DROSS. The refuse in impure metals that is generally separated by melting, when the dross rises to the top and may be skimmed off. It is used figuratively of what is worthless (Ps.119.119; Isa.1.22, Isa.1.25; Ezek.22.18-Ezek.22.19).
כֶּ֣סֶף ֭סִיגִים “silver of dross” (Prov 26:23, mg.) has been rightly altered by the RSV to כספסיגים, “as glaze.” Ugaritic spsg “whiteness” or “white glaze” provided a clue to this meaning.
W. F. Albright, BASOR 98 (1945), 24, 25.
International Standard Bible Encyclopedia (1915)
The refuse of smelting of precious metal (Pr 25:4; 26:23); used figuratively of what is base or worthless (Isa 1:22,25; Eze 22:18,19; Ps 119:119).