Dwarven pickaxe can be found in Kazordoon mines.
We can also obtain this item from the NPC Uzgod. It is needed to complete the Explorer Society Quest's initial mission. This item was implemented into the game in update 7.6 in 2005. That is, a very long time ago. But not so long ago, the item gained a new attribute. It turns out that the dwarven pickaxe can be used with another object (option use with...).
It is likely that Cipsoft made this change in one of its recent updates or bug fixes. Given that the original Dwarven Pickaxe did not have such characteristics this begs the question:
Does Dwarven pickaxe have any additional use? IF so, on what object can this item be used?
Additional question - Why did Cipsoft decide after so many years to make such a change?
Sources:
Tibia - Free Multiplayer Online Role Playing Game - Forum
(713) NOVIDADE! A Cipsoft ALTEROU esse item na calada... Algo grande pode estar por trás. - YouTube