These items are the basic crafting materials.
The fundamental items are the material ingots, gained from the various ores. Copper Ingots, Tin Ingots, Mythril Ingots, and Adamantium Ingots are gained from smelting the respective overworld ores. Onyx Gems are dropped directly from breaking Onyx Ore, the Nether ore.
Lastly, this group includes the Copper Bucket.
Bronze Chunks, Thyrium Chunks, and Sinisite Chunks are the result of utilizing alloy recipes in the Fusion Furnace. Small and medium chunks are crafted into large chunks, and then large chunks are smelted into ingots in a regular Furnace. (Alternatively, the chunks can be smelted more quickly in the Mythril Furnace, or they can be smelted in the Onyx Furnace in the hopes of gaining extra output ingots.)
The ores are either smelted into ingots (Fyrite, Malachite, Illumenite, Argonite), or the ores drop gems when harvested (Ashstone, Dragonstone). Ores that are smelted into ingots can be smelted more quickly in the Mythril Furnace, or smelted in the Onyx Furnace in the opes of gaining extra output ingots.
In the WildEdit
Desert Temple chests can contain the Adamantium Ingot.
Chunks, gems, and ingots from the Fusion Furnace or Netherrocks plug-ins do not occur in chests.