Annularia

About it

Star-like whorls of narrow leaves around the joints of Calamites shoots, like little flowers on the shale. Common in Pennsylvanian coal-measure shales and Mazon Creek nodules.

Type

Fossil (plant)

Group

Horsetail (plant)

Colours

black, brown, silvery white

Transparency

opaque

Periods

Carboniferous, Permian

Typical values: real specimens vary. For more, see mindat.org.