It is interesting to note that the decline in gold value from 1500's was a function of supply -> Spains plundering of massive amounts of gold from the "new world". Then in the 1800's there was the increase in supply coming from the gold rushes of US & Australia, followed by the big South African mines into the middle of 1900's.
Going forward it is very unlikely there will be any new big bonanza discoveries to effect supply greatly... the POG story will really be a function of demand.
