http://en.wikipedia.org/wiki/Opioid#Global_shortage_of_poppy...
Opium poppies grow well in Afghanistan and farmers already know how to cultivate and prepare it for shipping in large quantities.
Potential mineral riches are spiffy and all, but it seems foolish to toss money at projects which require large-scale construction and worker training when an existing high-demand product already exists to productively employ the populace.
These folks don't yet have infrastructure capable of large-scale mineral extraction. Why not build upon useful agricultural exports and start from there?