"Microtomes and Microtome Assemblies"

Black, soft; most widely mined.

Light gray, fine small clasts.

Dense and massive.

Hematite-cemented quartz; orthoquartzite.

Pure, large, transparent-to-translucent cleavages, Mohs’ hardness of 4.

Lustrous, black 'hard coal'.

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

Brownish black, intermediate stage between peat and bituminous coal.

Pale pink felsite, with small sanidine phenocrysts.

Gray to buff, with numerous ooliths and fossil fragments.