Gemmological And Mineralogical Characteristics Of Malipo Emerald From Yunnan Province

In this paper,emeralds from Malipo,Yunan,as the subject of studies.The author compared Malipo emeralds with different locality emeralds by studying with features of Gemmological and mineralogical,for the key features of origin tracing.The results show that surrounding rocks of Malipo emerald are felsic pegmatite,which mainly composed of quartz?90%-80%?,albite and potassium feldspar?10%-5%?,and contain some muscovite,biotite,phlogopite,scheelite,pyrite,pyrrhotite,chlorite,stone and other secondary minerals.The X-ray diffraction?XRD?result show that the lattice parameters of Malipo emerald samples: a=0.9217 0.9249 nm,c=0.9200 0.9202 nm.The data of c/a =0.9983 0.9947 indicate that mainly type of somorphism of Malipo emerald is type-‘normal-octahedral'.The Chemical composition analysis reveal that in the [BeO₄]-tetrahedrold,parts of Be²⁺?49268.2ppm 52527.0 ppm?can be replaced by Li⁺?321.8ppm 593.2ppm?.In the [AlO₆]-octahedral,Al³⁺can be replaced by Cr³⁺,V³⁺,Fe³⁺,Fe²⁺,Mg²⁺,Mn²⁺,Sc³⁺,Zn²⁺,Ti⁴⁺,Ca²⁺ etc.The replacement degree of Al³⁺is 5.2% 8.5%.The content of alkali oxides of Malipo emerald is 0.38wt% 0.78 wt %,which is mainly Na⁺ and Cs⁺,low K⁺,Rb⁺.The LA-ICP-MS analysis results show that the content of V³⁺?1063.0 ppm³206.1 ppm?far more than Cr³⁺?58.2 ppm²46.5 ppm?in Malipo emerald samples.The X-ray Energy Dispersive Spectrometer?EDS?analysis results show that the ratio Cr/V of Malipo emerald samples between 0.039 and 0.24,which is belongs to type-II emerald.The UV-visible absorption spectrum?UV-Vis?testing results show that,the cause of color of Malipo emerald samples which effect jointly of Cr?V?Fe.Compared with other origin of emerald,the absorption of V³⁺of Malipo emeralds is more obviously.The origin characteristics of Malipo emeralds are characteristics of chemical composition and UV-Visible absorption spectro.There is a obviously different between Malipo emeralds and other origins emeralds which is the content of V₂O₃ normally more than Cr₂O₃ in Malipo emeralds.Though the UV-Visible absorption spectrum testing,it is known that the absorb peak of red-orange light?617nm?caused by V³⁺,and absorb peak of purple light?386nm?caused by Fe³⁺.Both of absorb peaks are offset to the long wave.