亜あ炭たん

noun, noun which may take the genitive case particle 'no'

lignite; brown coal

A type of low-grade coal; used in geological, industrial, or energy contexts.

• 亜あ炭たんは石せき炭たんの中なかでも炭たん化か度どが低ひくい。

  Lignite has a low degree of coalification among coals.