A speculum was discovered in the Zhouyuan area and proved for the first time in archaeology to be a yangsui, an ancient instrument for getting fire in the sun. The present paper reports an analysis of its chemical composition and microstructure. The test results supplement the related record in the “Kaogong Ji” of Zhou Li (《周礼·考工记》) with important evidence. According to its chemical constituents and microstructure revealed, the material belongs to typical high-tin brone with a small amount of lead, and the inner and outer parts of the object are quite different in chemical composition.
