TgTosPr Isaiah.1:22 :עובדייך הוון דמיין מלקדמין היך כספא סנין איתהפכתא להישתכחא בך פסולא‏ : your works were formerly like fine silver, but you have changed so that dross is now present in you
See the entire entry for pāsōlā n.f. slag, dross