Throughout the asteroid field are scttered small, spider-like robotic mining units attached to various sized asteroids. They have been inactive for centuries, but they still hold small amounts of whatever they last mined. This can be fuel, gems, ore, or metal.
Hard to detach from the rocks themselves, and harder still to pry open, most just leave them be, as often, the payout is not worth the time put into it.
Intergalactic Blues
We are a literate sci-fi roleplaying guild