Where do I find mithril?

[Triple G]

As the title says. I just beat the boss with the puppets and still have never seen a node or drop.

[Tornadoawe]

From the Ore Nodes on the map, Mithril drops from the area after Braer Castle.
The only enemies that drop Mithril Ore are two of the dragon enemies in that post-Braer area, and Cave Snatchers (worms) from the area past that.
Maybe some chests drop it earlier than that, but no grindable places before Tome Mistress.