sedimentary

Calamites Fossil (Horsetail Stem)

Calamites (Genus), part of the class Equisetopsida

AI-generated identification · may be incorrect

Hardness: 3-6 (variable based on matrix); Color: Grey, tan, or reddish-brown; Luster: Dull/Earthy; Structure: Characterized by vertical ribs and horizontal nodes or joints (segments) where leaves or branches once attached.

Hardness: 3-6 (variable based on matrix)
Color: Grey, tan, or reddish-brown
Luster: Dull/Earthy

Identified March 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the process of permineralization or cast-and-mold fossilization in coal-forming swamp environments during the Carboniferous period (approx. 360 to 300 million years ago).

Uses & applications

Primarily for scientific study, educational collections, and as a decorative geological specimen for collectors.

Geological facts

Calamites were tree-like plants that grew up to 30 meters (100 feet) tall. They are the ancient ancestors of the modern-day horsetail (Equisetum). Most fossilized specimens are actually the internal casts of the hollow stem.

Field identification & locations

Identify in the field by looking for distinct parallel ribbing and bamboo-like segments in sandstone, shale, or coal beds. They are commonly found in the Appalachian region of the USA, the UK, and Europe. Collectors should look for clear vertical lines and well-preserved 'nodes'.