https://ffxiv.consolegameswiki.com/wiki/Ephemeral_Nodes

You'll want to hit these, they are timed, but there is always one up, and they last 4 hours and you can respawn them for the whole 4 hours. Anyway, on my server the yellow sand is 4-10k, red sand is 10k NQ and 20k HQ, the green/brown/blue sand, the 8/8 stuff, is worthless. The light kissed sand is 10k a piece.

The yellow sand you can even farm without spending GP. You also get the crystals and clusters you are farming anyway. I really hope you were not going around just gathering crystals on there own.