Brass

Brass is a material added by several mods.

Esteemed Innovation
Brass in Esteemed Innovation is created using a heated Crucible, inputting three parts Copper, and one part Zinc per every four parts Brass.

Flaxbeard's Steam Power
Brass in Flaxbeard's Steam Power is created using a heated Crucible, inputting three parts Copper, and one part Zinc per every four parts Brass.

Thaumcraft 6
Brass is actually called Alchemical Brass in Thaumcraft 5 and 6, but is still registered as Brass in OreDictionary.

Thaumic Periphery
Thaumic Periphery changes the recipe to use Copper instead of Iron.