sedimentary

Banded Chert / Cryptocrystalline Quartz

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs). Color: Multi-colored bands (teal, white, reddish-brown). Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Multi-colored bands (teal, white, reddish-brown)
Luster: Waxy to vitreous

Identified July 9, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs). Color: Multi-colored bands (teal, white, reddish-brown). Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).

Formation & geological history

Formed from the accumulation of silica-rich microfossils or chemical precipitation from hydrothermal fluids in marine or volcanic environments. The colors reflect mineral impurities like iron (red) and chlorite or copper silicates (green/teal).

Uses & applications

Collecting, lapidary use (cabbing and polishing), and historically used for stone tools due to its sharp conchoidal edges.

Geological facts

This specimen displays distinct primary layering known as banding, which often represents changes in sediment deposition or fluid chemistry over time.

Field identification & locations

Identified by its extreme hardness (cannot be scratched by steel), waxy feel, and sharp, shell-like fracture edges. Found worldwide in sedimentary nodules or bedded layers.