From Granblue Fantasy Wiki
Elemental Quartz are rare materials needed for advanced crafting. Players typically get them from reducing unneeded and summons.
|Uncap Omega weapons to 4★||200|
|Uncap Cerberus to 4★||60|
|Uncap Fenrir to 4★||60|
|Rebuild Class Champion Weapons||50 of the replica's element|
|Uncap Xeno Weapons to 4★||300|
Elemental quartz are primarily obtained from reducing summon stones.