三种黑曜岩的宝石学特征及光学现象成因探讨  

Gemological characteristics and genesis of optical phenomena of three types of obsidian rocks

作　　者：刘嘉钧 阮青锋[1] 邱川 罗洁 LIU Jiajun;RUAN Qingfeng;QIU Chuan;LUO Jie(l.college of earth sciences,guilin university of technology,guilin,guangxi 541006,china;urumqi inspection and testing center,urumqi,xinjiang 830000,china;school of jewelry,guangzhou city university of technology,guangzhou,guangdong 510800,china)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541006 [2]乌鲁木齐市检验检测中心,新疆乌鲁木齐830000 [3]广州城市理工学院珠宝学院,广东广州510800

出　　处：《矿物岩石》2024年第4期1-10,共10页Mineralogy and Petrology

基　　金：国家自然科学基金项目(41962004)。

摘　　要：黑曜岩品种繁多,目前对不同品种在强光照射下呈现不同反光色的原因尚无统一认识。基于此,本次研究选取彩虹眼黑曜岩、金曜岩、银曜岩样品,采用光学显微镜以及电子探针、X射线粉末衍射仪、红外光谱仪、拉曼光谱仪等设备,详细探究3种黑曜岩的矿物学特征以及呈现不同发光现象的成因。在强光照射下,彩虹眼黑曜岩具有蓝绿色、粉红色反光,金曜岩出现金色反光,银曜岩的反光色为银色。3种黑曜岩均具有典型的玻璃质结构,彩虹眼黑曜岩中可见长板状长石微晶、短针状辉石微晶和黑色粒状磁铁矿微晶,金曜岩具有石英微晶和拉长状气泡,银曜岩基质中存在叶片状气泡。3种黑曜岩均由非晶态的火山玻璃(≥95wB%)组成,基质的化学成分主要为SiO_(2),Al_(2)O_(3),Na_(2)O,K_(2)O,SiO_(2)质量分数高达75.08%~79.88%。3种黑曜岩均出现d=0.405 nm处非晶态玻璃的衍射峰以及480 cm^(-1)、714 cm^(-1)、780 cm^(-1)、1 080 cm^(-1)、1 200 cm^(-1)处玻璃质的红外吸收峰。彩虹眼黑曜岩存在赤铁矿、磁铁矿、霓辉石、歪长石等矿物的特征拉曼峰,其反光现象主要归因于不同纳米级歪长石、霓辉石微晶对光的干涉作用。金、银曜岩具有石英、H_(2)O,CO_(2),O_(2)的特征拉曼峰,二者因内部不同大小、形状的气泡及石英充填物对光的漫反射而分别呈现出金色、银色。研究结果能够有效确定黑曜岩及其内微晶、包裹体的种属,为分析不同品种黑曜岩产生特殊光学现象的成因提供科学依据。In this paper,samples of rainbow-eyed obsidian,gold obsidian,and silver obsidian are exam-ined using an optical microscope(OM),electron probe microanalyzer(EPMA),X-ray powder diffractom-eter(XRD),infrared spectrometer(IR),and Raman spectrometer.These analyses aim to investigate the mineralogical characteristics of the three types of obsidian and to explore the causes behind their differing luminescent phenomena in detail,with the goal of explaining why various obsidian varieties exhibit differ-ent reflective colors under strong light.Studies have shown that under strong light,rainbow-eyed obsidian exhibits blue-green and pink reflections;gold obsidian shows golden reflections;and silver obsidian dis-plays silver reflections.The mineral compositions differ as well:rainbow-eyed obsidian contains long tabu-lar feldspar microcrystals,short acicular pyroxene microcrystals,and black granular magnetite microcrys-tals;gold obsidian has quartz microcrystals and elongated bubbles;and silver obsidian features blade-like bubbles within the matrix.The three types of obsidian are composed primarily of amorphous volcanic glass(≥95 w_(B)%),with a matrix chemical composition dominated by SiO_(2),Al_(2)O_(3),Na_(2)O,and K_(2)O.The SiO_(2)content is notably high,ranging from 75.08%to 79.88%.All three obsidian types exhibit diffraction peaks of amorphous glass at d=0.405 nm and infrared absorption peaks at 480,714,780,1080 and 1200 cm^(-1).Rainbow-eyed obsidian shows characteristic Raman peaks associated with hematite,magne-tite,aegirine,and anorthite,and its luminescence is mainly attributed to light interference from nanocrys-talline anorthite and aegirine.Gold and silver obsidians display the characteristic Raman peaks of quartz,H_(2)O,CO_(2)and O_(2).Their respective gold and silver colors result from the diffused reflection of light by bubbles of varying sizes and shapes,as well as the internal filling of quartz.These findings allow for pre-cise identification of obsidian types,along with their microcrystals and inclusions,an

关 键 词：彩虹眼黑曜岩 金(银)曜岩 天然玻璃 拉曼光谱 薄膜干涉 

分 类 号：P575[天文地球—矿物学]