Preliminary Study on Dark-green Albite Jade

The gemmological characteristics,mineral components,texture feature and degree of order of the dark-green albite jade are systematically studied by using many kinds of analytical methods,such as conventional gemmological methods,polarizing microscope,electron microprobe and X-ray powder diffraction.The results show that the refractive index of the dark-green albite jade is about 1.53with density of 2.64g/cm³.In the petrographic thin sections,the mineral crystals are mainly hypidiomorphic to xenomorphic granular,short prismatic and fibrous.There are two major kinds of texure,mylonitic texture and fibrous granular crystalloblastic texture.The main mineral components are albite and amphibole.The results of chemical compositions of samples by using electron microprobe are that the values of An of albite is less than 0.006,which suggests that the albite ingredient is very pure.The major amphibole type is magnesioarfvedsonite.Based on the X-ray powder diffraction data,the degree of order of albite structure has been calculated,which is very close to 1.It is completely ordered low albite.The formation temperature is lower than 300℃.The present paper makes up some deficiencies in the research on albite jade and provides some meaningful theoretical achievements for the further systematic and comprehensive research on it.