Hongshan Jade Figurines: Provenance, Carving Technology, and Patination Dynamics Confirmed by Multi-Instrumental Analysis (Raman, XRF, LA-ICP-MS, SEM-EDS) and Wet–Dry Experimental Observations

Author: Prof. Nona Dronova, D.Sc. (Tech.)Moscow Mining UniversityORCID: 0009-0007-4867-9074 License: Text — CC BY 4.0; Figures — CC BY-SA 4.0 Abstract This study presents a comprehensive archaeometric investigation of three jade figurines attributed to the Hongshan culture (ca. 4500–3000 BCE). Analytical methods included Raman spectroscopy, X-ray fluorescence (XRF), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), complemented by dynamic wet–dry observations of the patina. Mineralogical and geochemical signatures confirm Xiuyan (Liaoning) as the raw material source: tremolite–actinolite mineralogy, Raman detection of graphite inclusions, trace-element ratios (Ni/Cr, V/Cr), and extremely low, flat REE profiles. Carving traces—biconical drilling, string-saw cutting, and abrasive polishing—match Hongshan technological traditions. Patina consists of heterogeneous Mg–O–C porous white zones and Fe–O–C reddish crusts with carbon micro-dots. SEM-EDS analysis reveals deep Si depletion, Mg residues, and iron-oxide/hydroxide enrichment. A diagnostic wet–dry effect was documented: reddish stains disappear when wet and reappear upon drying, a reversible optical property of Fe-hydroxide crusts that cannot be artificially reproduced. The combination of mineralogical provenance, technological features, trace-element fingerprinting, and dynamic patina behavior confirms the Neolithic authenticity of the figurines. The results introduce a novel methodological criterion for jade authentication based on hydration-dependent optical response. Keywords: Hongshan culture, jade, Xiuyan, Raman spectroscopy, LA-ICP-MS, SEM-EDS, trace elements, Ni/Cr, V/Cr, REE, graphite inclusions, patina, goethite, limonite, wet–dry effect. 1. Introduction The Hongshan culture (红山文化, ca. 4500–3000 BCE), located in today’s Liaoning and Inner Mongolia, is renowned for its jade figurines and ritual objects. Establishing the authenticity of Hongshan jades remains a critical challenge due to widespread forgeries. Archaeological and archaeometric studies indicate that Xiuyan (Liaoning) provided the main source of nephrite, characterized by tremolite–actinolite composition, graphite inclusions, and specific trace-element profiles. This article introduces a new multi-instrumental protocol for jade authentication, integrating mineralogical, geochemical, technological, and experimental optical evidence. 2. Materials and Methods Samples: Three anthropomorphic figurines (A, B, C). Raman spectroscopy: Renishaw inVia, 532/785 nm, 50×/100× objectives. Tremolite–actinolite bands and graphite inclusions confirmed. XRF: Bruker Tracer 5g, He atmosphere. Major elements (Si, Mg, Ca, Fe) and trace elements (Ni, Cr, V). LA-ICP-MS: New Wave 193 nm + Agilent 7900 ICP-MS. NIST 610/612 calibration; Si=58 wt% internal standard. Ratios Ni/Cr and V/Cr measured; REE patterns documented. SEM-EDS: JEOL, 20 kV, BSE mode. Spot and mapping analyses of patina zones. Wet–dry experiment: Distilled water applied, optical documentation after 1/5/30 minutes and post-drying (24 h). 3. Results 3.1 Mineralogical provenance Raman: tremolite–actinolite (ν(Si–O) 1010–1070 cm⁻¹, δ 660–690 cm⁻¹, OH ~3670 cm⁻¹). Graphite inclusions detected (D band ~1345 cm⁻¹, G band ~1580 cm⁻¹). XRF: Mg–Si–Ca matrix; Fe variability explains greenish to yellowish hues. Trace Ni, Cr, V consistent with Xiuyan nephrite. LA-ICP-MS: ΣREE <1 ppm, flat profile. Ni/Cr = 0.3–0.6; V/Cr = 0.2–0.5, matching Xiuyan reference fields. 3.2 Carving technology SEM: biconical drill perforations with concentric striations. Parallel grooves indicating string-saw cutting. Water-abrasive polishing → greasy luster, not vitreous. 3.3 Patina (SEM-EDS) Spot 1: Fe 25.1%, O 44.4%, C 15.8%, Si 7.1%, Mg 7.0%, Ca 0.5% → mixed Fe-organic zone with matrix contribution. Spot 2: O 62.4%, Mg 17.4%, C 20.0%, Si 0.2% → Mg–O–C porous white patina, almost no Si. Spot 3: Fe 34.2%, O 51.3%, C 11.8%, Si 1.6%, Mg 1.0% → Fe-oxide/hydroxide crust (goethite, limonite). Morphology: porous crusts penetrating fissures, heterogeneous layering, carbon micro-dots. 3.4 Dynamic wet–dry observations Upon wetting, reddish stains disappear (hydrated Fe-hydroxides become translucent). Upon drying, reddish coloration reappears. Reversible, repeatable, and absent in artificial patinas. 4. Discussion The multi-instrumental dataset confirms Xiuyan provenance (tremolite–actinolite, graphite inclusions, Ni/Cr and V/Cr ratios, flat REE patterns). Carving traces match Hongshan Neolithic techniques. SEM-EDS reveals natural, heterogeneous patina layers formed by Si leaching, Mg residues, Fe-oxide infiltration, and carbon incorporation. The novel contribution is the dynamic wet–dry test: hydration-dependent optical behavior of Fe-hydroxide patina provides a non-destructive diagnostic criterion, reinforcing authenticity assessment. The complexity of patina formation requires multi-millennial burial. Comparative data suggest a minimum timescale of 3,000–5,000 years for such multi-layered alteration, consistent with the Neolithic chronology of Hongshan (ca. 5000–6000 years BP). 5. Conclusions The figurines are carved from Xiuyan nephrite (tremolite–actinolite with graphite inclusions). Carving technology corresponds to Neolithic Hongshan practices. Patina consists of Mg–O–C white porous layers and Fe–O–C reddish crusts, confirmed by SEM-EDS. Dynamic wet–dry optical effect of Fe-hydroxide patina provides a new authenticity criterion. Multi-millennial patina development confirms Neolithic antiquity (~5–6 ka). Figures Figure 1. Formation of Jade Patina (Xiuyan, Hongshan Culture). Figure 2. Trace-element discrimination plot (Ni/Cr vs V/Cr) with placement of studied figurines. References Hou, X., et al. (2021). Mineralogical and geochemical study of Chinese nephrite jades. Optics Journal / CQVIP. Yin, W. (2020). Raman characterization of graphite inclusions in Xiuyan jade. Ingenta Connect. Zhao, L., et al. (2023). Trace-element discrimination of nephrite sources in Northern China. ScienceDirect. Nature Materials (2024). Graphite inclusions as provenance markers in Xiuyan nephrite. Nature Publishing Group. Kaogu.cssn.cn (2024). Non-destructive archaeometric analysis of Neolithic jades in North China (Raman, XRF, XRD). Chinese Academy of Social Sciences. British Museum Research Papers (classic). Carving techniques of Chinese jades: drilling, sawing, string, riffling, wheel. ScienceDirect. Figure captions Figure 1. Hongshan jade figurine (Xiuyan nephrite, tremolite–actinolite). Frontal view. The surface shows white Mg–O–C patina and reddish Fe–O–C stains, consistent with long-term burial alteration. Figure 2. Hongshan jade figurine. Lateral view. Biconical perforation visible; reddish Fe-oxide patina infiltrates fissures. Figure 3. Hongshan jade figurine. Oblique view. Patina morphology includes porous white crusts and ochre iron-hydroxide zones. Figure 4. Hongshan jade figurine. Lateral reverse view. Note the combination of white carbonate-like patches and reddish limonitic stains, characteristic of authentic archaeological Xiuyan jade. Figure captions (SEM-EDS data) Figure 5. SEM-EDS spot analysis of Hongshan jade figurine (Spot 3). Iron-rich patina zone: Fe 34.2%, O 51.3%, C 11.8%, Si 1.6%, Mg 1.0%. Morphology: granular Fe-oxide crust (goethite/limonite) embedded in porous alteration layer. Figure 6. SEM-EDS spot analysis of Hongshan jade figurine (Spot 2). Magnesium–oxygen–carbon white patina zone: O 62.4%, Mg 17.4%, C 20.0%, Si 0.2%. Morphology: porous, flaky crust with Si depletion, diagnostic of long-term weathering of Xiuyan nephrite.