Silicified Coral Fragment
Incertae sedis; cf. Lithostrotionella or Syringopora depending on internal structure • Body fossil (Invertebrate); Permineralized/replaced colonial coral
Geological Period
Likely Carboniferous to Permian
Estimated Age
250 - 350 million years
Preservation Type
Silicification (Replacement); The original calcium carbonate skeleton has been entirely replaced by microcrystalline quartz/chalcedony.
Condition Assessment
Fair to Good; the specimen is a weathered fragment with significant conchoidal fracturing and loss of external diagnostic features.
Taxonomic Classification
Phylum: Cnidaria, Class: Anthozoa, Order: Rugosa or Tabulata
Morphological Description
The specimen exhibits a dense, waxy luster consistent with silica replacement (chalcedony). Visible are remnants of corallites (individual tubes) appearing as faint circular or hexagonal outlines on the fractured surfaces. The structure is massive/sub-massive with secondary vugs or small cavities.
Rock Matrix
The matrix is largely inseparable from the fossil due to complete mineral replacement, likely originating from a limestone or cherty limestone setting.
Formation & Location
Commonly found in the Mississippian/Pennsylvanian formations of the Central United States (e.g., Keokuk Limestone) or similar marine deposits globally.
Size & Dimensions
Approximately 6-8 cm in length; typical for a hand-sample fragment of a larger reef-building colony.
Value & Rarity
Estimated Market Value
$10 - $25 USD
Auction Estimate
$15 - $30 USD (as part of a bulk natural history lot)
Rarity Assessment
Common; silicified coral fragments are abundant in Paleozoic limestone regions and frequently found as surface float.
Scientific Significance
Provides evidence of ancient reef-building environments and high-energy shallow marine paleoecology. Silicified fossils are important for understanding secondary mineralization processes.
Preparation Recommendations
No chemical preparation needed due to silica hardness. Light polishing could enhance the visibility of internal corallite structures. Store in a dry environment.
Notable Features
Features high-quality chalcedony replacement and distinct conchoidal fracture patterns; contains small internal druzy quartz pockets in center vugs.