There are five materials in Dungeonmans, corresponding to the five tiers of equipment you can find. You can give any equipment you find to the Blacksmith at the Academy to melt it for you into raw materials, based on the item's tier:
Tinsteel (*)
Burlylium (**)
Crushonium (***)
Foominite (****)
Starmetal (*****)
These materials are also used for the five tiers of stat rings.