sedimentary
Calamites (Fossilized Horsetail)
Calamites suckowii (Family: Calamitaceae)
Hardness: 3-6 (depending on mineral replacement, often silica or calcite); Color: Gray, brown, or black; Luster: Dull to earthy; Structure: Cylindrical internal cast with vertical ribbing (striae) and horizontal nodes; Specific Gravity: 2.3-2.7.
- Color
- Gray, brown, or black
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-6 (depending on mineral replacement, often silica or calcite); Color: Gray, brown, or black; Luster: Dull to earthy; Structure: Cylindrical internal cast with vertical ribbing (striae) and horizontal nodes; Specific Gravity: 2.3-2.7.
Formation & geological history
Formed during the Carboniferous Period (approx. 300-360 million years ago). These are pith casts created when sediment filled the hollow centers of giant reed-like trees in swampy delta environments, which then underwent permineralization or petrifaction.
Uses & applications
Primarily used for geological education, paleontological research, and as collector specimens. Historically, the biomass of these plants contributed significantly to the formation of coal seams.
Geological facts
Calamites grew up to 30-50 meters tall, making them giant ancestors of modern horsetails (Equisetum). The ribbing seen on the fossil is actually an impression of the inner surface of the plant's hollow stem.
Field identification & locations
Identify by the distinctive longitudinal parallel ribs and occasional circular nodes (scars where branches grew). Commonly found in 'coal measures' or shale deposits in the Appalachian Mountains, UK, and Germany. Collectors should look for jointed sections in fine-grained sedimentary rock.
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