Mineralogy and Geochemistry Characteristics of Nephrite from Jingbaoer Grassland Jade Mine Site in Mazongshan Town, Gansu Province, China: Implications for the Provenance of Excavated Jade Artifacts

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Detalles Bibliográficos
Publicado en:	Minerals vol. 15, no. 11 (2025), p. 1186-1210
Autor principal:	Liu Jifu
Otros Autores:	Cao, Yi, Chang, Yuan, Su, Yue, Yu, Xuan, Yang, Mingxing
Publicado:	MDPI AG
Materias:	Gansu China South Korea United States > US China Mass spectrometry Aluminum oxide Silurian Scanning electron microscopy Manganese Grasslands Apatite Devonian Polarized light Scientific imaging Refractivity Mining Diopside Optical microscopy Ancient civilizations Electron microscopy Comparative analysis Rutile Silica Lasers Mineralogy Geochemistry Precambrian Relative density Mass spectroscopy Light microscopy Chlorite Marble Tremolite Cultural heritage Provenance Silicon dioxide Inclusions Inductively coupled plasma mass spectrometry Artifacts Chemical elements Specific gravity Electron probe microanalysis Laser ablation Recrystallization Chinese history Geology Electron probe Refractive index Titanite Saccharides Archaeology Ablation Calcium magnesium silicates
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Descripción
Resumen:	The Jingbaoer Grassland Jade Mine situated approximately 20 km northwest of Mazongshan Town in Gansu Province, China, represents an important source of nephrite dating back to the pre-Qin period. In this study, 58 representative nephrite samples were analyzed to investigate their mineralogical and geochemical characteristics using polarized light microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The mine is situated near the contact zone between the Silurian Gongpoquan Group and Devonian granite, with surrounding rocks primarily consisting of Precambrian dolomitic marble. The nephrite displays diverse colors—white, bluish-white, sugar-white, and cyan—with darker tones and abundant manganese-stained dendritic and flocculent inclusions. It shows a relative density of 2.82–2.99, a refractive index of 1.60–1.62, and a vitreous to greasy luster. Texturally, the jade is predominantly composed of micro-fibrous interwoven tremolite, occasionally exhibiting oriented recrystallization textures. Minor minerals include diopside, apatite, titanite, chlorite, epidote, allanite, rutile, and graphite. Chemically, the samples are rich in SiO2, MgO, and CaO, with trace amounts of FeO, MnO, Al2O3, and Na2O. Notably, Sr and Sm are enriched, Nb is slightly depleted, and Eu shows a distinct negative anomaly. The average total rare earth content is 4.25 µg/g. The study suggests that the deposits in the research area are typical of the contact-metasomatic type, formed through multi-stage hydrothermal metasomatism between acidic granitic intrusions and dolomitic marble, creating favorable conditions for the formation of high-quality tremolite jade. Comparative analysis with jade artifacts excavated from the Tomb of Marquis Yi of Zeng suggests a possible provenance link to the Jingbaoer deposit, providing valuable evidence for the historical mining and distribution of nephrite during the Warring States period.
ISSN:	2075-163X
DOI:	10.3390/min15111186
Fuente:	ABI/INFORM Global