"Microtomes and Microtome Assemblies"

Dense and massive.

Hematite-cemented quartz; orthoquartzite.

Lustrous, black 'hard coal'.

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

Brownish black, intermediate stage between peat and bituminous coal.

Chlorite-mica with perfect slaty cleavage.

Typical green-gray, fissile, clay-rich.

White, very dark green, and very dark red to light red granoblastic intergrowth of wollastonite, diopside, and andradite.

Coarse, 'salt and pepper': dark pyroxene and light andesine. Provides perfect representation of an intermediate igneous rock.

Red-brown to gray, coarse-grained, containing feldspar and mica.