X射线荧光光谱-X射线衍射研究宁夏贺兰石岩石矿物学特征

摘要

The Ningxia Helan Stone is one of the well-known stones that are used for making inkslab in China.The development and application of Helan Stone is becoming more and more widespread,and therefore,it is necessary to carry out a systematic study.At present,there are only preliminary artificial experiments and systematic study of mineralogy is lacking.The conventional gemological test method is combined with spectroscopic analytical methods such as optical thin section identification,X-ray Fluorescence Spectrometry(XRF),X-ray Powder Diffraction (XRD)to study the gemological characteristics,chemical components,rock structure,and the mineral compositions of the Ningxia Helan Stone and is reported in this paper.The results show that the minerals of the Ningxia Helan Stone include major hydromica and sericite,and minor ferric oxide,sandy clastics,chlorite,and trace amounts of hematite,rutile,and tourmaline.The Ningxia Helan Stone has chemical components including SiO2,Al2O3,TFe2O3,K2O,MgO,TiO2,CaO,P2O5,a refractive index of 1.56 -1.57,a density of 2.81 -2.86 g/cm3,and a mohs hardness of 3 -4.The main color-causing factor of the Ningxia Helan Stone is also discussed.Based on the correlation between the morphology and content of Fe element and the color of the Helan stone,it is considered that Fe is the main color-causing element.The most characteristic parameters of Ningxia Helan Stone have been determined in this study,which provides technical support for follow-up accurate nomenclature and identification method for the Helan Stone.%宁夏贺兰石是中国砚用名石之一,开发应用越来越广泛,对其进行系统的基础研究具有重要的现实意义.但目前仅有初步的人工实验,缺乏系统的矿物学研究.本文采用常规宝玉石学测试结合薄片鉴定、X射线荧光光谱、X射线粉晶衍射等矿物谱学分析测试方法,解析贺兰石的宝石学特征、化学成分、岩石结构及矿物组成特征.结果表明:贺兰石主要组成矿物为水云母~绢云母,次为褐铁矿(氧化铁质)、石英(砂质碎屑)、绿泥石和微量的赤铁矿、金红石、电气石等;主要化学成分为SiO2、Al2O3、TFe2O3、K2O、MgO、TiO2、CaO、P2O5;折射率1.56~1.57,密度2.81 ~2.86 g/cm3,摩氏硬度3~4.初步探讨了贺兰石致色成因,基于Fe元素形态及含量与贺兰石颜色具相关关系,认为Fe元素是宁夏贺兰石致色的主要因素.本研究基本确定了贺兰石的大部分特征参数,为后续建立准确的命名及鉴定方法提供了技术支撑.