Tin dross is a byproduct formed during the smelting or soldering processes involving tin. It consists of oxidized impurities and molten metal that float to the surface of the tin melt. Tin dross typically contains a mixture of tin oxide, other metal oxides, and residual tin. It is often recycled to recover the valuable tin content through refining processes. Tin dross is commonly encountered in industries like electronics manufacturing and metal plating.