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2. Mineralogy and Geochemical Characteristics of Scheelite Deposit at Xuebaoding in Pingwu, Sichuan Province, China.
- Author
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Cao, Qinyuan, Shi, Miao, Yuan, Ye, Ma, Shiyu, and Lu, Haoyu
- Subjects
LASER ablation inductively coupled plasma mass spectrometry ,GEMS & precious stones ,RARE earth metals ,SCHEELITE ,ORE genesis (Mineralogy) ,MINERALOGY - Abstract
Featuring subtle lithological alterations in the host rocks and containing colossal gemstone crystals, the scheelite deposit at Xuebaoding in the Pingwu region of Sichuan Province exhibits characteristics typical of a vein-like hydrothermal-type deposit. The scheelite from the Xuebaoding region is renowned for its high saturation of color, perfect crystal shape, and pure color. In this study, its crystal structure and mineralogical, geochemical, and in situ Sr-Nd isotope characteristics are all systematically characterized. Our objective is to determine the source of ore-forming materials, the timing of the mineralization, and the chemical composition of scheelite, including major elements, trace elements, and rare earths elements (REE). The scheelite samples were analyzed with a variety of methods such as polarizing microscopy, X-ray powder diffraction (XRD), X-ray fluorescence spectrometry (XRF), electron probing, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In addition, conventional gemological tests were performed using instruments including gemstone microscopes, GI-UVB ultraviolet fluorescent lamps, grating spectroscopy, etc. The results demonstrate that scheelite exhibits a high refractive index, excellent crystallinity, and a granular structure. Clear color bands and ring structures are observed within the minerals, accompanied by interference colors of light blue, blue, and yellow. Additionally, the mineral components are relatively concentrated, with muscovite and illite serving as accessory minerals. Furthermore, the chemical composition of scheelite reveals a WO
3 /CaO mass ratio that approaches or exceeds the ideal value. Moreover, it exhibits a wide range of variations in total rare earth element (∑REE) content, which is characterized by an enrichment of light rare earths (LREE), significant negative Eu anomalies, and insignificant Ce anomalies. In addition, the metallogenic formation of scheelite can be estimated to have occurred during the Toarcian stage in the Lower Jurassic Epoch period, approximately 183 Ma. The study further revealed that A-type granite serves as the genesis type of scheelite, with most of the ore-forming materials originating from the upper crust and a few derived from younger crustal sources. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
3. Overview of Gemstone Resources in China.
- Author
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Yu, Xiao-Yan, Long, Zheng-Yu, Zhang, Yi, Qin, Li-Jie, Zhang, Cun, Xie, Zhi-Rong, Wu, Yu-Rui, Yan, Ying, Wu, Ming-Ke, and Wan, Jia-Xin
- Subjects
GEMS & precious stones ,IRON ores ,SPODUMENE ,MALACHITE ,GARNET ,TOURMALINE ,ZIRCON ,ORE deposits - Abstract
Gemstones are minerals of gem qualities used for adornment and decoration with the attributes of beauty, durability and rarity. Traditionally, although China has been regarded as the most important source for nephrite, over the past decades, a large variety of gemstone resources have been newly discovered in China owing to continuous exploration works. The vast land with various geological and geochemical backgrounds is rich in gemstone resources with potential for new deposits discoveries. In pegmatites, gemstones are related to granitic magma events and mainly occur in pegmatitic cavities, such as tourmaline, aquamarine, spodumene, spessartine, moonstone, quartz, apatite, and topaz. The eruption of Tertiary basaltic magma provides gem-quality sapphire, spinel, olivine, garnet, and zircon. The supergene oxidation zones of some copper and iron deposits in Hubei and Anhui province host gem-quality turquoise and malachite. Moreover, the formation of the nephrite deposit in China is mostly related to the carbonatite and serpentinite rocks involved in the metamorphic-metasomatic processes. This paper comprehensively introduces the distribution of gemstones deposits, as well as the gemological and mineralogical characteristics of gemstones in China. Our present investigation provides insights into the gemstone potential of China for further exploitation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
4. Turquoise Ornaments and Inlay Technology in Ancient China.
- Author
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QIN XIAOLI
- Subjects
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TURQUOISE jewelry , *GEMS & precious stones , *NEOLITHIC Period , *PENDANTS (Jewelry) , *COMPOSITE materials ,DESIGN & construction - Abstract
Most turquoise objects from early Neolithic sites in China are pendants made of a single material. From the later Neolithic period, however, people started to create turquoise ornaments with two or more composite materials. Ornaments were inlaid with turquoise and other materials using new techniques. In the Early Bronze Age, the turquoise production process reached its peak. At the Erlitou site, archaeologists found a large dragon-shaped turquoise mosaic, a variety of animal-shaped turquoise decorations, and turquoise workshops. The purpose of this paper is to understand the importance of turquoise products in the formation process of early state formation in China by analyzing the following topics: the technological evolution of turquoise manufacture, the combination of composite materials, the use of adhesive in turquoise inlay, and the associated production processes as they developed from the Neolithic to Early Bronze Age. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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