Sco·ri·a n.; pl. Scoriae
  1. The recrement of metals in fusion, or the slag rejected after the reduction of metallic ores; dross.
  2. Cellular slaggy lava; volcanic cinders.
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  scoria
       n : the scum formed by oxidation at the surface of molten metals
           [syn: slag, dross]
       [also: scoriae (pl)]