You are incorrect.

You can get shards and crystals from elementals. I killed several of them and got reliably shards and crystals.
I killed the water ones near gridania and got watershards and i killed the wind ones in the south shroud and got crystals.

Those might not be enough for you but there is a second possibility.


(I'm lvl 26, i couldn't check if lvl 50 ones drop cluster, but it is most likely because FC members placed clusters in our bank, and these member only fight)