Z-Cobalt was a metal only found on Zeno. It is named after the Earth metal, Cobalt, because the two share both similiar properties and appearances.  Z-Cobalt, however, was much more dense and durable than Cobalt, and because of this it was used in the creation of multiple things such as Purged Darksteel and the blades of Synthetic Plasmablades.  It is extremely valuable to the rest of the Milky Way.  Z-Cobalt, like the Earth cobalt needs special handling as it causes contact dermatitus.