First go to Edron and head up to Edron surroundings and you will find this cave to west of cyclops mountain
You gonna enter inside of the cave and use your pick or your squeezing gear of girlpower and right click where i show you on the picture below
Now that you’ve used the pick you will recieve the luminescent crytals and you must wait here to get another one or you can run around the cave using the crystals or just stand in a spot since they respawn rather quickly. You can get either 1, 5 or 10 crystals when you mine them.
Now that you got all luminescent crystals you wanted , you can use (the cube) where i show you on the picture below
As you can see i have the luminescent crystal outside the cave :). Hope you guys enjoyed!