Speak with Foreman Oslow in Lakeshire and ask him for Rethban Iron Ore.
I've been meaning to finish my copy of The Stresses of Iron, but...
Well you see, I make my own ink for books I copy. It's my own recipe; it doesn't run or smear, and it dries very quickly. Unfortunately, it dries too quickly! My last batch dried up before I could finish the copying job, and I haven't had the chance to make more ink!
To make more I need Rethban Iron Ore from the Redridge Mountains. Foreman Oslow in Lakeshire is my usual supplier.