Stone slab

A Stone Slab is mined in the TzHaar City mines, and gives 40 mining experience when mined. If you use a chisel on this with a hammer in your inventory, you get 20 crafting experience and a pillar. It is used in the TokTz-Ket-Dill quest.

It is also the heaviest item you can have in the game (Is this true?). It has the same weight as a Barrel of coal-tar, and if you hold a full inventory of this, you can weigh up to 896kg.