So given the rarity of the ores in question, I don't have a huge sample size here, but something seems like it might be a little off.
I unlocked Fluorescent Fountain tonight, and my assumption was that Lorium would be a little more common than it was in Growling Grotto, where it's an extremely rare drop. What I've found, instead, is that the drop rate is about on par with Chaosium, actually I've had an easier time getting Chaosium, which seems odd considering it's the tier above Lorium. There's also a massive amount of Silver down here, but honestly it's not copper so I'm not gonna complain too much lol. In any case, I think it might be worth looking into the Lorium rate, as I think it either may not have been raised for the higher level venue (where it would stand to reason it would be at least slightly more common) or put on the same level as Chaosium (which you assume would be harder to get because it's a higher rarity/tool tier).
It might just be terrible RNG, or maybe it's intentional, but it strikes me as odd so I wanted to mention it.