fossil

Fossiliferous Chert Nodule

SiO2 (Microcrystalline Quartz) with fossil inclusions

Hardness: 6.5-7 on the Mohs scale. Color: Tan, beige, grey, and off-white. Luster: Waxy to dull. Structure: Microcrystalline with embedded marine invertebrate fossil structures (such as crinoid stem fragments or bryozoans). Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Tan, beige, grey, and off-white
Luster: Waxy to dull

Identified July 26, 2026More fossil →

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Physical properties

Formation & geological history

Formed during the Paleozoic era in shallow marine environments where silica replaced carbonate sediment and organism remains inside limestone matrixes, later weathered out into rounded river nodules.

Uses & applications

Used historically for stone tool making (flint knapping) due to conchoidal fracture. Today collected as fossil and mineral specimens or used in landscaping.

Geological facts

Chert often preserves minute details of ancient marine life. The faint linear impression visible on the upper part of the stone represents a stem segment from an ancient crinoid (sea lily) or similar Paleozoic marine organism.

Field identification & locations

Identified by its extreme hardness (scratches glass), waxy luster, smooth river-worn exterior, and distinct embedded marine fossil molds or casts. Common in gravel deposits, riverbeds, and limestone outcrops worldwide.

Other fossil specimens

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Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Sedimentary Outcrop (Sandstone/Shale)

Sedimentary bedrock formation (variable composition)

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Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

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Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

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Fossiliferous Limestone

Limestone with embedded fossil cross-section

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Fossiliferous Limestone

Fossiliferous Calcilutite / Biomicrite

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