The True Dragon gravitational organ within Ian's body requires some Zero Element as an intermediary layer. Theoretically, a True Dragon can create Zero Element out of nothing using its Dragon Soul and the Ether Furnace Core through a special reaction to satisfy the needs of its gravitational organ, but that process usually takes decades, and Ian doesn't have that much time to wait.
Taking something that's already available is the most efficient.
[Edible... honestly, who is the Rites of the Star Gods' edible tag meant for?]
The Glazed-Glass Dragon extends its tail to touch the Zero Element, channeling aether to separate some of the excess renewable Zero Element ore without damaging the core of the Floating Mountain.
