Firestone Hot Springs and that's the skin again

there is some kind of sweet irony about this:

how close she is to the fallen body of her mother-father, and closer still to her brother. since her disappearance they've scarcely crossed her mind; how much (or how little) would it matter to her if she knew?

frankly, her mind was burdened with other things, and those too were cast aside when a wall of sulfur created a barrier between herself and her thoughts. she followed the smell to the water's edge,

[ do you remember when your sister got her first spot? when you got yours? when your throat erupted in a cascade of white you couldn't stop? ]

then recoiled from her own reflection.  half-crumpled, she noticed him, finally — a large, brown shape, just like herself — and startled again.  she should've recognized him ... but she'd spent such little time at elysium to remember who he was.  come on, solomon.  you can't be so scared.

What is this place?