1_ Purity on Downsing rods will lead to higher purity mines by ignoring the 1.0 purity mines?
2_ Why are pilgrims looking for high Lead, mercury, etc dowsing rods?. With a mine I can only craft metal items.. none of them works for gluttony.. so I don't see the point in this

Edit: As for question 2: It came to my mind that, MAYBE, pilgrims want high lead dowsing rods so that they can get high lead dross to influence they seeds. If that's the reason.. I have to say there are some hardcore farmers out there :S