Arcanite Bars work into numerous classic "World of Warcraft" crafting recipes and are needed to create the legendary weapons Sulfuras, Hand of Ragnaros and Thunderfury, Blessed Blade of the Windseeker. Crafting them would be a simple matter of smelting Arcante Ore -- if Arcanite Ore actually existed. Instead of being smelted, Arcanite Bars are the result of alchemy, transmuted from Thorium Ore and Arcane Crystals.
Required Professions and Materials
In order to create Arcanite Bars without the help of a friend, you need both the Alchemy and Mining professions, and a minimum skill of 230 for Mining and 275 for Alchemy. Being a transmutation master will help speed the process, as it grants a chant to generate extra bars from each transmutation. "Transmute: Arcanite" requires one Thorium Bar and one Arcane Crystal per Arcanite Bar. Thorium Bars are smelted from Thorium Ore, at a one ore to one bar ratio.
Where to Farm Thorium
Thorium Ore and Arcane Crystals are both mined from Thorium Veins. While every vein will have the ore, the crystals have a limited drop chance -- 13 percent at best, from Rich Thorium Veins. The best places to farm these ores are Winterspring and Un'goro Crater, as each has many nodes and easy-to-follow routes along the mountains surrounding the zones. If you find too much competition in one zone, head to the other to try for more nodes. Don't bother having a Jewelcrafter prospect the ore hoping for more crystals -- no ore contains Arcane Crystals.