Abstract:Balin Stone consists predominantly of kaolinite group of minerals comprising kaolinite and dickite. The major chemical compositions are Al2O3 and SiO2, with minor oxide of iron, manganese, titanium etc. Balin Stone has many varieties according to the different colors, and the samples collected in this study are yellow in color. Transparence is an important factor affecting the evaluation of jade. In this study, several tests were done to investigate the factors related to the transparency. Transmittances were obtained from the ultra-violet and visible spectrophotometer, and then the transparencies of the samples were divided into three levels: good, medium and poor. The scanning electron microscope provides information on the texture of the stone. The kaolinite crystals mostly form a scaly or micro-granular texture. The authors also obtained the particle sizes in samples with different transparencies. The results of the particle size analysis indicate that the smaller the average sizes are and the more homogeneous the size is, the better the transparency is. X-ray diffraction were performed for the sample power, and the X-ray pattern was consistent with the pattern of kaolinite group of minerals standard. The crystallinity was also calculated to check its relation with the transparency, and the authors have reached the conclusion that the sample with the maximal crystallinity has the finest transparency while the one with the smallest crystallinity has the poorest transparency. It is thus held that there are several factors that can affect the transparency of the Balin Stone, i.e., ① the average granular size: stone with small size will have better transparency; ② the homogeneity of the grain: the more homogeneous the stone is, the more transparent the stone is; ③ the crystallinity: the crystallinity is a parameter that represents the degree of order, and it is inferred that the more transparent one has better degree of order or has a higher crystallinity; ④ the inclusions and cracks in the stone: it is obviously that their existence will degrade the stone's transparency. The transparency is a prior factor for the value of the jade. This study can provide information for researchers, who can apply the methods to other kinds of jade. The result obtained by the authors can also be useful to the customers. While choosing the Balin Stone, they may at least take the inclusions and cracks into consideration.