I might have come off as more negative than I really meant in my first post.
It should be perfectly possible to be a freelance prospector, I just don't think it should be as convenient as what your suggestion would make it. Before reading your idea I had imagined something with bookmarks and a manually written description, but a standardized data item like you're suggesting would probably work better.
I actually like the concept, but I think it should be possible to tamper with the result using a "data manipulation" skill, or whatever kind of skill could be relevant. The buyers on the other hand should be able to detect the tampering by using a "data analysation" or "deciphering" or whatever skill. With a high enough skill (and especially if the scammer used a rather low level of "data manipulation") there should even be a decent chance at detecting it without buying the item, but the chance would increase after the purchase.
Now, I assume the majority of freelance prospectors would refrain from tampering with their scanning results. They have a reputation to build and uphold. Blatant scammers on the other hand would soon enough end up blacklisted by more and more mining companies and possibly get a bounty hunter chasing them.
I guess there wouldn't be a problem as such with untamperable data items as you suggest, but I think the trade would be more interesting and and more "part of a living breathing world" if unaffiliated prospectors had to build up a reputation because they 'might be scammers'.