Alumite is an alloy made in the smeltery, using 1 obsidian blocks, 2 iron ore, and 5 aluminum ore. It is the strongest non-Nether metal to be found in the Tinkers' Construct mod and the only material besides Steel that can mine the stronger Cobalt and Ardite ores in the Nether.
Solid and molten Alumite in Casting Basins.