shale (en)

(noun) a fissile rock that is formed by the consolidation of clay, mud, or silt, has a finely stratified or laminated structure, and is composed of minerals essentially unaltered since deposition / (noun) a crude dark oil obtained from oil shale by heating / (noun) a rock (as shale) from which oil can be recovered by distillation

—p.186 Up the Mountain Coming Down Slowly (141) by Dave Eggers 6 years, 11 months ago