Iji offers you a unlimited Somber Smithing Stone [1] and [2], plus a finite ... Clear them all out, and you'll find a treasure chest with the Smithing Miner's Bell Bearing [2] inside.

To get this Bell Bearing, you must head to the Mountaintops of the Giants and find the first Site of Grace of the place, the Zamor Ruins Site of Grace. Then, head south through the small arcs next ...

To get this Bell Bearing, you must kill the Crystalian Spear ... Progress further to find a giant door; open it to find the boss battle arena.