Copernicium

Copernicium (symbol Cn) is a solid, extremely reactive transition metal with atomic number 112 that decays into Roentgenium within 12 minutes (in reality, it alpha decays into Darmstadtium as Ds-281within 30 seconds)

Creation
Copernicium can be obtained directly by decomposing a Nether Star, yielding 16 atoms of it, or it can be obtained by fusing two other elements in the Fusion Chamber whose atomic numbers add up to 112 (for example lead, 82, and zinc, 30).

Use
16 atoms of copernicium can be combined with 192 hydrogen, 256 helium, and 64 carbon atoms to produce a Nether Star via chemical synthesis.