sedimentary

Chert (Jasper variation)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: Brownish-tan with hints of red (jasper-like), Luster: Waxy to dull, Crystal Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified May 22, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale), Color: Brownish-tan with hints of red (jasper-like), Luster: Waxy to dull, Crystal Structure: Cryptocrystalline, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolarians or diatoms) or by chemical precipitation in marine or groundwater environments; often found in nodules or bedded layers.

Uses & applications

Historically used for stone tools (arrowheads/scrapers) due to its sharp conchoidal edges; currently used for lapidary work, landscaping, and gravel.

Geological facts

Chert has played a vital role in human evolution as one of the primary materials for 'Stone Age' technology. This specific specimen shows a waxy patina typical of river-worn or weathered silica.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), waxy texture, and the way it breaks into smooth, curved shell-like patterns (conchoidal fracture). Common in limestone regions.