This discovery has just recently been made by geologists which had access to the country only for the last couple of years. These resources can and will make a great contribution to the rebuilding of the country providing an improved security situation allows for them to be properly developed and exploited.
To suggests these recently discovered resources were the original grounds for the invasion is absurd..
However, that western (especially US) corporations will move in and cut themselves a share (if the Afghan government isn't watchful, a big chunk) of the profits now that these resources have been discovered is not unlikely.
But let me ask you this more general and most likely outrageous question for some:
Would it be to much to ask that the West may buy some of these resources from the Afghans after having invested billions to rid it of the Taliban, rebuilding its nation and training its army and police? Maybe even at a small discount?
Remember the resources were not the reason for the invasion, otherwise the question would of course be absurd.
If handled correctly, this could be a win-win situation.