I've found a Skyshard while doing Golden Lotus dailies in the Vale of Eternal Blossom:
What is a Sky Crystal and what is it for?
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Sign up to join this communityBuilding and using a Sky Crystal allows you to fight Alani the Stormborn, who is a rare spawn cruising around in the sky above the Vale of Eternal Blossom. Like the Time-Lost Proto Drake or Aeonaxx, Alani drops a mount when killed: in this case, the Thundering Ruby Cloud Serpent. She seems to respawn pretty fast, so the only hard part here is collecting enough Skyshards.
Source: Wowhead