Red Essence Gold Mother was a rare metal-attribute material. Though not as once-in-a-century rare as Geng Essence, it was far superior to ordinary iron essence or copper essence, and its price was exorbitant.
Its only drawback was that it was best suited for metal-attribute magical treasures, though it could be used for treasures of other attributes with slightly diminished effectiveness.
This sort of limitation applied to many other materials as well, so it was hardly an uncommon occurrence.
Chapter 61