Mineral origin of tremolite jade artifacts from the Guojiamiao Cemetery, Eastern Zhou Dynasty, Hubei, China: based on petrology, spectroscopy, and geochemistry
Introduction
Excavated jade artifacts held great significance in ancient cultures worldwide. In Mesoamerica, jade played a crucial role in the Olmec, Maya, and Aztec civilizations, where it was believed to hold sacred power1,2. The Maya considered jade a symbol of divinity, using it in religious ceremonies and as symbols of rulership3,4. In Europe, jade was used to create tools, weapons, and ornaments due to its strong and durable nature, signifying its rarity and value5. In China, jade artifacts were seen as decorative symbols of status, power, and virtue, with many remarkable discoveries from the Liangzhu (良渚), Lingjiatan (凌家滩), and Hongshan (红山) cultures reflecting the esteemed position of jade in ancient Chinese society6,7,8. Excavated jade artifacts were integral to the formation of these ancient cultures9.
The organizational structure and social dynamics of ancient societies can be better understood through the study of mineral sources. This analysis sheds light on how precious resources were allocated and overseen by the ruling elite, offering valuable insights into the societal framework. Moreover, it provides tangible data for a thorough examination of the interactions and exchanges between diverse cultural systems. Recent studies in Mesoamerica and Europe have utilized isotopic and geochemical analyses to trace the origins of jade artifacts in Maya and Celtic cultures. These investigations have revealed evidence of long-distance trade and the spread of culture in ancient societies10,11,12,13. For instance, research has demonstrated that some jade found in the Maya civilization originated from remote highlands, indicating the intricate trade networks and social structure of that era14,15.
Among the many materials of jade, tremolite, because of its unique mineralogical attributes, was widely used in several jade-using cultural circles in prehistory. Tremolite can be classified into serpentine-type and marble-type based on the type of ore-forming parent rock16,17. The contact metasomatic marble type is the primary source of high-quality tremolite jade. Differences in structure, color, outer skin, trace elements, isotopes, and rare earth elements in jade materials from different origins can be attributed to variations in their formation period, environment, and conditions18,19. Objective judgments about the raw material sources of excavated jade artifacts can be made using methods such as the local proximity judgment method, cluster analysis, inferred mining point method, stratified research on mining point tracing, and cross-verification of typical feature analysis20,21,22,23. Chinese scholars have conducted comprehensive studies by analyzing the mineral composition of excavated jade artifacts and combining this with historical records to understand the origin, circulation routes, and usage habits of ancient Chinese jade. For example, research on jade mines in Xiuyan, Liaoning; Hetian, Xinjiang; and Gansu and Qinghai has shed light on the diversity of ancient Chinese jade artifacts and the extensive trade networks that existed24,25.
In this study, 30 samples were selected for analysis from a total of 322 jade artifacts excavated from the Guojiamiao Cemetery (郭家庙墓地) in Hubei, China, dating to the Eastern Zhou Dynasty. Employing methodologies from gemology, spectroscopy, and geochemistry, we analyzed the morphological, spectroscopic, and chemical composition characteristics of the samples. Based on these analyses, we investigated the source of the mineral materials used in the jade artifacts. This research provides essential data for further exploration of the formation, development, and evolution of the jade usage system in the Zeng State (曾国) during the Eastern Zhou period.
The archaeological context and samples
The background of Guojiamiao Cemetery
The Guojiamiao Cemetery, a large noble burial site of the Zeng State from the Late Western Zhou to Early Spring and Autumn periods, is located in the first and second groups of Zhaohu Village (赵湖村), Wudian Town (吴店镇), Zaoyang City (枣阳市), Hubei Province, China. It is situated about 20 kilometers northwest of Zaoyang’s urban area, south of the Gun River, with the Huayang River to the east, and is distributed along a north-south ridge, also known as Luojiagang (罗家岗)–Chunshugang (椿树岗)26. The cemetery can be divided into the Guojiamiao burial area and the Caomenwan burial area, separated by a low-lying area between the two ridges.
Although some tombs in this cemetery were severely looted, two rescue excavations in 2002 and 2014 still yielded a large number of artifacts, including bronzes, jade artifacts, pottery, lacquerware, and gold and silver items, among which 322 pieces are jade artifacts27. The types of jade artifacts primarily include jade rings (玉环), jade bo-shaped objects (玉帛形器), jade beads (玉珠), jade pendants (玉牌饰), jade bi (玉璧), jade cong tubes (玉琮), and jade huang pendants (玉璜) in this cemetery. The materials include tremolite, serpentine, red agate, fluorite, turquoise, mica, faience, and others. Among them, tremolite is the main material of jade artifacts unearthed in this cemetery.
Excavated jade samples
The research samples in this paper were obtained from the storehouse of the Zaoyang Cultural Relics Management Center of the Hubei Provincial Institute of Cultural Relics and Archaeology. In order to conduct the study on the origin of tremolite jade excavated from Guojiamiao Cemetery, 30 tremolite jade samples with relatively uniform texture and obvious origin characteristics were selected for this test. None of these samples had suffered severe soil erosion (Fig. 1). Their appearance and structural characteristics are listed in Table 1. To determine the mineral sources, the analysis focuses on eight features including the stone’s surface texture, surface color, impurity minerals, color, structure, major elements, trace elements, and rare earth elements.
The letters CM in the diagram denote the Cao Men Wan burials in the Guojiamiao cemetery, and GM denotes the Guojiamiao burials in the Guojiamiao cemetery. The numbers in the figure are the excavation numbers of the samples.
Analysis methods
Morphological analysis
The preliminary observation of the surface and internal features of the samples, inclusion features were observed using an optical microscope from the gemological institute, China University of Geosciences (Wuhan), and the local microscopic features were photographed using a super depth of-field stereomicroscope of Leica M205A from the gemological institute, China University of Geosciences (Wuhan), with an objective lens model of 10450191, a magnification of 0.25, a working distance of 303 mm, and a diameter of 58 mm.
Infrared spectroscopy analysis
The material identification of the samples was carried out using a micro-infrared spectrometer (Bruker Optics Hyperion 3000). Infrared spectroscopy was carried out using the reflectance method with a resolution of 4 cm−1, a measuring range of 400–4000 cm−1, a scanning time of 64 s, and several scans of 64. The data were processed by the K-K transformation.
Raman spectroscopy analysis
The samples were analyzed for impurity mineral composition using a micro confocal Raman spectrometer (instrument model: JASCO NRS-7500). Test conditions: laser 532 nm, power attenuation sheet 100%, grating 1800nm, measurement range 100–4000 cm−1, acquisition time 20 s, accumulation times 3 times, resolution 0.9 cm−1.
Trace element analysis
Major and trace element analyses were conducted by LA-ICP-MS at the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan. Areas on each test sample where no significant soil erosion action occurred were selected for testing. Two test points were selected for each area and it was used to verify the reliability of the data.
Detailed operating conditions for the laser ablation system and the ICP-MS instrument and data reduction are the same as description by Liu et al.28. Laser sampling was performed using a GeoLas 2005. An Agilent 7500a ICP-MS instrument was used to acquire ion-signal intensities. Helium was applied as a carrier gas. Argon was used as the make-up gas and mixed with the carrier gas via a T-connector before entering the ICP. Nitrogen was added into the central gas flow (Ar+He) of the Ar plasma to decrease the detection limit and improve precision (Hu et al.)29. Each test consisted of approximately 20 s of background acquisition and 40 s of sample acquisition. The laser beam spot size was 44 μm, the laser frequency was 5 Hz, the energy was 80 mJ, and the number of laser stripping was 250 pauls. A SRM 610 was used as a quality control specimen to monitor and correct for instrument sensitivity drift. Multiple ISMs (BHVO-2G, BCR-2G, and BIR-1G) were used for multiple external standard corrections (Liu et al.)28. The preferred values of element concentrations for the USGS reference glasses are from the GeoReM database (http://georem.mpch-mainz.gwdg.de/). Off-line selection and integration of background and analyte signals, and time-drift correction and quantitative calibration were performed by ICPMSDataCal (Liu et al.28; Liu et al.)28,30.
LDA method
Linear Discriminant Analysis (LDA) is a method that uses statistics, pattern recognition, and machine learning techniques to find a linear combination of features of two classes of objects or events to characterize or distinguish between them. It is the primary tool in this classification of nephrite from dolomite-related deposits. Software utilizing IBM SPSS Statistics, version 27, was applied to this statistical analysis. Based on the trace-element concentrations collected using LA-ICP-MS, the general procedure for LDA origin determination entailed two steps. Firstly, the raw dataset of test points with known mineral occurrences and their trace element information is used as the “training set” to construct a discriminant function (DF) and determine the optimal separation. The effectiveness of this separation is evaluated using eigenvalues (EV) and total cross-validation (CV). Secondly, test samples from unknown sources, along with their trace element information, are treated as the test set21.
Test results
Infrared spectroscopy
The infrared spectra of the analyzed 30 samples exhibit standard spectral peaks of tremolite (Fig. 2). The characteristic peaks are mainly concentrated in the mid-infrared fingerprint region from 1200 to 400 cm−1, including 1139, 1071, 1046, 994, 925, 763, 688, 540, 515, 467 cm−1, of which 1139, 1071, 1046, 994, 925 cm−1 are the anti-symmetric telescopic vibration of O-Si-O and Si-O-Si and the O-Si-O symmetric stretching vibrations, 763, 688 cm−1 are Si-O-Si symmetric stretching vibrations, 540, 515, 467 cm−1 are Si-O bending vibrations and M-O lattice vibrations31.
Infrared Spectra of Jade Artifact Samples for Mineral Source Analysis from Guojiamiao Cemetery.
Raman spectroscopy
The Raman spectra of the 30 samples analyzed in this work all conform to the standard spectral peaks of tremolite (Fig. 3). The characteristic peaks are concentrated in the fingerprint frequency region from 100 to 1200 and from 3600 to 3700 cm−1 Raman shifts, including 173, 225, 370, 396, 672, 925, 1021, 1060, 3634, 3674 cm−1, in which the Raman shifts caused by the stretching vibration of M-OH are located in 3674 and 3634 cm−1, the Raman shifts caused by the stretching vibration of Si-O Raman shifts due to Si-O stretching vibrations are located at 1060, 1021, and 925 cm−1, Raman shifts due to Si-O-Si stretching vibrations are located at 672 cm−1, and Raman shifts due to M-O lattice vibrations are located at 396, 370, 225, 173 cm−1 31.
Laser Raman spectra of Jade Artifact Samples for Mineral Source Analysis from Guojiamiao Cemetery.
Geochemical characteristics
Major elements
The LA-ICP-MS test results show that the main components of jade excavated from Guojiamiao Cemetery are SiO2, MgO and CaO, of which the content of SiO2 is 58.14–61.95 wt.% (mean value 59.88 wt.%), the content of MgO is 22.67–25.08 wt.% (mean value 23.79 wt.%), and the content of CaO 13.24–15.99 wt.% (mean value 14.38 wt.%), and its content is consistent with that of dacite-type tremolite jade. 15.99 wt.% (mean value 14.38 wt.%), and its content is consistent with that of dacite-type tremolite jade.
In addition, the TFeO content of the samples ranged from 0.21 to 1.26 wt.% (mean value 0.71 wt.%), and according to the nomenclature of the hornblende group developed by the International Mineralogical Association (IMA), tremolite, actinolite, and ferrierite are classified based on the percentage of Mg 2+ and Fe 2+ per unit molecule. The classification rules for tremolite, caliche, and iron actinolite are as follows: R* (R*=Mg 2+ / (Mg 2+ +Fe 2+)) is tremolite in the range of 0.90–1.00, actinolite in the range of 0.50–0.90, and iron actinolite in the range of 0.00–0.5032. The R* range of the calculated samples is between 0.94 and 0.99, indicating that the main component of the batch of samples is tremolite.
Rare earth elements
The rare earth elements in the LA-ICP-MS test data were standardized based on the globular meteorite data proposed by Palme H (2014), and the standardized illustration of trace element globular meteorites was plotted (Fig. 4)33. The results reveal that the Guojiamiao Cemetery tremolite jade samples have a horizontal seagull-like rare earth element partitioning pattern, with total rare earth (∑REE) ranging from 0.93 to 22.64 mg/kg, with an average value of 5.26 mg/kg, the total rare earth is generally low, and its ore-forming host rock is basaltic; the ratio of light and heavy rare earth (LREE/HREE) ranges from 0.38 to 5.29, with an average value of 2.07. The ratio of light to heavy rare earth (LREE/HREE) ranges from 0.38 to 5.29, with an average value of 2.07, and the difference between light and heavy rare earth is not obvious; the europium anomaly (δEu) ranges from 0.12 to 1.67, with an average value of 0.57, which shows an obvious negative anomaly; the cerium anomaly (δCe) ranges from 0.23 to 1.11, with an average value of 0.78, which shows a slightly negative anomaly (Table 2).
Chondrite-Normalized REE Patterns of Jade Artifact Samples for Mineral Source Analysis from the Guojiamiao Cemetery.
Trace elements
Trace elements tested by LA-ICP-MS were normalized to the raw mantle trace element data published by S.-s. Sun and W.F. McDonough in 1989 and a trace element spidergram was produced34. The trace element spidergrams are an expansion of the rare earth element partitioning pattern and allow an analysis of sample deviation relative to the primitive mantle. The results show that there are obvious positive anomalies for U and negative anomalies for Ba in the trace elements of the tested samples, while there are relative enrichments of Rb and Sr in the large ionophilic elements and relative losses of Th, Zr, and Hf in the high-field-strength elements (Fig. 5).
Spider Diagram of Trace Elements in Jade Artifact Samples for Mineral Source Analysis from the Guojiamiao Cemetery.
Discussion
Jade quality
The 30 jade samples unearthed from Guojiamiao Cemetery consist entirely of tremolite. The results of tests including the infrared spectra, Raman spectra, and principal components are all consistent with the standard values. The samples of tremolite jade from Guojiamiao Cemetery can be categorized as green, greenish-white, white, sugar-colored, and sugar-white, with greenish-white being the most prevalent. Specifically, out of the samples, only GM86:104 are pure white, comprising 5 pieces of green jade, 12 pieces of greenish-white jade, 8 pieces of white jade, and 5 pieces of sugar-white jade. The tremolite jade samples exhibit a fine structure with a noticeable greasy luster. Most samples display low percolation whitening, with percolated parts showing short fibrous distributions of tremolite crystals (Fig. 6). The GM76:1 specimen displays vein-like patterns of tremolite, indicating a multi-phase formation process. The transparency of the later-formed tremolite is significantly higher than that of the earlier phases, resembling a “waterline” effect (Fig. 6C). In the tremolite jade samples from Guojiamiao Cemetery, internal impurity minerals are minimal, mostly appearing as white inclusions dispersed in a cotton-like manner, and generally devoid of graphite and other dark inclusions. However, a few samples do contain dark-colored impurity minerals along fissures, and primitive dissolution porosity filled with yellow-brown impurity minerals is observed in specimen CM17:3 (Fig. 7A).
A Due to the effect of soil burial, the crystal structure of tremolite can be seen in the jade artifacts in the form of short clusters. B The phenomenon of shedding of short needle-like inclusions is visible in jade. (C) It has a distinctive fibroblastic texture in sample GM76:1, also known in gemmology as “waterline”. D The original yellow-brown color formed by surface weathering is retained in jade GM55:06.
A Sample CM17:3 contains numerous white cottony inclusions, black graphite inclusions, and internal dissolution holes. B There is a large amount of white stony floral inclusions in sample GM74:4.
Based on the material, color, texture, and impurity mineral characteristics of the samples, the Guojiamiao Cemetery tremolite jade artifacts are of high quality.
Jade texture in burials of different grades
A total of 108 burials were excavated at Guojiamiao Cemetery from 2014 to 2015. The burials can be categorized into large-sized, medium-sized, and small-sized based on the size of the grave, the presence of a tomb passageway, the type of coffins, burial tools, and the number of unearthed artifacts. The small-sized burials can be further divided into bronze tombs and ceramic tombs. The samples analyzed in this paper come from 10 medium-sized tombs and 4 small-sized tombs. There is no obvious difference between the medium-sized tombs and the small-sized tombs in terms of the quality of the jade, according to the archaeological excavation. However, the medium-sized tombs have a significantly larger number of burials than the small-sized tombs. It’s important to note that the samples tested this time were only some of the tremolite jade objects from the medium-sized and small-sized burials (Table 3). Therefore, determining the difference in jade quality used in the Guojiamiao Cemetery requires further research.
Mineral sources
The mineral source of unearthed jade can be comprehensively analyzed in terms of its raw stone skin, raw stone skin color, impurity minerals, color, structure, major elements, rare earth elements, trace elements, and other characteristics. Among them, the first five items are manifestations of the macroscopic characteristics of the jade material, which can be used to initially judge the environment in which the jade material was formed and the crystallisation state of the jade material itself. The chemical composition characteristics of the last three points are quantitative indicators for distinguishing different mineral sources. Based on the differences in the geochemical characteristics of the jade materials, a mathematical mineral source discrimination model can be constructed to determine the mineral source of the samples.
Jade macro characteristics
The Guojiamiao Cemetery tremolite jade objects (Fig. 8D) retain a yellowish-brown skin layer from the original mineral material, and some display heavily percolated original peridot contact zones (Fig. 8B). High-quality jade (Fig. 9A) typically exhibits a primitive skin color and fine, even texture with a greasy luster formed by oxidation after being produced in the primitive strata and naturally transported to the surface or near it. The presence of primitive weathered layer and skin color is a typical feature of tremolite jade from various regions. Jades with these characteristics are formed in deep layers and then naturally transported to the surface or near-surface, where oxidation occurs. The environments in which they are found are usually dry, with some precipitation, and the northwestern region of China is particularly consistent with these conditions.
A The original weathered cortex is preserved in jade GM29:7. B, C The original peritectic contact zone, which is heavily percolated, remains at the edges of samples GM39:10-7 and GM76:34. D Sample GM83:3 shows the yellowish-brown cortex retained by the raw mineral.
A Sample GM55:06 retains a yellow cortex formed by surface weathering. B Sample GM74:1 retains a yellow cortex formed by surface weathering and a white seepage colour formed by soil burial.
Rare earth element discrimination model
Rare earth elements in minerals are often differentiated according to their mineralization environments, which can be reflected geochemically by the total amount of rare earth (∑REE), the ratio of light to heavy rare earth (LREE/HREE), and the europium and cerium anomalies (δEu) and (δCe), etc. The values of LREE/HREE and δCe are more effective in distinguishing between nephrites of different origins, which reflects the differences in the parent rocks and the geochemical properties of nephrites of different origins. The LREE/HREE and δCe values are good for distinguishing nephrites from different origins, reflecting some differences in the parent rocks, fluid sources, geochemical properties, and formation environments of different origins35.
Previous studies have shown that the major tremolite jade production areas in China can be divided into four groups according to the rare earth distribution pattern (Table 4)35. The first group includes Xinjiang, Gansu, and Qinghai, characterized by a low total rare-earth content, minimal differentiation between light and heavy rare earth elements, a horizontal seagull-shaped distribution pattern, and pronounced negative europium (Eu) anomalies. The second group comprises Luodian, Guizhou, and Dahua, Guangxi, notable for their high total rare-earth content, significant differentiation between light and heavy rare earths, a right-tilting pattern, inconspicuous Eu anomalies, and prominent negative cerium (Ce) anomalies. The third group, from Liyang, Jiangsu, is defined by low total rare-earth content, clear differentiation between light and heavy rare earths, a right-sloping distribution pattern, and negative Eu anomalies. The fourth group, from Xiuyan, Liaoning, exhibits high total rare-earth content, marked differentiation between light and heavy rare earths, a right-sloping pattern, and negative Eu anomalies.
The rare-earth element distribution patterns of the jade artifacts excavated from the Guojiamiao Cemetery indicate generally low total rare-earth content, minimal differentiation between light and heavy rare earths, and pronounced negative Eu anomalies. Based on these characteristics, it can be inferred that the metallogenic environments of these artifacts closely align with those of the first group (Xinjiang, Gansu, and Qinghai).
Trace element discrimination model
The Chinese dacite-type tremolite jade provenance discrimination model, developed by selecting a combination of multiple trace elements, offers a reliable method to trace the origin of unknown samples based on their production areas, leveraging the metallogenic patterns and geographic distribution of tremolite jade. However, since jade mining activities have evolved over time with sites being discovered and abandoned, ancient mining sources may differ from modern ones, potentially leading to inconsistencies in provenance results for certain mining areas.
To minimize such discrepancies, it is recommended to prioritize using data from mineral sources with well-defined characteristics or those located near ancient mining sites as the foundation of the reference database. In this study, trace element data were collected from seven production areas across China: Yutian in Xinjiang, Golmud in Qinghai, Maxiangshan in Gansu, Luodian in Guizhou, Dahua in Guangxi, Liyang in Jiangsu, and Xiuyan in Liaoning. By employing a stepwise tracing approach, researchers first identified the general region of origin for the sample batch and then pinpointed the specific production area. This methodology successfully clarified the source of the diorite jade material excavated from the Guojiamiao cemetery.
In the regional discrimination analysis, as shown in Fig. 10A, the tremolite jade excavated from the Guojiamiao Cemetery closely aligns with the origin characteristics of the northwest and northeast regions of China. After eliminating the more obvious differences between the southwest and southeast regions, and casting the map as shown in Fig. 10B, it becomes apparent that the samples are more closely associated with the northwest region. Further analysis of the data (Fig. 10C) reveals that the test samples from the northwest region do not correspond exactly to the individual regions of Gansu, Xinjiang, and Qinghai. There are two main reasons for this discrepancy. First, significant differences exist between ancient jade mining sites and modern mining locations. Second, the current source database is not comprehensive enough to cover all types of jade mines. As a result, it is hypothesized that the mineral material of the test samples originated from an unidentified mining site in northwestern China.
A The trace element composition of the jade artifacts found at the Guojiamiao Cemetery matches that of the northwest and northeast regions, which are two of China’s major tremolite jade-producing areas. B A statistical frequency analysis comparing the jade artifacts from Guojiamiao Cemetery with those from the northwest and northeast regions of China indicates that their trace element compositions more closely resemble those from the northwest region. C Further division of the northwest region into the Xinjiang, Gansu, and Qinghai subregions, based on mathematical discrimination results, suggests that the raw material production of the jade artifacts excavated from the Guojiamiao cemetery is in a class of its own in the Northwest China region. The attribution of these samples can be compared in a more comprehensive source characterization database in the future.
The trace element classification results for jade samples from the Guojiamiao Cemetery (Table 5) demonstrate a 100% discrimination accuracy for the three known source regions, with a cross-validation accuracy of 99.5%. In this analysis, 54.2% of the samples align more closely with the Xinjiang production area, 45.8% with the Gansu production area, and none with the Qinghai production area. These findings suggest that the trace element composition of the test samples is more consistent with those from Gansu and Xinjiang.
In conclusion, the macroscopic characteristics of the tremolite jade artifacts excavated from the Guojiamiao Cemetery, combined with the rare-earth element profiles and trace element compositions of the samples, strongly suggest that most of the jade materials used during the Guojiamiao Cemetery period originated from low-altitude regions in northwestern China.
It is well known that there were two types of jade mining in ancient times: “local” and “distant”. In the Neolithic period, many cultures in China obtained jade mainly from local sources, such as the Hongshan culture, which obtained jade from the Xiuyan region of Liaoning. During the Shang and Zhou periods, especially in the middle of the Western Zhou, the jade ritual system was gradually perfected, the demand for jade objects increased, and more attention was paid to the craftsmanship of jade forms and the quality of jade materials.
The recent discoveries of the Hanxia Jade Mining Site and the Mazongshan Jade Mining Site in Gansu confirm that large-scale jade mining activities took place in the Beishan region of Gansu during the Warring States period36,37. Evidence suggests that a jade trade route, beginning as early as the Qijia culture period around 2000 BCE, extended from Xinjiang to inland China via the Hexi Corridor38,39,40. Some scholars have proposed the existence of a “Jade Road,” supported by archaeological evidence, field studies, and experimental analyses41,42,43,44. Among the jade objects unearthed in the Zenghouyi Tomb in Hubei Province, we found jade objects with distinctive features of Gobi Desert weathering, which could only have been formed on the Gobi Desert, a sandy and wind-blown area in northwestern China. This proves that the ancestors had already begun to bring materials from far away on a large scale during the two-week period. This route not only facilitated the transportation of tremolite jade but also enabled the movement of significant quantities of turquoise and chalcopyrite jade45. Furthermore, with the establishment of this jade trade route, the exchange of materials expanded beyond jade; glass from Mesopotamia was introduced into China, marking an early instance of cultural and material exchange along the route46.
The Guojiamiao Cemetery is an aristocratic burial site dating to the late Western Zhou and early Spring and Autumn periods of the Zeng state. It holds significant historical value as a reflection of the transition from the Western Zhou to the Eastern Zhou. Archaeological evidence indicates that the Zeng state played a pivotal role in countering the territorial expansion of the Chu state during this time47. Findings from the site suggest that the Zeng state adhered closely to Zhou cultural traditions while flourishing as a regional hub known as “Hanyang Ji”48. The use of jade in funerary practices is consistent with the customs of the Zhou cultural circle. Comparing the jade objects excavated from the Zhou Yuan site, the channels for obtaining jade materials also seem to be consistent with those of the Zhou royal family. However, with the decline of the Zhou royal authority, these sources and the associated practices may have undergone gradual changes, a hypothesis that warrants further investigation.
Conclusions
The analysis of tremolite jade samples excavated from Guojiamiao reveals that they are of high quality, featuring a fine texture and largely preserving their original yellowish-brown outer surface. are commonly found in diorite jade weathered by natural environmental factors, including materials shaped by mountain water, Gobi conditions, and sub-rounded transport. Based on their color and other distinguishing traits, it is proposed that the tremolite jade likely originated from northwestern China.
The samples show a low total rare earth content, with no distinct light-heavy rare earth element differentiation but noticeable negative europium anomalies. This suggests a metallogenic environment similar to that of tremolite jade from Xinjiang, Gansu, and Qinghai. A trace element discrimination model indicates the ore source is likely in the border region between northwestern Gansu and southeastern Xinjiang.
The study suggests a stable supply of tremolite jade for Zeng State’s noble cemeteries from the late Western Zhou Dynasty to the early Spring and Autumn Period. The Zeng State’s cultural influence was dominated by Zhou culture, and its jade usage system followed Zhou rites. Understanding the source of the tremolite jade from the Guojiamiao Cemetery is crucial for exploring jade usage during the early Western Zhou to the middle Warring States period.
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