The Rock Rats by Ben Bova (Review).

Lars Fuchs is the geologist turned pirate, murderer in this sequel to Precipice by Ben Bova. The Rock Rats are a group of miners prospecting for ores and minerals, trying to make a living or a big financial break usually hindered by interplanetary corporations such as Humphries Space Systems, run by Martin Humphries, the villain that persists to make it harder for the underdog to take him down. Outwardly lusting after Fuchs wife, and at the same time seeking to eliminate Fuchs, as he has turned into a liability expendable. Competing fiercely with the Astro Corporation, Humphries is finding it extremely difficult to keep his thugs alive, yet he can lose billions and still have the power to feed the judicial system to see thing his way. Eventually Fuchs is tried for piracy and murder, his wife which he abandoned agrees to marry Martin Humphries, as long as he spares Lars Fuchs life, as he gets exiled for another possible continuation to the story.