The Gemological And Mineralogical Characteristics Of Blue-green Serpentine Jade

Blue-green serpentine,as a rare variety of serpentine jade,has a certain research significance in gemmology.In this dissertation,the mineral composition,micro-morphology and structure were observed by polarizing microscope and scanning electron microscope.The gemological and mineralogical characteristic was studied by basic gemmology test,electron probe microanalyzer?EPMA?,and X-ray powder diffraction?XRD?.The spectral characteristics and color genesis of blue-green serpentine jade were studied by analyzing its Raman spectrum,infrared spectrum,ultraviolet-visible spectrum and so on.Finally,the evaluation factors of quality classification were discussed and the quality was evaluated.The texture of blue-green serpentine is fine,and its luster is mainly glass luster,a small amount of waxy-grease luster.The sample is slight-transparent to transparent,with the refractive index being 1.56-1.57.Its Mohs hardness is 4.95-5.13,and the relative density is 2.55-2.58.The reflection under the spectroscope shows that there is no absorption spectrum.It is inert under the long-wave and short-wave irradiation of ultraviolet fluorescent lamp.The main mineral of blue-green serpentine jade is antigorite and the secondary minerals include calcite,dolomite,talc,apatite and chlorite.There are two kinds of white inclusions,which are rain-shaped and pinpoint shape,and composed of early-formed pyrophyllite,dolomite and calcite.Under the polarizing microscope,it can be seen that the serpentine particles are very small,mainly including scale-like metamorphic texture,leaf-like metamorphic texture,petal-like texture and fine reticular vein-like texture.The characteristic peaks of infrared spectra of blue-green serpentine are 445,561,620,996,1076 and 3675 cm^-1,respectively.The characteristic peaks at 1432 cm^-1 of carbonate are also found in some samples.Raman spectra are mainly composed of a series of characteristic peaks of antigorite at 230,335,375,456,535,640,683,1045and 3695 cm^-1.The characteristic peaks of talc at 195 cm^-1,calcite at 1110 cm^-1,dolomite 1085 and 719 cm^-1,and[PO₄]^3-in apatite were also detected.The main chromatin element of blue-green serpentine jade is Fe,and Mn²⁺has a slight effect on its green tone.The UV-visible spectrum reveals that the coloration principle of blue-green serpentine jade is the result of the comprehensive effect of the d-d electron transition of Fe³⁺ion and the charge transfer of Fe²⁺?Fe³⁺,which is mainly due to the charge transfer of Fe²⁺?Fe³⁺.In this paper,the quality of blue-green serpentine jade was evaluated from six aspects:color,clarity,transparency,texture,crack and fragmentation.