Copper deposits are sometimes seen in tissues from pathological conditions. They may be demonstrated with rubeanic acid, albeit with variable success.
The commonest current use for copper is small copper shot, placed into protargol solutions in Bodian type impregnations as an activator. Although considered to be a useful technique for demonstrating nerve fibres, this method is not the most popular.
Copper salts have been recommended for inclusion in preservatives, as fixing agents and as mordants for hematein, but they are rarely used in current practice.