After some practice with procedural textures in cycles I created the copper material, from startr to finish, applying the knowledge acquired thanks to Kent Trammell classes and Eduardo Maldonado blog. In this material, I have put a lot of controls to configure various values ??of roughness, reflection and color correctly. This material can be used for new or old copper just changing some parameters in the material.
I am very happy with this shader because with small adjustments like color may be used for other metals, eg brass
BTW: I miss some kind of separator for inputs in groups to keep everything organized
You can download this last material ;)
(You can use it commercially in your models.You can not sell it as is, with minor modifications or included in repacks etc..)