At 71 Mining is it faster to Power mine Iron or Granite?...

granite is always faster i think and it sells for more too

Ohrite, ok then...

 

 

 

Well does anyone know any exp rates for the two options?...

Granite with dropping, using humidy to refill waterskins, wearing varrock armour as top: 50k xp an hour or more

 

(I powermined there when getting mining to 70)

I think iron is generally 35k - 40k an hour, and granite is 50k an hour if you're concentrating. However if you were doing granite, I would personally bank all the 500g ones, as they sell for quite a bit on the GE.