Jidzin
From PlentyWiki
Jidzin is a phosphorescent material, possibly stone, that lights up in response to touch. It is found in the buried Elderling city under the tree city of Trehaug.
A substance used by the Elderlings. It was used in the corridors of Frengong and the Bingtown delegation brings bells covered in jizdin as a present to Queen Kettricken.