Is there 'darkness' at the bottom of every mine if you go deep enough?

Question

In the January 2004 issue of The Magazine of Fantasy and Science Fiction, they ran a story called "Nimitseahpah". In this story, there is a 'darkness' at the bottom of a mine:

Then that thing that all miners dread came to pass. Something big went wrong, and almost all of the 150 men in the tunnels that day were killed. The details of the disaster were sketchy, Jesse said. Whatever happened was so unusual that the whole incident lay cocooned in legend and rumor. The survivors (there were very few) spoke of things no sane person believed. The mine had come to life. Or the miners had pierced the darkness, and it had devoured them in retribution. All the machinery stopped at once - the air compressors, the big water pump, the man skips - and could not be restarted. Men were sucked bodily into the void, seven thousand feet down. Rescue parties disappeared. Not a single body was ever recovered.
_{Page 10}

Something as cold as a January night seemed to be dragging me through the sand toward the main shaft of the Pahpocket. I stretched out my arms, grabbing... ...It felt exactly as if the ground around the shaft had tilted and risen upward like the sides of a funnel.
_{Page 22}

There's obviously something down there; that's the whole point of the story. However, is this at the bottom of every mine if you dig deep enough or only at the Pahpocket?

Answer 1

It was, as well, the deepest in history as far as anyone knew, and there should have been many who knew, for the entire state was aswarm with mining experts in those days.

First tier of the first part, I don't have access to a paper version of the novel

If it's in every mine at a given depth, nobody witnessed it elsewhere empirically.

However, Nev's experience tells us otherwise (as the word Darkness is so central in the short story, I don't believe it could be accidental):

The place where the light meets the darkness. The balance. It feels like . . . like the afternoon before a storm. A hum. Inside you

Nev speaking, Part 6

It's unclear whether it's the perception of darkness that Nev interiorates, or darkness itself, but I don't think that Nev was contaminated in some way: his perception of Darkness, in my view, comes from his Paiute education. Darkness exists everywhere, but was bursted at its heart:

The fact that Nev had been raised by a Paiute explained a lot about his behavior, and also about the way the other children treated him. [...] They said his Indian mother had taught him black magic.

Part 4

had pierced the heart of darkness

OP's quote

TL;DR: it's not darkness the miners pierced, it's the heart of darkness. I don't believe anything separates the mine from others, except it went deeper than most, exposing darkness too much.