Unknown
From AfterWiki
Many resources and craft-able components are shown "Unknown" if you do not have enough stages of certain skills. The required stages to unlock different stones can be found at the Unlock Level page.
The following table should be helpful in finding the resource behind the "?". They are all listed in alphabetical order, with the refined resource appearing before the unrefined resource. Resources with only one entry, certain crystals, do not have an unrefined form.
