This does not have a direct Tolkien reference but it strikes me that this typifies what must have been his sense of work and beauty.
There is a very large salt mine in the Polish town of Wieliczka that was founded in the 13th century and still operated as a working salt mine until 2007. It now produces salt from brine but is mainly a tourist site, in fact a UNESCO World Heritage Site.
Salt once was a crucially important commodity, as witnessed by the salt houses in cities of the old Hanseatic League. Yet the miners not only produced the commercial product, they also devoted their labour to producing beauty. They carved incredible images of historic, mythic, and religious figures and included chapels with altars for religious devotion.
Here's a link to the site for more info:
Wieliczka Salt Mine
I have some pictures of a green dragon and other carvings which I think resonate with Tolkien's vision of art, but I have to figure out how to post them here.
A dragon carved from green salt. No date for this, so I don't know if it is modern or earlier.
Dwarves, based I think on Disney's Snow White and the Seven Dwarves.
One last one showing some of the older carvings in the cathedral, with the altar. And, yes, the chandeliers are made of salt.
