Thamium ingots can be used to make Thaumium Armor, tools and weapons. Armor has a better durability than iron, and has the same enchantibility as gold, while weapons and tools have the same durability as iron and enchantibility as gold. Thaumium has a higher precantatio than is required to craft it, so 4 thaumium and 1 Iron Ingot will create 5 thaumium, but the Crucible can only hold 40 items.
Here's a video that shows you how Thaumium works http://www.youtube.com/watch?v=7IjgBp7E3XU
Required Research: Basic Transmutation
|Aspects Required (Warning Spoilers)|
A metal such as this has many applications in the crafting of more advanced thaumaturgical devices.
After that they will have to put 8 Metallium aspect and 4 Precantatio aspect in addition to 10 Vis from a wand used on the Crucible yielding 1 ingot of Thaumium