Tracking down Ferrium Ore is a little tricky in Arknights: Endfield since it's one of the rarer minerals in Valley IV. In fact, as far as I know, you can only find it in the Originium Science Park area, and accessing this requires a fair bit of progress into the main story.
Even when you arrive, you'll have to progress even more if you want to set up a power grid for mining drills and access the subsequent nodes deeper into the region. All that said, here's where to find Ferrium Ore in Arknights: Endfield, and what you'll need to do in order to mine it.
