Mysterious Wizard :
This stone contains the power of Gran Kain, the God of Destruction. I'm not sure about it's composition, but I do know that the Stone of Commune was made from a material that Gran Kain cherished dearly.
At the present... One of the Rulers of Hell is said to use this very same material. That would be Halisha. Maybe you could get it by defeating his Minions or Archon?
Luckily, I have heard that Halisha is now sending many of his minions to the Four Sepulchers. It might be a good idea to go make every effort to get there quickly to see what you can obtain.
Hmm.. the Evil Creatures in the Shrine of the Loyal are also Minions of Halisha. If you defeat them, much more powerful Minions will appear. Perhaps they also have the material you seek.
After you find it, go to the Tablet in the southwest of the Wall of Argos.