贵州罗甸玉“麻点”和“草花”的物质组成及成因研究  

Study on Material Composition and Origin of Luodian Nephrite With"Pocking Mark"and"Grass Flower"in Guizhou Province

作　　者：张可轩 于海燕[1,2] 柏鹤 张予烨 ZHANG Ke-xuan;YU Hai-yan;BAI He;ZH ANG Yu-ye(School of Earth Sciences,Guilin University of Technology,Guilin 541006,China;Guangxi Key Laboratory of Concealed Metal Mineral Exploration,Guilin 541006,China)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541006 [2]广西隐伏金属矿产勘查重点实验室,广西桂林541006

出　　处：《光谱学与光谱分析》2024年第11期3236-3243,共8页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(42262006);广西科技厅基金项目(2020GXNSFAA159167);广西科技厅基金项目(桂科AD20159027);广西科技厅基金项目(2023GXNSFBA026273)资助。

摘　　要：选取带有“麻点”和“草花”花纹的贵州罗甸透闪石玉(罗甸玉)为研究对象,利用扫描电镜、电子探针和激光拉曼光谱仪测试技术,探讨罗甸玉中“麻点”和“草花”的物质组成和成因。测试结果表明:大的团块状“麻点”分布在部分方解石和透闪石的交界处或透闪石晶界处,小的片状“麻点”分布在方解石或透闪石的小的孔洞中。“麻点”的扫描电镜能谱和电子探针成分分析结果表明其由铁氧化物组成,拉曼光谱特征峰显示为赤铁矿。“草花”呈“沙漠玫瑰”的团球状或无定形状存在于两种结构透闪石交界处或柱状、片状透闪石的边缘。“草花”的扫描电镜能谱和电子探针成分分析结果表明其为锰氧化物,拉曼光谱特征峰显示为钙锰矿(640、356和287 cm^(-1))或水钠锰矿(636、582和506cm^(-1))。依据带有“麻点”和“草花”花纹的罗甸玉的成分和结构特征可以推测:罗甸玉中大的团块状“麻点”是后期富含Fe的热液与透闪石玉成矿热液混染成矿,而小的片状“麻点”则由富Fe热液充填形成。“草花”周围呈浸染状的叶片状或柱状透闪石是由富Mn热液与透闪石玉成矿热液混合结晶形成Mn含量比较高的透闪石,后期富Mn热液运移到柱状或片状透闪石的边缘或裂隙处析出形成钙锰矿或水钠锰矿。The composition and origin of“pocking mark”and“grass flower”in Guizhou Luodian tremolite jade(Luodian nephrite)were studied using scanning electron microscopy,electron probe,and laser Raman spectroscopy.The test results show that large clumps of“pocking mark”are found at some of the junctions between calcite and tremolite or the crystal boundary of tremolite,and some small pores of calcite or tremolite are distributed with a small flake“pocking mark”.Scanning electron microscopy(SEM)and electron probe(EPM)analysis showed that the“pocking mark”was composed of iron oxide,and the Raman spectral peak of the“pocking mark”was hematite.The“grass flower”is the globular or amorphous shape of the“desert rose”and exists at the junction of the two structural tremolites or the edge of the columnar and lamellar tremolites.The“grass flower”in Luodian nephrite was identified as manganese oxide by SEM energy spectrum and EPM surface scanning,and the characteristic peaks of Raman spectra showed that it was calcium manganese(640,356 and 287 cm^(-1))or hydrohydroxyl manganese(636,582 and 506 cm^(-1)).According to the composition and structural characteristics of Luodian nephrite with“pocking mark”and“grass flower”patterns,it can be inferred that the large clumps of“pocking mark”in Luodian nephrite are caused by the mixing of Fe-rich hydrothermal and tremolite ore-forming hydrothermal.In contrast,the small flake“pocking mark”is formed by Fe-rich hydrothermal filling.The disseminated lamellate or columnar tremolite around the“grass flower”was formed by the mixed crystallization of Mn-rich hydrothermal solution and tremolite jade ore-forming hydrothermal solution.In the later stage,the Mn-rich hydrothermal fluid migrated to the edges or cracks of the columnar or lamellate tremolite and precipitated to form calcimanganite or birnessite.

关 键 词：罗甸玉 麻点 草花 成分 微形貌 

分 类 号：P575[天文地球—矿物学]