scoria

Porous cinderlike fragments of dark lava.

The refuse of a smelted metal or ore; slag.

Dross; cinder; slag: a word of rather variable and indefinite meaning, generally used in the plural, and with reference to volcanic rocks. See scoriaceous.

A genus of geometrid moths, containing such as the black-veined moth, S. dealbata.

The recrement of metals in fusion, or the slag rejected after the reduction of metallic ores; dross.

Cellular slaggy lava; volcanic cinders.

the scum formed by oxidation at the surface of molten metals