Zinc (element)
鋅 centers on the metallic element zinc. It is a specific chemical term with no broader conceptual cluster.
鋅 is a modern character created for the element zinc. It combines 金 (metal) with 辛, which likely contributes the sound シン/シ.
The left side 金 means metal, and the right side 辛 looks like a sharp, hard substance. Picture a hard, silvery metal: zinc.
For シ, imagine a single sheet of zinc metal: sheet -> シ, and the shiny sheet is made of zinc.