Copper Nos. C12500, C12700, C12800, C12900 and C13000 fire refined tough pitch coppers differ only in silver content. All have electrical conductivity of 98% IACS, volume basis. Minimum copper + silver content of these grades is 99.88%. Silver confers anneal resistance to the materials. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength. It also includes information on forming, heat treating, machining, and joining. Filing Code: Cu-554. Producer or source: Copper and copper alloy mills. Originally published as Copper Alloy No. C17400, September 1990, revised November 1990.