This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鉇 combines 金 (metal) with 㐌, but the exact historical development is uncertain. It may be a variant or rare character with a phono-semantic structure, but no clear origin is established.
With no clear meaning, focus on the shape: metal 金 beside 㐌, a rare component. Remember it as an uncommon kanji with a metal radical.
For シ, imagine a shiny (シ) metal object made of 金, but the exact use is unclear: shiny -> シ.