This item can be found by mining Small Obsidian Chunks and Large Obsidian Chunks which will sometimes appear after defeating certain mobs inside Ahn'Qiraj. A Mining skill of 305 is required to mine the chunks. Pre-BC the miners had to max their skill (to 300) and have the +5 Mining Enchant, like Skinners had to have Finkle's Skinner in order to skin The Beast.