The impurities of silver separated from the one in the process of melting (Prov. 25:4; 26:23; Ps. 119:119). It is also used to denote the base metal itself, probably before it is smelted, in Isa. 1:22, 25.
Dross
Dross is what rises to the top when silver is melted, the waste that has to be skimmed away. Proverbs 25:4 uses it as a plain fact of craft: “Take away the dross from the silver, and there shall come forth a vessel for the finer.” The prophets turn it into a sad image. “Thy silver is become dross,” Isaiah says of Jerusalem, and Ezekiel hears God say the house of Israel is dross in his furnace. Elsewhere the dross is the wicked, and the psalmist loves God’s word all the more. Isaiah 1 begins with the charge.
6 verses
Psalms
Psalms 119:119
Thou puttest away all the wicked of the earth like dross: therefore I love thy testimonies.
Proverbs
Proverbs 25:4
Take away the dross from the silver, and there shall come forth a vessel for the finer.
Proverbs 26:23
Burning lips and a wicked heart are like a potsherd covered with silver dross.
Isaiah
Isaiah 1:22
Thy silver is become dross, thy wine mixed with water:
Ezekiel
Ezekiel 22:18
Son of man, the house of Israel is to me become dross: all they are brass, and tin, and iron, and lead, in the midst of the furnace; they are even the dross of silver.
Ezekiel 22:19
Therefore thus saith the Lord GOD; Because ye are all become dross, behold, therefore I will gather you into the midst of Jerusalem.
From Easton's Bible Dictionary
Matthew George Easton, 1897