sedimentary

Chert with Jasper/Quartz Inclusions

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Multi-colored with white, green, and reddish-brown bands; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Multi-colored with white, green, and reddish-brown bands
Luster: Waxy to vitreous

Identified June 11, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Multi-colored with white, green, and reddish-brown bands; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed primarily as a chemical precipitate or through the accumulation of siliceous remains of organisms in marine environments. The colors result from mineral impurities like iron (red) or chlorite (green) during the replacement process.

Uses & applications

Commonly used for lapidary work such as tumbling and cabochon making. Historically used by ancient cultures for tool making (arrowheads/scrapers) due to its sharp fracture edges.

Geological facts

This specimen appears to be a 'river rock' or tumbled piece where different phases of silica (jasper, agate, and chert) have intertwined. Chert is often tough enough to survive long-distance transport in river beds.

Field identification & locations

Identify in the field by its hardness (will scratch glass), smooth waxy texture when wet, and characteristic conchoidal fracture. Often found in gravel pits or riverbeds near sedimentary basins.