湖北大冶鲤泥湖铜铁矿中单斜铜硝石的晶体结构研究  

THE CRYSTAL STRUCTURE OF ROUAITE FROM THE LINIHU CU-FE DEPOSIT IN DAYE,HUBEI PROVINCE

作　　者：陈佳婧 李昭辉 吴静仪 黄淑婷 廖湘军 刘光华 谷湘平 CHEN Jiajing;LI Zhaohui;WU Jingyi;HUANG Shuting;LIAO Xiangjun;LIU Guanghua;GU Xiangping(Gemmological Institute,Geological University of China(Wuhan),Wuhan,Hubei 430074,China;School of Gemmology and Mineral Resources,Jiangxi Institute of Applied Science and Technology,Nanchang,Jiangxi330100,China;School of Geosciences and Infophysics,Central South University,Changsha,Hunan 410083,China)

机构地区：[1]中国地质大学(武汉)宝石学院,湖北武昌430074 [2]江西应用科技学院宝石矿物资源学院,江西南昌330100 [3]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《矿物岩石》2025年第1期16-23,共8页Mineralogy and Petrology

基　　金：国家自然科学基金面上项目(批准号:41172042,42072054)。

摘　　要：单斜铜硝石(rouaite)是一种罕见的铜硝酸盐矿物,与铜硝石(gerhardtite)同为Cu_(2)(NO_(3))(OH)_(3)的同质多象变体,二者在中国尚无报道。本文首次发现并研究湖北大冶鲤泥湖铜铁矿产出的单斜铜硝石,呈面积0.2~2.0 mm^(2)的皮壳包裹萤石表面,共生矿物有孔雀石、重晶石、赤铁矿、方解石、伊利石等。皮壳厚度约1 mm,皮壳内单斜铜硝石呈微晶-纳米片晶集合体,单晶粒度小于20μm。电子探针分析得到其经验化学式为Cu2.00(N1.02O3)(OH)_(3)。X射线单晶衍射晶体结构分析确定其晶体结构为单斜晶系(全部2763个独立衍射点的精修因子R1=0.0524),空间群P2_(1),晶胞参数,a=0.56030(3)nm,b=0.60728(4)nm,c=0.69360(4)nm,β=94.755(5)°,V=0.23519(2)nm^(3),Z=2。其晶体结构由CuO_(2)(OH)4八面体和CuO(OH)5八面体共边链接形成平行b轴的八面体链,八面体链再共边链接形成平行(001)的八面体层。八面体层与上下侧的孤立NO3三角形共顶链接。层间由氢键相连。Cu—O键长0.1934~0.2467 nm(平均0.2113 nm),N—O键长0.1222~0.1268 nm(平均0.1240 nm),层间距为0.6936 nm(=c)。对倒易空间衍射点的分布分析表明,该结构为b/2晶格的超结构[晶胞参数:a=0.56016(3)nm,b=0.303757(15)nm,c=0.69385(3)nm,β=94.769(4)°,V=0.117652(2)nm^(3),Z=1],按b/2晶胞求解获得P2/m空间群的晶体结构(R1=0.0284),其中与NO_(3)^(-)基团相关的3个O原子位置均出现分裂,占位率仅1/4、1/4、1/2。Rouaite is a rare copper nitrate mineral,a polymorph of Cu_2(NO_(3))(OH)_(3),alongside gerhardtite.Abundant occurrence of rouaite are found at the Linihu copper-iron mine in Daye,Hubei,where it appears as a crust surrounding fluorite of an area of 0.2-2.0 mm~2.Associated minerals include malachite,barite,hematite,calcite,and illite.The crust thickness is about 1 mm,with rouaite forming aggregates of micro-nanometric crystals,with the size of single crystal under 20 micrometers.Electron probe analysis yields an empirical chemical formula of Cu_(2.00)(N_(1.02)O_3)(OH)_(3).X-ray single-crystal diffraction analysis reveals a monoclinic structure(R_(1)=0.0524 for 2763 independent reflections),space group P2_(1),with cell parameters:a=0.56030(3)nm,b=0.60728(4)nm,c=0.69360(4)nm,β=94.755(5)°,V=0.23519(2)nm^(3),Z=2.The structure is characterized by(001)-parallel octahedral layers formed from edge-sharing chains of edge-sharing CuO_(2)(OH)_(4) octahedra and CuO(OH)_(5 )octahedra along the b-axis,with NO_(3) triangles linked to the layers through sharing O corners,and the interlayer connections are made via hydrogen bonds.The Cu-O bond lengths range from 0.1934 to 0.2467 nm(average 0.2113 nm),N-O bond lengths from 0.1222 to 0.1268 nm(average 0.1240 nm),with an interlayer distance of 0.6936 nm(equal to c).The distribution of diffraction points in the reciprocal space shows that the P2_(1) structure represents a superstructure of the b/2 lattice(a=0.56016(3)nm,b=0.303757(15)nm,c=0.69385(3)nm,β=94.769(4)°,V=0.117652(2)nm~3,Z=1),which has a P2/m structure,in which the three O sites boned to N are split with partial occupancies of 1/4,1/4 and 1/2.

关 键 词：单斜铜硝石 硝酸盐矿物 X射线单晶衍射 晶体结构 湖北大冶 

分 类 号：P578.5[天文地球—矿物学]