[tshiggins]

Originally Posted by thrash

Statistically, at least, you are going to have a hard time finding anything very different from regular, remnants-of-planet-formation asteroids. The Earth's whole crust is roughly 0.5% of its total mass. The portion where interesting geological processes have occurred is even smaller.

Pallasite meteorites demonstrate that the results of unlikely events can be found, but it's hard to base an entire industry around them. Larry Niven's stasis boxes (e.g.) were a useful narrative device precisely because they were detectable without a lifetime of searching for each one.

Niven also had monopole magnets, made from ferrous metals that aggregated in the absence of a planetary magnetic field.

I'm not sure how they got magnetized, under the circumstances, but in the Known Space setting, they made fusion reactions so much more efficient that finding one repaid, literally, years of prospecting in the belt.

If a belter found several, he or she had a successful career. If the prospector found a fair number more (but less than a couple dozen, IIRC), he or she could enjoy a long retirement in comfort -- or a short one, and leave a substantial inheritance.