This can be a good alternative to traveling to the nether.
Occasionally an Age will generate with glowstone deposits formed in the same shape as the Crystals.
Glowstone dust is a rich source of EMC. For efficient harvesting, you can use a Mining Laser on the "Explosive" setting. However, this will take up a lot of energy in the laser, so be careful. Find a good sized depression and stand two cannons next to each other, hopping back and forth after firing to maximize blasting power. A Void Ring helps tremendously.