
Well, the Shards/Crystals/Clusters, if I remember correctly are formed when there is an excess of Aether left over from someone's Aether not transferring back to Hydaelyn when they die. Just as it can form into ghosts and the like, it can also coalesce into crystals.
Also, Thanalan produces 3 elements of crystals when mining.
Also, Thanalan produces 3 elements of crystals when mining.
Aduu Avagnar, The Wanderer: Wiki