Is this Britain?

[drakesaint]

Spent a week prospecting. Only found Cassiterite. Is this world the recreation of Britain, where you can only find tin?

[Potjeh]

There's actually a famous historic malachite mine in Great Orme, Wales

But anyway, your problem is you're prospecting in one general area. Move a bit further out, ore comes in large clusters. For example, where I'm at there's nothing but chalcopyrite on north side of the lake, and nothing but cassiterite on the south side.