I did a search for "urtanium" in the repositoriy, then clicked on the "rareDrops" result.
Huh, weird... According to the code, it should only drop on Uveto, but I can 100% say that I have had it drop for me on Zheng Shi (I have both piercings have have yet to visit Uveto after the patch dropped)
EDIT: Okay, so I just re-checked my piercings, and it turns out I was wrong. I do have two piercings, but I have two Geddanium piercings. Apparantly, it is possible to have multiple of those; I thought those were a one-time drop only, and (repeatedly) misread the name.
Thus, the Urtanium piercing can (probably) only drop from Uveto, as the code states. My bad, sorry!