Nether ores are just like vanilla ores, only you have to smelt them down twice. They include Lapis Lazuli, Coal, and diamonds. However, Nether ores are worth double if you macerate then smelt them rather then double smelt; ie 4 dusts from 1 Nether iron ore, and 2 diamonds from 1 Nether diamond ore! Also, all Nether Ores have a fairly high chance of exploding, sending you into a firey pit if you mine too much of it. Mining these ores can also make zombie pigmen aggresive so watch out!
Industrial Craft oresEdit
These ores, once smelted, are vital to any good industrial operation. Do note that these ores have Redpower equivalents, and one must make sure to distinguish between the two.
Both gems and metals are included in the Redpower ores, and are useful for all of your redstoning needs. Note that Copper and Tin ores DO differ from their Industrial Craft counterparts in both use and data value.
There is only one non-crystal ore in the current version of Thaumcraft 3 which useful in several common applications.