Noctilucous Jade can be founded in caves,
You can get about 7 Noctilucous Jades here. See the photo below to find the way to the cave.
You can get about 20 Noctilucous Jade by visiting these spots.
Mondstadt Region Puzzles, Secrets, and Hidden Chests
Puzzles, Secrets, and Hidden Chests in Dragonspine
How to Beat Monsters/Farm Enemy Drops
Crystal Core Farm Locations
Xiao & Invitation to Mundane Life Event Wish
Ganyu Event & Adrift in the Harbor Wish
Top Mining Spots in Dragonspine