Aluminium

Aluminium is a metal added by GregTech and Engineer's Toolbox. The main source of Aluminium is Bauxite Ore. Aluminium Dust can't be smelted in a regular furnace, but requires a Blast Furnace or an Industrial Blast Furnace to be smelted into ingots. Ingots and plates are mostly used as replacements for Refined Iron ingots and plates, but are required in some other recipes as well.

GregTech
The main source of Aluminium is Bauxite, but it can be aquired from electrolyzing various other dusts as well.