the.com/slag
the molten garbage of metal-making, useful enough that it paves your roads.
steel byproductFloats atop molten metal, skimmed off as waste
road builderCrushed slag forms asphalt and concrete aggregate
British insultDoubles as slang for a promiscuous person
volcanic cousinSpongy lava rock shares the name scoria
glass cleanerAbsorbs impurities, purifying the molten metal below