Under what conditions can prospecting an industry fail?
Recently I threw away big money -- over a million cash -- attempting to prospect an Iron Mine. Well, I didn't get a new mine; I didn't even get a failure message. Before I attempt that again, I'd like to know if my chances are determined or random. If I prospect again, am I guaranteed to fail? Are there underlying... resource values of some sort... that either are, or are not present? Or is it, perhaps, merely a matter of topography? In which case, might I do a little landscaping first and make the prospecting succeed? If so, does height matter or only a sufficiently large, flat area?
I'll note that my current NARS Mountainous map has no Quarries nor Clay Pits. This is what leads me to think that there's just insufficient flat land; both are quite large.