Calamites Stem Impression
Calamites cf. suckowii • Plant body fossil (compression/impression); Invertebrate-era flora
Geological Period
Carboniferous (specifically Pennsylvanian Subperiod)
Estimated Age
298 to 325 million years
Preservation Type
Carbonaceous compression or pith cast impression with iron-oxide (limonite/hematite) staining.
Condition Assessment
Fair to Good. The ribbing is distinct, but the specimen is a fragmentary piece lacking nodal junctions or branching points.
Taxonomic Classification
Phylum: Pteridophyta, Class: Equisetopsida, Order: Equisetales, Family: Calamitaceae, Genus: Calamites
Morphological Description
Specimen exhibits parallel longitudinal ribbing (striae) and grooves characteristic of the internal casting of pith cavities. The ribs are broad and flattened, separated by narrow furrows without visible nodes (joint segments), suggesting this is a fragmentary section of a larger trunk.
Rock Matrix
Sideritic ironstone or ferruginous shale, common in coal-bearing sequences.
Formation & Location
Likely sourced from the Mazon Creek Formation (Illinois, USA), the Coal Measures of South Wales/Northern England, or the Appalachian Basin (carboniferous strata).
Size & Dimensions
Approximately 5-8 cm in length; representing a partial section of a plant that could originally reach 30 meters in height.
Value & Rarity
Estimated Market Value
$15.00 - $35.00 USD
Auction Estimate
$20.00 - $50.00 USD (as part of a bulk natural history lot)
Rarity Assessment
Common. Calamites fragments are among the most frequently found plant fossils in Carboniferous coal-mining regions globally.
Scientific Significance
Provides evidence of Carboniferous 'coal swamp' ecosystems where arborescent horsetails were dominant canopy or sub-canopy species, contributing significantly to global coal peat formation.
Preparation Recommendations
No invasive preparation needed. Store in a low-humidity environment to prevent further oxidation or 'shale rot'. Surface dust can be removed with a soft dry brush.
Notable Features
Heavy mineralization of the matrix gives it a reddish-brown hue typical of iron-rich sedimentary deposits. The longitudinal ribs are well-defined, showing the internal structure of the plant's hollow stem.