"Microtomes and Microtome Assemblies"

Red, medium, to coarse-grained iron oxide cement; shows hematite bands.

White and black bands of quartz, feldspar, and biotite; typical foliation.

1 pound of black sand packaged in a heat-sealed bag.

Pink and gray bands, with biotite; shows good foliation.

Gray to brown mudstone with abundant silt.

Fightly cemented, medium-to-coarse quartz grains.

Black, soft; most widely mined.

Gray to buff, with numerous ooliths and fossil fragments.

Light gray, fine small clasts.

Dense and massive.

Hematite-cemented quartz; orthoquartzite.

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.

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