TGG, not quite right. It is a contract that Qantas has with FMG, and they are essentially wet-leasing the aircraft from JQ with crew and all the bells and whistles. Same as Qantas using Cobham-operated 717s.
A source in the know told me a while back that the A320 is better suited to some mines with narrower runways over the 738s, hence why VARA will hold on to theirs for some time.