Originally posted by ling.speed:

Its possible but personally i never encountered such situation, its always some special passage. (playing unmodded, mods could make this more of a problem). There is quite a bit of variation in any caves. You may go through 20+ caves of the same type and see a new type of passage still on the next one.

I'm also playing unmodded and there's variation for sure, but I know what look for, unless some Black marble walls can be destroyed with the Black metal pickaxe or if there's very well hidden switches that open those walls (I've looked for these too briefly, but I'm pretty sure they don't exist). Guess this particular mine/cave just glitched out a bit.