Cuprum is the Refinement of Copper, or the Self. It is the practice of mysticism as a means of taming Torment and to gain solace (rather than enmity) with Nature. Prometheans who follow this practice tend to be the most comfortable with (and capable of) surviving in the wild.
A Promethean seeking the Refinement of Copper focuses on the Self. By itself, this might seem like the Cuprum are self-aggrandizing or even egotistical, but this is not at all in the spirit of the Refinement. To pursue the Refinement of Copper is to discover the inherent mutability of one's flesh, to open up to the myriad sensations in the world and to live in concert with Nature. The Cuprum believe that by doing so, they can mitigate the effects of Torment, learning how to exist in a world that rejects them — or perhaps even teaching the world to keep a space for them. Like the other Refinements, Cuprum is not a goal to be reached but a process to undergo. Unlike the others, it is an inherently lonely one, and progress along the path to this Refinement is hard to gauge.
Most Prometheans find themselves with the Refinement of Copper at some point in their existence as the pressures of Disquiet force them away from humans more and more constantly. The Osirians and Frankensteins, in particular, will remain Cuprum for long periods of time because of their loner natures. The Galateids, who practically thrive on humanity, are least likely to follow this Refinement.