Gemmological Characteristic of "Tanghe Jade" and Its Quality Evaluation
-
摘要:
“唐河玉”主要产于太行山北端的唐河流域,在拒马河、易水河也有少量产出,该玉石的“籽料”主要由透闪石构成,颜色以白色、黄色、红色和黑色为主,偶尔伴有灰色、青色和绿色等次要色调。然而,杂质矿物的存在导致了该玉石质量呈现出一定程度的差异性。为了深入研究这一现象,本研究采取了实地勘查和市场调研相结合的方法,对采集到的“山料”及“籽料”样品进行了系统的宝石矿物学特征分析。在传统宝玉石研究方法的基础上(如折射率、相对密度、硬度以及显微观察和红外光谱分析),本研究综合应用了现代分析技术,包括X射线衍射分析、电子探针分析和扫描电子显微镜镜分析,全面深入地探究“唐河玉”样品的矿物和结构组成。研究结果显示,“唐河玉”样品的折射率为1.56~1.61(点测法),相对密度2.85~3.07,摩氏硬度6~7,表现出良好的油润度和宏观上的蜡状至油脂光泽。在偏光显微镜下观察,其主要矿物组成为透闪石,同时伴有碳酸盐矿物、石英、透辉石等杂质矿物。其中,透闪石呈柱状和纤维状变晶结构,其中纤维状变晶的纤维长度约为0.01~0.10 mm,交织形成复杂的微观纹理;而柱状变晶的粒度则在0.05×0.02 mm至1.00×0.15 mm,颗粒相互镶嵌,且杂质矿物不均匀地分布在纤维状透闪石之间。通过扫描电镜的二次电子成像技术有效地揭示了“唐河玉”样品中矿物颗粒的大小、形态和结晶程度。观察结果表明,部分透闪石颗粒以纤维放射状分布且相互交织,在小区域范围内的定向排列。这些颗粒之间排列紧密,部分显示出显微纤维交织结构。在局部范围内,纤维状的透闪石呈现出规则的排列,颗粒间交织紧密。整体上,规则排列的透闪石在非定向的穿插中形成整体结构,颗粒表面光滑平整,少数颗粒表面具有纵向纹理。此外,部分透闪石颗粒呈现出略具定向的分布特征,聚集形成宽窄不一的条带状集合体。石英颗粒则以自形-半自形的粒状形态穿插于透闪石之中,粒度大约为5 μm。结合电子探针分析和X射线粉末衍射测试结果显示“唐河玉”样品的主要矿物组成为透闪石,次要矿物有方解石、石英和透辉石。在钙质角闪石系列中,透闪石-阳起石的“唐河玉”样品Mg/(Mg+Fe2+)比值大于0.98,接近于透闪石端元的理论值1.0。“唐河玉”样品的红外光谱与透闪石的标准光谱峰位基本一致,主要表现在600~400 cm-1、800~600 cm-1、1 200~800 cm-1、3 750~3 600 cm-1等四个波段。其中,1 147、1 063、1 042、996、922 cm-1附近的尖锐吸收峰归因于Si-O-Si的反对称伸缩振动、O-Si-O的对称伸缩振动和反对称伸缩振动所致。而765、687、665、644 cm-1的吸收峰则是由Si-O-Si的对称伸缩振动引起。546、514、459、420 cm-1的吸收峰则由Si-O的弯曲振动及M-O的晶格振动造成。此外,在1 560~1 400 cm-1波段,部分样品显示出不同强度的吸收,这归因于碳酸盐矿物晶体结构中[CO3]2-的反对称伸缩振动和面外弯曲振动引起。基于上述研究成果,建立了以碳酸盐矿物质量分数为依据的“唐河玉”宝石学命名标准,具体分类如下:当碳酸盐矿物质量分数低于5%,且透闪石质量分数不低于95%时,命名为“透闪石玉”;当碳酸盐矿物质量分数在5%~40%,且透闪石质量分数在60%以上时,命名为“方解石-透闪石玉”或“白云石-透闪石玉”;当碳酸盐矿物质量分数不低于50%,且透闪石质量分数低于40%时,命名为“透闪石化大理岩”。鉴于“唐河玉”具有独特的“草花”纹理特征及其颜色、纹理和质地的丰富多样性,本研究将这些特性与“籽料”属性和唐尧文化进行了综合评估。在此基础上,通过宣传其深厚的文化和独特的美学价值,并依据玉石的品质进行市场定位,为“唐河玉”的进一步开发和应用提供了清晰的发展方向。
Abstract:"Tanghe jade", predominantly harvested from the Tanghe River basin in the northern Taihang Mountain range, is also output in modest quantities along the Juma and Yishui rivers. The primary colours of "Tanghe jade" are white, yellow, red, and black, complemented by secondary colours of gray, cyan, and green. The main mineral component of "Tanghe jade" is tremolite, however, the presence of impurity minerals lead to differences for its quality. In this paper, the methods of combining field investigation and market surveys, the gemmological and mineralogical characteristics of the"Tanghe jade"samples were analysed using conventional gemmological tests (eg.refractive index, relative density, hardness, microscopic observation and infrared spectroscopy), as well as XRD, EPMA, and SEM.The results show that the refractive index of "Tanghe jade" sample is 1.56 to 1.61 and the relative density is 2.85 to 3.07, while the Mohs hardness is between 6 and 7. The "Tanghe jade" is of moderate greasy luster, with wax-oily luster. Polarizing microscope observation results reveal that the predominant mineral component is tremolite, accompanied by impurities such as carbonates, quartz, and diopside. Tremolite exhibits a columnar-fibrous metamorphic texture, with some areas presenting a fibrous metamorphic structure. The fibers are mainly within the confines of 0.01-0.10 mm in length, intricately interlaced to create a tightly woven texture. Some samples exhibit columnar crystals, with grain sizes ranging from 0.05×0.02 mm to 1.00×0.15 mm. These crystals are intricately interlocked, creating a tessellated arrangement, and a minor concentration of impurity minerals is unevenly dispersed throughout the fibrous tremolite matrix.SEM results show that some tremolite particles are distributed in a fibrous, radiating pattern and interwoven together, exhibiting a directional arrangement within small areas. The particles are closely packed, with some displaying a micro-fibrous interlocking structure. Within localized domains, the fibrous tremolite is regularly arranged with closely interwoven particles. Over the entire area, the regularly arranged tremolite particles are interspersed in a non-directional manner. The surface of the tremolite particles is relatively smooth and flat, with a minority of particles exhibiting longitudinal textures. Furthermore, some tremolite particles exhibit the slightly directional distribution, aggregating into bands of varying widths to form collective aggregates. Quartz particles being automorphic form and semiautomorphic form, are interspersed in tremolite, with a particle size of approximately 5 μm. The EMPA and XRD results confirms that tremolite is the predominant mineral of "Tanghe jade", and subordinate minerals encompass calcite, quartz, and diopside. In the context of the tremolite-actinolite series within the calcic amphiboles, the sample's Mg/(Mg+Fe2+) ratio surpasses 0.98, converging on the theoretical end-member value of 1.0 for pure tremolite.The infrared spectra of "Tanghe jade" are basically consistent with standard spectral peaks of tremolite, mainly in 600-400 cm-1, 800-600 cm-1, 1 200-800 cm-1, and 3 750-3 600 cm-1. The distinct and sharp absorption bands near 1 147, 1 063, 1 042, 996 cm-1 and 922 cm-1 correspond to the antisymmetric stretching vibrations of the Si-O-Si linkages, as well as the symmetric and antisymmetric stretching vibrations of the O-Si-O bridges. The peaks at 765, 687, 665 cm-1 and 644 cm-1 indicate the symmetric stretching vibrations associated with Si-O-Si. Furthermore, the vibrations at 546, 514, 459, 420 cm-1 are attributed to the bending vibrations of Si-O bonds and the lattice vibrations involving M-O.Additionally, some "Tanghe jade"samples exhibit variable intensity absorptions in the 1 560-1 400 cm-1, which are caused by the antisymmetric stretching and out-of-plane bending vibrations of the carbonate [CO3]2- groups within the mineral's crystalline framework. Based on the above research, the gemmological designation criteria for "Tanghe jade" are established, differentiated by the mass fraction of carbonate minerals. The classification is as follows: (1) when the carbonate mineral mass fraction is below 5% and the tremolite mass fraction exceeds 95%, the material is aptly designated as "tremolite jade"; (2) when the carbonate mineral mass fraction ranging from 5% to 40% and tremolite mass fraction above 60%, the nomenclature is differentiated based on the carbonate composition as either "calcite-tremolite jade" or "dolomite-tremolite jade"; (3) when the carbonate mineral mass fraction reaches or exceeds 50% and the tremolite mass fraction falls below 40%, the material is termed "tremolite marble". By highlighting the distinctive of the pattern floral of "Tanghe jade", along with its vibrant colour palette and diverse textures, and integrating the cultural significance of the "pebbles"with the legacy of the Tang Yao civilization, the targeted promotion and quality-based market positioning of "Tanghe jade" can be strategically directed towards its enhanced development and utilization potential.
-
Keywords:
- "Tanghe jade" /
- tremolite /
- gemmological characteristic /
- quality evaluation
-
表 1 “唐河玉”透闪石的电子探针分析数据Table 1. Data of tremolite in "Tanghe jade" samples by EPMA
wB/% 成分 THY-1-1 THY-15-2 THY-23-3 THY-63-1 THY-71-4 THY-103-3 THY-104-1 SiO2 59.067 58.765 59.095 58.066 58.253 59.624 59.236 Al2O3 0.087 0.103 - 0.741 0.253 0.006 0.556 TiO2 0.036 0.007 0.014 0.065 - - 0.012 FeO 0.296 0.123 0.095 0.427 0.293 0.505 0.474 MnO 0.039 0.004 - - - - 0.023 MgO 24.900 24.774 24.705 23.925 24.562 24.933 24.344 CaO 12.491 13.273 13.463 13.343 12.727 13.299 13.504 Na2O 0.035 0.066 0.005 0.052 0.054 0.017 0.082 K2O 0.034 0.014 0.022 0.002 0.004 0.014 0.011 P2O5 - - 0.003 0.016 0.016 0.008 0.017 Cr2O3 0.222 0.253 - 0.080 0.032 - 0.019 CO2 - - - - - - - Total 97.207 97.382 97.402 96.717 96.194 98.406 98.278 Mg/(Mg+Fe2+) 98.83 99.51 99.62 98.25 98.82 98.01 98.09 矿物组成 透闪石 透闪石 透闪石 透闪石 透闪石 透闪石 透闪石 注:“-”表示该成分低于检测限 -
表 1 “唐河玉”透闪石的电子探针分析数据
Table 1 Data of tremolite in "Tanghe jade" samples by EPMA
wB/% 成分 THY-1-1 THY-15-2 THY-23-3 THY-63-1 THY-71-4 THY-103-3 THY-104-1 SiO2 59.067 58.765 59.095 58.066 58.253 59.624 59.236 Al2O3 0.087 0.103 - 0.741 0.253 0.006 0.556 TiO2 0.036 0.007 0.014 0.065 - - 0.012 FeO 0.296 0.123 0.095 0.427 0.293 0.505 0.474 MnO 0.039 0.004 - - - - 0.023 MgO 24.900 24.774 24.705 23.925 24.562 24.933 24.344 CaO 12.491 13.273 13.463 13.343 12.727 13.299 13.504 Na2O 0.035 0.066 0.005 0.052 0.054 0.017 0.082 K2O 0.034 0.014 0.022 0.002 0.004 0.014 0.011 P2O5 - - 0.003 0.016 0.016 0.008 0.017 Cr2O3 0.222 0.253 - 0.080 0.032 - 0.019 CO2 - - - - - - - Total 97.207 97.382 97.402 96.717 96.194 98.406 98.278 Mg/(Mg+Fe2+) 98.83 99.51 99.62 98.25 98.82 98.01 98.09 矿物组成 透闪石 透闪石 透闪石 透闪石 透闪石 透闪石 透闪石 注:“-”表示该成分低于检测限 -
[1] 刘长跃. 唐河彩玉的特色及开发前景[J]. 宝藏, 2016(6): 116-118. Liu C Y. Characteristics and development prospect of "Tanghe colored jade"[J]. Treasure, 2016(6): 116-118. (in Chinese)
[2] 康志娟, 韦金玉, 雷玮琰, 等. "唐河玉"的宝石学特征[J]. 宝石和宝石学杂志(中英文), 2019, 21(6): 50-57. doi: 10.15964/j.cnki.027jgg.2019.06.006 Kang Z J, Wei J Y, Lei W Y, et al. Gemmological characteristic of "Tanghe jade"[J]. Journal of Gems & Gemmology, 2019, 21(6): 50-57. (in Chinese) doi: 10.15964/j.cnki.027jgg.2019.06.006
[3] 王濮, 潘兆橹, 翁玲宝, 等. 系统矿物学[M]. 北京: 地质出版社, 1987: 196-198. Wang P, Pan Z L, Weng L B, et al. Systematic mineralogy[M]. Beijing: Geology Press, 1987: 196-198. (in Chinese)
[4] 陈呈, 於晓晋, 王时麒. 河北唐河彩玉石的矿物学特征及其鉴定方法的研究[J]. 岩石矿物学杂志, 2014, 33(S1): 89-96. Chen C, Yu X J, Wang S Q. Study on mineral composition and identification methods of Tanghe colored jade in Hebei Province[J]. Acta Petrologica et Mineralogica, 2014, 33(S1): 89-96. (in Chinese)
[5] 康志娟, 邢琳, 张欣, 等. 河北涞源绿色透闪石质玉宝石学特征[C]// 2023中国国际珠宝首饰学术交流会论文集. 北京: 中国宝石, 2023: 218-221. Kang Z J, Xing L, Zhang X, et al. Mineralogical characteristics of nephrite from Laiyuan County, Hebei, China[C]//2023 China Gems & Jewelry Academic Conference. Beijing: China Gems, 2023: 218-221. (in Chinese)
[6] 陈呈, 於晓晋, 王时麒. 河北唐河透闪石玉的宝石学特征及矿床成因[J]. 宝石和宝石学杂志(中英文), 2014, 16(3): 1-11. https://jogg.cug.edu.cn/article/id/f8211854-25e0-49e7-a5f0-f43e8463f14d Chen C, Yu X J, Wang S Q. Study on gemmological characteristics and ore genesis of nephrite from Tanghe, Hebei Province[J]. Journal of Gems & Gemmology, 2014, 16(3): 1-11. (in Chinese) https://jogg.cug.edu.cn/article/id/f8211854-25e0-49e7-a5f0-f43e8463f14d
[7] 张勇, 冯晓燕, 陆太进. 透闪石质玉石的副矿物组成及其对定名的影响[C]// 2017中国国际珠宝首饰学术交流会论文集. 北京: 中国宝石, 2017: 189-195. Zhang Y, Feng X Y, Lu T J. The accessory minerals of tremolite jade and their impact on the naming[C]//2017 China Gems & Jewelry Academic Conference. Beijing: China Gems, 2017: 189-195. (in Chinese)
[8] 廖宗廷, 钟倩, 支颖雪, 等. 贵州和田玉的产地标性特征和鉴别初探[J]. 宝石和宝石学杂志(中英文), 2018, 20(S1): 54-64. Liao Z T, Zhong Q, Zhi Y X, et al. Origin characteristic and identification of nephrite from Luodian, Guizhou Province[J]. Journal of Gems & Gemmology, 2018, 20(S1): 54-64. (in Chinese)
[9] 刘奕岑, 周征宇, 杨萧亦, 等. 透闪石质玉中黄玉与糖玉致色成因差异研究[J]. 岩石矿物学杂志, 2021, 40(6): 1 189-1 196. Liu Y C, Zhou Z Y, Yang X Y, et al. Study on difference of color genesis between yellow and brown tremolite jade[J]. Acta Petrologica et Mineralogica, 2021, 40(6): 1 189-1 196. (in Chinese)
[10] 王成博, 袁心强, 雷婷, 等. 新疆"直闪石玉"的宝石学特征[J]. 宝石和宝石学杂志(中英文), 2018, 20(1): 37-45. doi: 10.15964/j.cnki.027jgg.2018.01.004 Wang C B, Yuan X Q, Lei T, et al. Gemmological characteristic of "anthophyllite jade" from Xinjiang, China[J]. Journal of Gems & Gemmology, 2018, 20(1): 37-45. (in Chinese) doi: 10.15964/j.cnki.027jgg.2018.01.004
[11] 何琰, 苏越, 杨明星, 新疆于田和田玉的谱学特征及产地特征研究[J]. 光谱学与光谱分析, 2022, 42(12): 3 851-3 857. He Y, Su Y, Yang M X. Study on spectroscopy and locality characteristics of the nephrites in Yutian, Xinjiang[J]. Spectroscopy and Spectral Analysis, 2022, 42(12): 3 851-3 857. (in Chinese)
[12] 苏越, 杨明星, 王园园, 等, 中国南疆和田玉戈壁料的宝石学特征[J]. 宝石和宝石学杂志(中英文), 2019, 21(4): 1-10. doi: 10.15964/j.cnki.027jgg.2019.04.001 Su Y, Yang M X, Wang Y Y, et al. Gemmological characteristic of gobi nephrite from Southern Xinjiang, China[J]. Journal of Gems & Gemmology, 2019, 21(4): 1-10. (in Chinese) doi: 10.15964/j.cnki.027jgg.2019.04.001
[13] 钟倩, 廖宗廷, 周征宇, 等. 贵州罗甸和田玉基本特征与开发利用[J]. 宝石和宝石学杂志(中英文), 2019, 21(1): 40-48. doi: 10.15964/j.cnki.027jgg.2019.01.005 Zhong Q, Liao Z T, Zhou Z Y, et al. Characteristic, development and utilization of nephrite from Luodian, Guizhou Province[J]. Journal of Gems & Gemmology, 2019, 21(1): 40-48. (in Chinese) doi: 10.15964/j.cnki.027jgg.2019.01.005
[14] 侯冶华, 叶鹏, 曾少乾, 等. 临武透闪石玉原石质量等级划分体系初探[J]. 湖南有色金属, 2021, 37(6): 79-82. Hou Y H, Ye P, Zeng S Q, et al. Preliminary exploration on quality grading system of Linwu tremolite jade[J]. Hunan Nonferrous Metals, 2021, 37(6): 79-82. (in Chinese)