In my opinion there should be no hard cap on any resource. I agree some reources should be there in abundance while others should be really scarce.
However I would prefer this to be regulated through the find rate of the resources, not a hard cap.
Lets say you only find pyrite once every 100 drops...random number. It would still be valuable but noone could completely corner the market.
I find a scenario where one person or a group of people have the possibilty of stockpiling the entire stock of any resource rather disturbing as it could bring the whole game to a screeching halt.
However as long as there is profit in it, stuff like that will happen.
Anyways my