Drywhisker Gorge is a gorge cutting through the mountains in the eastern section the Arathi Highlands, northeast of Hammerfall. At the end of the gorge lies a cave. It is currently inhabited by the Drywhisker kobolds. Deep within the cave, a mysterious stone shard can be found in which a piece of the essence of Princess Myzrael was trapped.
By the time of the Battle for Stromgarde, the Drywhisker kobolds still remained active in this area. Among them, Geomancer Flintdagger and Overseer Krix were priority targets. Krix eventually succumbed to his opponents, and the that was to be his dinner was saved and found a new home.
Getting to the cave
The cave entrance can be found at. It appears to be due east of Hammerfall on the map. Kobolds are found to the south and east and that is the route that has to be taken to the cave, as the northwest border of Hammerfall is guarded.
The path to the cave can be found on the east side of Hammerfall. Look for a long, moss-covered log then a boulder in front of a tree. Stand facing the hills with your back to the boulder and look up. Beyond a grassy hillock, you will see a small bush and a tree top between a "V" formed by the taller hills in front of you. Head up the hill past the bush and you will see that the tree has another boulder in front of it; go around these heading straight up. You will pass several more bushes and the path will curve toward the left. At the top of the rise, bear left and very shortly thereafter you will see the cave.
This cave was the only known source of prior to the Cataclysm.