sedimentary
Calamites
Calamites (Pith cast fossil)
Hardness: 3-5 (varies by mineral replacement), Color: Dark grey to charcoal, Luster: Dull/Earthy, Structure: Segmented cylindrical ribbing with transverse nodes.
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Physical properties
Hardness: 3-5 (varies by mineral replacement), Color: Dark grey to charcoal, Luster: Dull/Earthy, Structure: Segmented cylindrical ribbing with transverse nodes.
Formation & geological history
Formed as internal sediment molds (pith casts) of giant horsetail tree stems from the Carboniferous Period (approx. 360-300 million years ago) in swampy, coal-forming environments.
Uses & applications
Primarily for scientific research, educational fossil collections, and museum display. Contributed to the formation of major coal beds.
Geological facts
Calamites were prehistoric relatives of modern horsetails that grew up to 30-50 meters tall. The fossils are usually segments of the trunk rather than the whole plant.
Field identification & locations
Identified by parallel vertical ridges and horizontal joint lines resembling bamboo. Found commonly in shale or sandstone layers near coal mines in North America and Europe.
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