Since you just want to mine 500t of anything, though, you can skip using a Prospector entirely if you want to, or only use them on 'roids that drop Painite.
I have a squadmate who has PAINite in his hold atm (he says bounty hunting is easier when he's carrying it)
so all I need is to refine the 500t (497 to be exact as I tried mining once and gave up bounty hunting is where I make my money)