You can harvest Crystals at the following locations....

1. Wind Crystals.
A. Level 30 Miner secondary nodes in East Shroud(Nine Ivies)
B. Level 50 Miner secondary nodes in East Shroud(The Bramble Patch)

2. Earth Crystals.
A. Level 30 Miner secondary nodes in Lower La Noscea(Cedarwood)
B. Level 50 Miner secondary nodes in Lower La Noscea(The Gods' Grip)

Hope this helps.