A hard black stone, such as jasper or basalt, formerly used to test the quality of gold or silver by comparing the streak left on the stone by one of these metals with that of a standard alloy.

• 试金石一种如碧玉或玄武岩的坚硬黑色石头，先前用来检验金或银的质量，用这些金属在石头上留下的划痕与标准纯度进行比较