Guide:
Southeastern Eastmarch, south-southwest of Jorunn’s Stand Wayshrine, or southeast of Logging Camp Wayshrine.
Inside the Stormcrag Crypt public dungeon. Start at Jorunn’s Stand Wayshrine and follow the road going southwest until you reach a crossroad. Look south from that position and you can see a wooden door in a cliff, which leads into the dungeon.
As you enter the dungeon, keep following the path to your left. Doing so, you’ll end up inside the large room with the shard. It is located next to one of the two large central stone pillars.