Nickel

Ferrous ore is added by Thermal Expansion. When GregTech is installed the metal is renamed and replaced with Nickel. It is used for making Invar and Heating Coils.

World Generation
Ore world generation is controlled in the config files of the mods that add it. To have only one type of an ore generated turn off the ore generation in the config files for all but 1 of the mods. Thermal Expansion and CoFH Core offer you the ability to tweak the spawn rate of all modded and vanilla ores.