Guide:
Found inside Yldzuun solo dungeon in the very southeast corner of the map. Entrance to the dungeon is east of Shrikes Aerie wayshrine.
The shard inside Yldzuun is found in the large northeastern dungeon. It is a bit strange that the tunnels have more enemies than the larger areas, like these rooms. Nonetheless, the collectible is at the center of the room, next to the large central pillar. A quest item – Tharayya Journal Entry: 19 – can be found nearby.