"Microtomes and Microtome Assemblies"

Dense and massive.

Hematite-cemented quartz; orthoquartzite.

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

Chlorite-bearing.

Black, soft; most widely mined.

Slaty cleavage; contains hematite.

Lustrous, black 'hard coal'.

Pale pink felsite, with small sanidine phenocrysts.

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

Brownish black, intermediate stage between peat and bituminous coal.

Unpolished metamorphic rock with silky lusture, red-brown colour, and clear parallel intergrown quartz crystals.

Gray to buff, with numerous ooliths and fossil fragments.

Gray, fine-grained, massive contact rock.

Chlorite-mica with perfect slaty cleavage.

Brownish gray, translucent.

Gray to white, coarse crystalline, carbonate rock.