crossed-nicols) with the exception of (e) in polarized reflected light.
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Figure 6. Histogram of the frequency distribution of different mineral species (a) and the Pos2200 value of muscovite (b) in Yixingzhai.
Figure 6. Histogram of the frequency distribution of different mineral species (a) and the Pos2200 value of muscovite (b) in Yixingzhai.
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Figure 7. Typical alteration mineral assemblages for different types of mineralization in the boreholes of Yixingzhai deposit. (a) B827ZK201, (b) 6DZK602, (c) T510ZK803. The core is missing at 600–760 m of the borehole, and the data cannot be obtained.
Figure 7. Typical alteration mineral assemblages for different types of mineralization in the boreholes of Yixingzhai deposit. (a) B827ZK201, (b) 6DZK602, (c) T510ZK803. The core is missing at 600–760 m of the borehole, and the data cannot be obtained.
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Figure 8. The alteration zoning map of the porphyry gold mineralization located on the borehole profile of the No. 2 exploration line in Yixingzhai. The figure shows the longitudinal section of No. 2 exploration line along the elevation, and the exploration line is an east-west trend.
Figure 8. The alteration zoning map of the porphyry gold mineralization located on the borehole profile of the No. 2 exploration line in Yixingzhai. The figure shows the longitudinal section of No. 2 exploration line along the elevation, and the exploration line is an east-west trend.
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Figure 9. The distribution of muscovite Pos2200 values (a) and IC values (b) in some porphyry bodies located on the borehole profile of the No. 1 exploration line. The figure shows the longitudinal section of No. 1 exploration line along the elevation, and the exploration line is an east-west trend.
Figure 9. The distribution of muscovite Pos2200 values (a) and IC values (b) in some porphyry bodies located on the borehole profile of the No. 1 exploration line. The figure shows the longitudinal section of No. 1 exploration line along the elevation, and the exploration line is an east-west trend.
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Figure 10. The distribution of muscovite Pos2200 values (a) and IC values (b) in some porphyry bodies located on the borehole profile of the No. 2 exploration line. The figure shows the longitudinal section of No. 2 exploration line along the elevation, and the exploration line is an east-west trend.
Figure 10. The distribution of muscovite Pos2200 values (a) and IC values (b) in some porphyry bodies located on the borehole profile of the No. 2 exploration line. The figure shows the longitudinal section of No. 2 exploration line along the elevation, and the exploration line is an east-west trend.
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Figure 11. The distribution of muscovite Pos2200 values (a) and IC values (b) in some porphyry bodies located on the borehole profile of the No. 6 exploration line. The figure shows the longitudinal section of No. 6 exploration line along the elevation, and the exploration line is an east-west trend.
Figure 11. The distribution of muscovite Pos2200 values (a) and IC values (b) in some porphyry bodies located on the borehole profile of the No. 6 exploration line. The figure shows the longitudinal section of No. 6 exploration line along the elevation, and the exploration line is an east-west trend.
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Figure 12. The distribution of muscovite Pos2200 values (a) and IC values (b) in some quartz veins located on the borehole profile of the No. 6 exploration line. The figure shows the longitudinal section of No. 6 exploration line along the elevation, and the exploration line is an east-west trend.
Figure 12. The distribution of muscovite Pos2200 values (a) and IC values (b) in some quartz veins located on the borehole profile of the No. 6 exploration line. The figure shows the longitudinal section of No. 6 exploration line along the elevation, and the exploration line is an east-west trend.
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Figure 13. The distribution of muscovite Pos2200 values (a) and IC values (b) in some breccia pipe located on the borehole profile of the No. 6 exploration line. The figure shows the longitudinal section of No. 6 exploration line along the elevation, and the exploration line is an east-west trend.
Figure 13. The distribution of muscovite Pos2200 values (a) and IC values (b) in some breccia pipe located on the borehole profile of the No. 6 exploration line. The figure shows the longitudinal section of No. 6 exploration line along the elevation, and the exploration line is an east-west trend.
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Figure 14. Scatter plot of muscovite Pos2200 values and IC values in different types of mineralization and lithologies at the Yixingzhai.
Figure 14. Scatter plot of muscovite Pos2200 values and IC values in different types of mineralization and lithologies at the Yixingzhai.
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Figure 15. Correlation of n (AlIV), n (Si), n (Mg), and n (Fe) in muscovite. (a) n (Si) vs. n (AlIV) diagram, (b) n (AlVI) vs. n (Mg) diagram, (c) n (AlVI) vs. n (Fe) diagram, (d) n (AlVI) vs. n (Fe + Mg) diagram.
Figure 15. Correlation of n (AlIV), n (Si), n (Mg), and n (Fe) in muscovite. (a) n (Si) vs. n (AlIV) diagram, (b) n (AlVI) vs. n (Mg) diagram, (c) n (AlVI) vs. n (Fe) diagram, (d) n (AlVI) vs. n (Fe + Mg) diagram.
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Figure 16. The relationship between muscovite chemical composition content and Pos2200 value. (a) Pos2200 (nm) vs. n (AlVI) diagram, (b) Pos2200 (nm) vs. n (Si) diagram, (c) Pos2200 (nm) vs. n (Mg) diagram, (d) Pos2200 (nm) vs. n (Fe) diagram.
Figure 16. The relationship between muscovite chemical composition content and Pos2200 value. (a) Pos2200 (nm) vs. n (AlVI) diagram, (b) Pos2200 (nm) vs. n (Si) diagram, (c) Pos2200 (nm) vs. n (Mg) diagram, (d) Pos2200 (nm) vs. n (Fe) diagram.
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Table 1. Average compositions (wt%) of muscovite by the electron probe microanalysis.
Table 1. Average compositions (wt%) of muscovite by the electron probe microanalysis.
TypesPorphyry MineralizationQuartz Vein MineralizationBreccia Mineralization
n = 48SEMn = 20SEMn = 31SEM
SiO248.480.1549.150.3247.760.31
TiO20.020.010.020.060.020.04
Al2O30.130.340.250.490.170.38
Cr2O331.080.0031.420.0032.700.00
FeO2.400.151.410.221.460.14
MnO0.050.000.060.000.060.00
MgO1.440.141.690.181.870.20
CaO0.050.010.040.020.050.02
Na2O11.600.0111.060.0611.140.02
K2O0.150.120.230.200.260.14
NiO0.020.000.020.000.020.00
Cl0.010.000.010.000.010.00
F0.240.030.100.010.090.01
BaO0.060.010.080.010.070.01
Total95.650.0595.450.0795.590.07
Based on 22 oxygen
Si6.510.026.540.036.370.04
Ti0.010.000.020.010.010.00
AlIV1.490.021.460.031.630.04
AlVI3.420.043.470.053.500.03
Total Al4.910.054.930.075.140.06
Fe0.270.020.160.030.160.02
Mn0.000.000.000.000.000.00
Mg0.290.030.340.040.370.04
Ca0.000.000.000.000.000.00
Na0.040.000.060.020.070.01
K1.990.021.880.041.890.02
OH3.900.013.960.013.970.00
Fe + Mg0.560.040.490.050.540.05
n = number of analyzed spots. The data is the average of test points.
Table 2. Statistical table of SWIR spectroscopy and influencing factors of muscovite group minerals in different deposits.
Table 2. Statistical table of SWIR spectroscopy and influencing factors of muscovite group minerals in different deposits.
ReferencesTypes and Names of DepositsSpectral Parameter RangeExploration IndicatorsThe Main Factors Affecting the Spectral Parameters
[18]Niancun porphyry copper deposit, Tibet2192–2220 nm;
0.6–3.1		Pos2200 < 2203 nm;
IC > 1.6		Temperature affects wavelength and crystallinity
[64]Highland Valley porphyry copper deposit-The average of Pos2200 is 2195 nmChemical composition
[57]Porphyry copper deposit in Zhunuo mining area2191–2219 nm; 0.75–3.14Pos2200 < 2203 nm;
IC > 2.0		Tschermak substitution affects the wavelength
[61]Yulong porphyry copper deposit2205–2209 nm;
0–3		Pos2200: 2206–2207 nm;
IC: 1.0–2.0		PH;
temperature
[60]Jiama porphyry copper deposit-Pos2200: 2200–2210 nmThe temperature decreases, and the aluminum content increases
[62]Zijinshan deep porphyry copper deposit2195–2211 nmPos2200: 2205–2211 nmTschermak substitution affects the wavelength
[63]Pulang porphyry copper deposit, Yunnan2198–2210 nmPos2200: 2205–2210 nmFluid properties; temperature
[27]Gangcha-Kemo epithermal gold deposit0–6.5 nearbyIC > 5.5Temperature affects crystallinity
[65]Epithermal gold deposit in Xiaotian-Mozitan Basin2204–2220 nm;
0–3.03		IC: 1–3 nearbyTemperature affects crystallinity
[66]Shihu altered rock gold deposit2194–2216 nm;
0–2.4		The average of Pos2200 is 2198 nmPH affects the wavelength, and temperature affects the crystallinity
[67]Shaling altered rock gold deposit2198–2220 nm;
0–2.7 nearby		Pos2200: 2207–2211 nm;
IC: 1.19–2.66		Temperature and surrounding rock composition affect the wavelength;
temperature affects crystallinity
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Wang, L.; Wu, S.; Lai, X.; Yang, W.; Sun, R.; Liu, P.; Yang, Y.; Ren, Y. The Short-Wave Infrared (SWIR) Spectral Exploration Identification and Indicative Significance of the Yixingzhai Gold Deposit, Shanxi Province. Minerals 2025, 15, 83. https://doi.org/10.3390/min15010083

AMA Style

Wang L, Wu S, Lai X, Yang W, Sun R, Liu P, Yang Y, Ren Y. The Short-Wave Infrared (SWIR) Spectral Exploration Identification and Indicative Significance of the Yixingzhai Gold Deposit, Shanxi Province. Minerals. 2025; 15(1):83. https://doi.org/10.3390/min15010083

Chicago/Turabian Style

Wang, Lifang, Song Wu, Xiaodan Lai, Weili Yang, Rongliang Sun, Peng Liu, Yandong Yang, and Yuxin Ren. 2025. "The Short-Wave Infrared (SWIR) Spectral Exploration Identification and Indicative Significance of the Yixingzhai Gold Deposit, Shanxi Province" Minerals 15, no. 1: 83. https://doi.org/10.3390/min15010083

APA Style

Wang, L., Wu, S., Lai, X., Yang, W., Sun, R., Liu, P., Yang, Y., & Ren, Y. (2025). The Short-Wave Infrared (SWIR) Spectral Exploration Identification and Indicative Significance of the Yixingzhai Gold Deposit, Shanxi Province. Minerals, 15(1), 83. https://doi.org/10.3390/min15010083

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