Hello all! Before I ask the question, I will clarify that I searched in the forums, read on Sevenless' guide - Metal section, and in the wiki, for this answer and was unsuccessful.
Is the metal occurrence only dictated by one type per underground level? My guess is that it is not, but I have been only getting one type of metal thus far (tin) on both first level (cave) and second (mine shaft inside cave). Also, the personal belief "industry" at maximum gives a "20% chance of getting any metal from mined (common) ore" (quoted from the wiki); I'm assuming any metal refers to soft metals (copper, tin).
Thanks!