scoria
Concise Oxford English Dictionary © 2008 Oxford University Press:
scoria /ˈskɔːrɪə/
▶noun (pl. scoriae /-rɪiː/)
- 1 basaltic lava ejected as fragments from a volcano, typically with a frothy texture.
- 2 slag separated from molten metal during smelting.
– derivatives
scoriaceous /-ˈeɪʃəs/ adjective.
scoriaceous /-ˈeɪʃəs/ adjective.
– origin ME: via L. from Gk skōria ‘refuse’, from skōr ‘dung’.
'scoria' also found in these Oxford entries:

