When mining with a Heavy-Duty pickaxe(or Diamond), there is a chance to recover raw meteoric iron. The ingot can be made by smelting the items you get from mining meteors in a furnace. Meteors randomly hit on the surface of the moon and you will likely run into one while exploring the surface of the moon.They can be used to make airlock frames.

They can be crafted into airlock frames (and heavy duty tools?) can some one please organize this for me? thanks

It can also be used to make Heavy Duty Plates from tier 2 to make a tier 2 rocket.