Oil shale

About it

Fine-grained, often finely layered rock rich in kerogen; rich pieces burn with a smoky flame. The Green River Formation of Colorado, Utah, and Wyoming holds vast deposits and famous fossil fish.

Type

Rock (sedimentary)

Group

Sedimentary (organic)

Lustre

dull, earthy

Colours

brown, grey, black

Transparency

opaque

Cleavage and fracture

splits along bedding

Typical values: real specimens vary. For more, see mindat.org.