Magnesium (element)
鎂 refers specifically to the chemical element magnesium. It is a modern character created for scientific use and has no broader conceptual range beyond this single meaning.
鎂 is a modern character coined for the element magnesium. It combines the metal radical 金 with 美, which likely contributes the sound ビ and may also suggest the idea of a 'beautiful' or useful metal.
The left side 金 means metal, and the right side 美 means beauty. Picture a beautiful, lightweight metal: magnesium.
For ビ, imagine a bee (ビ) buzzing around a beautiful magnesium flower: bee -> ビ, and the metal shines beautifully.