noun, noun which may take the genitive case particle 'no'
brown coal; lignite
Technical term for a low-grade coal; used in geology, energy, and industrial contexts.
褐炭は石炭の中でも発熱量が低い。
Lignite has a low calorific value among coals.
この地域では褐炭の採掘が行われている。
Lignite mining is carried out in this region.
Compound of 褐 (brown) and 炭 (coal/charcoal). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning 'brown coal'.