shale

noun 0.775

oil shale

noun 0.738

shale oil

noun 0.727

mudstone

noun 0.631

schist

noun 0.624

black mud

noun 0.617

brown coal

noun 0.612

blueschist

noun 0.603

siltstone

noun 0.577

kerogen

noun 0.573

phyllite

noun 0.568

argillite

noun 0.558

coal black

noun 0.556

lignite

noun 0.556

coal seam

noun 0.547

oil sand

noun 0.545

metasedimentary

noun 0.542

greywacke

noun 0.538

carbonaceous chondrite

noun 0.536

sulfide

noun 0.535

black carbon

noun 0.535

sedimentary rock

noun 0.534

humate

noun 0.532

tar sand

noun 0.532

red mud

noun 0.532

rock oil

noun 0.532

coal tar

noun 0.529

coal bed

noun 0.528

asphalt shingle

noun 0.525

iron sulphide

noun 0.525

sapropel

noun 0.522

greensand

noun 0.520

coal oil

noun 0.520

carbon black

noun 0.520

ball clay

noun 0.517

mineral coal

noun 0.515

chalkland

noun 0.513

sedimentary basin

noun 0.512

slate

noun 0.512

arkose

noun 0.512

sulphide

noun 0.512

graptolite

noun 0.511

slate gray

noun 0.510

chromitite

noun 0.510

gilsonite

noun 0.510

black gold

noun 0.509

red chalk

noun 0.508

anthracite

noun 0.508

graphite

noun 0.506

stishovite

noun 0.506

lawsonite

noun 0.506

black phosphorus

noun 0.505

biochar

noun 0.504

marlstone

noun 0.504

amphibolite

noun 0.503

chlorite

noun 0.503

serpentinite

noun 0.503

sedimentary

noun 0.502

humic acid

noun 0.502

black smoker

noun 0.502

blue-black

noun 0.501

coalbed methane

noun 0.501