Asteroid Prospecting and Mining - rule book, supplement, whatever?

[downer]

I would think that such questions should be solved by the intentions of the GM. If you want to keep the characters barely flying, Firefly style, make most asteroids poor or let the minerals traders be stingy and/or fraudulent. If you want them to make a killing, have them hit a mother lode. Simply assign the market value of any given asteroid according to the needs of your campaign and explain any value shifts in terms of variable supply and demand. This could result in some fun plots, like:

- PCs find rich rock, but must protect their treasure from pirates and thieves
- PCs find rich rock, but someone else presents an older claim and they must defeat them in court
- PCs chasing rumors of "the big one", but find only dirt
etc. pp.

Coming up with tables and rules seems somewhat unnecessary, unless you want to make the process itself, rather than the characters' hopes and fortunes the focus of your campaign.