Definition

1. Noun:
   • A porous, cinder-like form of solidified lava: Scoria is a type of volcanic rock that is dark-colored, vesicular (full of bubble holes), and relatively heavy. It forms when molten lava is thrown into the air and cools rapidly, trapping gas bubbles inside.
   • The slag or dross formed on the surface of molten metal: In metallurgy, scoria refers to the waste material or oxidized impurities that rise to the top of molten metal during smelting or refining.

Examples of Usage

• Noun (Volcanic Rock):
  • The path up the volcano was covered in sharp, red scoria.
  • Scoria is often used in landscaping and for drainage in garden beds.
• Noun (Metallurgical Waste):
  • The black scoria was skimmed from the surface of the molten iron.
  • Ancient slag heaps contain scoria from early metalworking.

Advanced Usage

• Geological Context: Scoria is distinguished from pumice, another vesicular volcanic rock, by its darker color, higher density, and larger, thicker-walled vesicles. It is a textural term for a highly vesicular basaltic or andesitic rock.
• Historical/Archaeological Context: The presence of scoria can be evidence of ancient metalworking sites, as it is a byproduct of smelting ores.

Variants and Related Words

• Scoriaceous (adj): Having the porous, rough texture of scoria.
  • The scoriaceous texture of the rock made it very lightweight.
• Cinder (n): A synonym for scoria, especially when referring to volcanic material. Also used for similar waste from coal combustion.
• Slag (n): A more common term for the glassy waste material from metal smelting, closely related to the metallurgical meaning of scoria.

Synonyms

• Cinder (for volcanic material)
• Lava rock (informal, for volcanic material)
• Dross (for metallurgical waste)
• Slag (for metallurgical waste)

Related Phrases/Idioms

There are no common idioms or phrasal verbs that use the word "scoria" directly. It is primarily a technical term.

Noun

1. the scum formed by oxidation at the surface of molten metals