interesting days ahead !, page-8

Not really debatable - The minerals that need this type of infrastructure are iron and coal, most others are processed to a large degree on site, and do not need large scale haulage infrstructure. A huge amount of exploration was done in the seventies looking for DSO, thats when JH and Weld Range were found, these and others are only viable now with present iron ore prices and as magnetite mines.
As for other commodites, wheat, sheep and cattle were traditional. Wheat has its own infrastructure and doesn't extend very far along the line anyway, wool is no longer a pound for a pound and most stations have been destocked and cattle, who knows but you dont see many.