Calamites (Horsetail) Stem Fragment
Calamites cf. suckowii • Plant body fossil; internal pith cast
Geological Period
Carboniferous (Pennsylvanian sub-period)
Estimated Age
299 to 318 million years
Preservation Type
Pith cast (sedimentary infill). The hollow center of the plant stem filled with sediment which then lithified, preserving the internal texture of the vascular tissue.
Condition Assessment
Fair to Good. The longitudinal ribbing is clear, though the specimen is fragmented and lacks complete nodal details or attachment points.
Taxonomic Classification
Kingdom: Plantae, Division: Pteridophyta, Class: Equisetopsida, Order: Equisetales, Family: Calamitaceae, Genus: Calamites
Morphological Description
The specimen displays characteristic longitudinal ribbing (striations) parallel to the stem axis. These vertical ridges represent the internal pith of a woody, bamboo-like plant. There is a visible node (the horizontal line/break) where lateral branches or leaves once attached.
Rock Matrix
Ferruginous sandstone/siltstone with iron oxide staining (limonite/hematite), common in terrestrial coal-shale sequences.
Formation & Location
Potentially the Mazon Creek (Illinois, USA), Coal Measures (UK), or various Carboniferous formations in the Appalachian Basin (USA).
Size & Dimensions
Approximately 5-7 cm in length; consistent with mid-sized branch fragments of the arborescent Calamites, which could grow up to 30 meters tall.
Value & Rarity
Estimated Market Value
$10 - $25 USD
Auction Estimate
$15 - $40 USD (as part of a bulk plant fossil lot)
Rarity Assessment
Common. Calamites fragments are ubiquitous in Carboniferous-aged coal and deltaic deposits worldwide.
Scientific Significance
Provides evidence of the 'Coal Forest' swamp ecosystems of the Paleozoic. These giant horsetails were major contributors to the biomass that eventually formed global coal deposits.
Preparation Recommendations
No intensive preparation needed. Should be kept in a dry environment to prevent further oxidation of the iron minerals. Natural soft brush cleaning is sufficient.
Notable Features
Distinctive ferruginous (reddish-brown) coloration suggesting an oxygen-rich secondary mineralization environment during or after fossilization.