scoria
/ˈskɔːrɪə
/noun (plural scoriae /ˈskɔːrɪiː/) [mass noun]
1Basaltic lava ejected as fragments from a volcano, typically with a frothy texture: chunks of black scoria [count noun]: the village lay half silted up under black scoriae and dust...
- They cut steps in the frozen snow and made good progress along a ridge of ‘rugged scoriae’ which took them to the summit.
- Small vesicular pieces of volcanic material, scoria, collect around the vent to form a cinder cone.
- Alluvial, colluvial or chemically formed gravel, clayey gravel, sandstone, limestone, tuff, scoria are examples of marginal materials.
2Slag separated from molten metal during smelting: the scoria has been expelled completely from the mercury
Derivatives
scoriaceous
- The fine-grained ash groundmass contains equal proportions of scoriaceous tachylite and palagonite with basaltic lithic fragments.
- On the western side of the mesa, black hornblende xenocrysts several centimeters in size are also found in a scoriaceous, agglomeratic portion of the lava flow.
- Amygdaloidal cavities are located immediately below the uppermost scoriaceous part of the second flow, near its contact with the overlying flow.
Origin
Late Middle English (denoting slag from molten metal): via Latin from Greek skōria 'refuse', from skōr 'dung'. The geological term dates from the late 18th century.