Dross
DROSS, noun [G.]
1. The recrement or despumation of metals; the scum or extraneous matter of metals, thrown off in the process of melting.
2. Rust; crust of metals; an incrustation formed on metals by oxydation.
3. Waste matter; refuse; any worthless matter separated from the better part; impure matter.
The worlds glory is but dross unclean.