许慎在《说文解字》中曰:“玉,石之美者。”在古代所有美石皆称玉,这包括了我们现在已知的硬玉、软玉、水晶、玛瑙等,只是根据其品色的不同有不同的称谓。到了近代接受了国外科学的矿物测验分析,对玉石有了详细的界定,水晶、玛瑙等则不再属于玉石之列。玛瑙,在矿物学上称为玉髓,化学成分为含不同杂质的二氧化硅,呈不透明至半透明状,似玻璃或蜡状 Xu Shen in “Shuo Wen Jie Zi” said: “jade, the beauty of the stone.” In ancient times all the beautiful stone are called jade, which includes what we now know jade, nephrite, crystal, agate, etc., just based on its Different colors have different titles. In modern times to accept the foreign scientific mineral test analysis, a detailed definition of jade, crystal, agate, etc. are no longer part of jade. Onyx, known in the mineralogy as chalcedony, its chemical composition is silica with different impurities, opaque to translucent, glassy or waxy