Tin (Sn 50). In the Shōsō-in, tin appears primarily in copper alloy form such as white bronze and sahari. Tin is a crystalline, soft, malleable, metal that melts at low temperatures. Adding tin to copper helps in the casting by lowering the melting temperature, which makes the molten metal more fluid. This alloy becomes denser and harder than pure copper. Tin is rare in Japan.