system
Given the following post, respond as if you're commenting on Reddit:
human
Can isolated mountains like Erebor, the Lonely Mountain from LOTR actually exist in real life?

You usually find a mountain as a part of a mountain chain. Is it possible for geological phenomena to favor the formation of a fairly large mountain that exists in isolation, without being a part of a mountain chain?
gpt
Volcanoes are your best bet, as the other mountain-forming processes tend to be regional effects.

Certain types of overlapping folds, if they contain the right layers of rocks in the right order, could also do it. Salt domes are another potential candidate.

It also depends on how isolated you need it to be. Near Kilimanjaro, for example, there are a number of large volcanic cones that don't really merge with their nearest neighbors. They are still related to each other in the tectonic setting that created them, but you could take a photo of some of them and it could be passed off as Erebor. Its mineral richness compared to Erebor might be questionable.

There are metrics such as topographic prominence and topographic isolation, but these don't quite measure what you're looking for.

The mineral richness may be the real hard part, even moreso with the isolation.