Study On The Mineralogical Characteristics Of Laos Stones

“Laos Stones”is a new type of seal stone material produced in Hongshan,Pugang County,Pohang County,Azov Province,Laos.This paper will focus on the gemological characteristics of"Laos stones".The species will be systematically analyzed through conventional gemological test,microscopic observation,infrared spectroscopy,X-ray powder diffraction,laser Raman spectroscopy,XRF test,scanning electron microscope and other test analysis methods,which are related to the composition,structure,and colorigenic causes of“Laos Stones”.This essay will also explore the difference between the“Lao stone”and the domestic seal stone and evaluate its quality.The colors of“Laos Stones”are mainly red,pink,yellow,white,blue-white,taupe,etc.Their transparencies are vary from translucent to micro-transparent,relative density is 2.52².60,refractive index is 1.56,red"Laos Stones"under microscope contains Granular red inclusions,yellow"Laos Stones"is more delicate,no obvious graininess,white"Laussian stone"has no obvious impurity mineral distribution.The main mineral components of Laos Stone are kaolinite,dickite and pearlite,which are measured by infrared spectroscopy.Some Laos Stones samples contain a mixture of two minerals.The"Laos Stones"specimen mainly has three sets of absorption peaks in the absorption zone of the functional group hydroxyl group,which are located near 3701³694cm^-1,around 3656³652cm^-1 and around3629³622cm^-1,which can be distinguished according to the peak type.Stone constitutes a multi-type of minerals.X-ray powder crystal diffraction measured the hematite absorption peak characteristic of the red"Laos Stones",revealing the existence of hematite in the red"Laos Stones".The results of laser Raman spectroscopy also show that the red spot impurity is hematite.Studying the absorption characteristic peak of laser Raman spectroscopy can provide a method for non-destructive differentiation of"Lao stone"components.Ultraviolet-visible spectroscopy results show that the color of the"Laos Stones"is related to Fe.Under the polarizing microscope,the red"Laos Stones"'s color are due to hematite,which had been mixed in the form of aggregates and gathered in the gap of the mineral layer.The color of the yellow"Laos Stones"is presumed to be caused by goethite.X-ray fluorescence spectroscopy showed that the content of iron gradually decreased with the color of"Laos Stones"from dark brown to red to yellow to white.The kaolinite minerals that make up the"Laos stones"are cryptocrystalline aggregates.The aggregates are finer in shape,generally fine-grained,and fine-grained particles are interwoven.Under the crossed polarizer,it is grayish at a level.It is mainly seen that red or dark brown impurities exist in three ways.The kaolinite minerals are mainly slab-like,granular,irregular scaly and other cryptocrystalline structures with diameters ranging from 1 to 20?m.The well-crystallized kaolinite minerals are pseudo-hexagonal flakes,which is similar to the inlaid stone structure similar to other origins.The size of the composition of the mineral directly determines the fineness of the texture of the“Laos stones”,which means the smaller the particle size,the finer the texture.