摘要
危地马拉“永楚料”翡翠是近年来中国翡翠市场上出现的新品种,其颜色多为深绿色。本文收集了4件危地马拉“永楚料”翡翠成品和1件原石样品,在常规宝石学测试的基础上,通过红外光谱、激光拉曼光谱、紫外-可见光谱和电子探针等测试技术对其化学成分、谱学特征和颜色成因等进行了分析与讨论。结果显示:危地马拉“永楚料”翡翠样品的折射率为1.66~1.67(点测),相对密度为3.33~3.34,玻璃光泽,长短波紫外光下均为荧光惰性;红外光谱表明样品的主要矿物为绿辉石,成分均匀;拉曼光谱表明样品中的绿辉石为P 2/n型结构,其他物相包括榍石和无定形碳,榍石常具“网脉状”截面;紫外-可见光谱出现437 nm和636、658、688 nm处吸收峰,分别由Fe^(3+)和Cr^(3+)所致。“永楚料”翡翠在自然光下的体色由Cr^(3+)主导,Fe^(2+)以及Fe^(2+)—Fe^(3+)间的电荷转移参与影响;电子探针计算得出“永楚料”翡翠中绿辉石的平均化学式为(Na _(0.50) Ca _(0.49))0.99(Mg_( 0.46) Fe_( 0.08) Al _(0.48) Cr_( 0.01))1.03[(Si _(1.99 )Al _(0.01))_(2) O_( 6)]。“永楚料”翡翠样品更富Mg贫Fe元素,其更高含量的Cr元素及副矿物以榍石为主的特征有别于危地马拉和缅甸墨翠。
In recent years,a new variety of Feicui(also translated as jade)named“Yongchuliao”has emerged in Chinese markets.This kind of Feicui with a dark green colour is from Guatemala.In this study,the authors collected 4 pieces of“Yongchuliao”products and 1 piece of rough stone.The conventional gemmological characteristics,chemical composition,spectral characteristics,and colour origin of the“Yongchuliao”samples have been tested,analyzed and discussed through infrared absorption spectra,laser Raman spectra,UV-Vis spectra,and electron probe micro-analysis,respectively.The results showed that the refractive index of“Yongchuliao”samples falls between 1.66-1.67(point measurement),with a specific gravity of 3.33-3.34,presenting a glass luster and inert fluorescence under both long wave and short wave ultraviolet light.Infrared spectra revealed that the main mineral of the“Yongchuliao”samples are omphacite,and the composition of omphacite has remarkable consistency.Raman spectra showed that the crystal structure of this type of omphacite is P 2/n,and other phases in“Yongchuliao”samples include titanite and amorphous carbon.Moreover,titanite often has a“reticulated cross”section.UV-Vis spectra exhibited characteristic peaks at 437 nm(caused by Fe^(3+)),and 636,658,688 nm(caused by Cr^(3+)).And the colour of“Yongchuliao”under natural light is primarily influenced by Cr^(3+)and is also affected by both Fe^(2+)and the charge transfer between Fe^(2+)and Fe^(3+).The average chemical formula of“Yongchuliao”according to the results of electron probe micro-analysis is(Na _(0.50) Ca _(0.49))0.99(Mg_( 0.46) Fe_( 0.08) Al _(0.48) Cr_( 0.01))1.03[(Si _(1.99 )Al _(0.01))_(2) O_( 6)].In addition,“Yongchuliao”is richer in Mg and poorer in Fe.A higher content of Cr makes it distinguishable from Guatemalan Mocui.“Yongchuliao”with only titanite as its accessory mineral is also different from Mocui from Myanmar and Guatemala.
作者
徐世龙
杨九昌
陈全莉
XU Shilong;YANG Jiuchang;CHEN Quanli(Gemmological Institute,China University of Geosciences,Wuhan 430074,China;Hubei Gems and Tewelry Engineering Technology Research Center,Wuhan 430074,China;The School of Jewelry,West Yunnan University of Applied Sciences,Baoshan 679118,China)
基金
中国地质大学(武汉)珠宝学院开放基金(CIGTXM-04-S202305)
云南省本科教育教学改革研究项目(JG2023143)。
关键词
“永楚料”翡翠
绿辉石
宝石学特征
危地马拉
“Yongchuliao”Feicui(jade)
omphacite
gemmological characteristic
Guatemala
