Now onto my final - I think - Lovecraft story read, and it's one that he wrote himself, not a collaboration, dating from 1919.
The narrator, an English-educated man who spent time in India, is working in a gold mine in the Cactus Mountains, and runs into a curious Mexican man, and then stranger events happen.
It's quite a light story, without too much plot, and fairly short. There's an extended descent underground that fills quite a big chunk. Much of the unknowable and unfathomable. And of course a mystery ending. But, yes, quite nice.