"Freeze-Dried Specimens"

Brownish black, intermediate stage between peat and bituminous coal.

Gray to brown mudstone with abundant silt.

Gray and poorly sorted, with a gritty texture.

Gray to buff, with numerous ooliths and fossil fragments.

Black, soft; most widely mined.

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

Light gray, fine small clasts.

Dense and massive.

Hematite-cemented quartz; orthoquartzite.

Typical green-gray, fissile, clay-rich.

Gray with line crinoid columnal fragments.

Gray to tan clastic rock made of silt sized particles.

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

Compact Plant Fiber Masses.

Black, fissile; commonly with carbonized fossil plant impressions.

Light gray, earthy.