It is also called Yaomingzhu (Night Pearl), Yakoseki (Night Light Stone), Yakosuisyo (Night Light Crystal), and Yaeishi (Night Flame Stone). Yaomingzhu is composed of an aggregate of natural minerals such as tungsten ore, ferberite, cassiterite, quartz, and calcite. It is a type of opal, containing a phosphorescent component derived from rare earth elements, and emits a green light in the dark. Generally, it is amorphous and grayish-white translucent, but some retain a slight phosphorescent component and are crystalline, or have beautiful iridescence that appears in the dark. The former is called Yakosuisyo (Night Light Crystal), and the latter is called Yaeishi (Night Flame Stone). The light is too weak for illumination, but it has been used since ancient times, such as mixing the powder with glue for paint, or as an amulet for children to wear around their necks at night festivals. In Taiwan, there is a mysterious sphere called "Yaomingzhu" that was brought from mainland China. According to one theory, it belonged to Qin Shi Huang, or there is a legend that Genghis Khan possessed it. It emits a green light when placed in a dark place, and it is said to have spiritual properties. The legend of Yaomingzhu dates back to Qin Shi Huang, and it is said that Genghis Khan also possessed a Yaomingzhu called "Kuryu Meishu" (Nine Dragon Bright Pearl). ● By shining light on Yaomingzhu for a few seconds (natural light sources or artificial light sources such as incandescent lamps and fluorescent lamps are also OK), and taking it to a dark place, a soft green light can be emitted continuously. ● This mysterious scene can be enjoyed for several hours. Yaomingzhu is a spherical gemstone that can be seen in the dark with the human eye, emitting light on its own without the aid of external forces.