Answer: scoriae

AnswerCrossword Clue
SCORIAEWorthless residue from melted metals.
SCORIAELava and slag.
SCORIAEWaste materials
SCORIAESmeltery leavings
scoriaethe refuse, dross, or slag left after melting or smelting metal; scum
scoriaeugh vesicular cindery lava
scoriaethe refuse from melting of metals or reduction of ores slag
scoriaeSCORIA, the dross or slag from metal smelting