sedimentary

Banded Chert

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 Mohs; Color: Brown, tan, and creamy white bands; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Brown, tan, and creamy white bands
Luster: Waxy to dull

Identified June 24, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, tan, and creamy white bands; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation within sedimentary layers. This specific piece shows distinct iron-rich staining resulting in the brown banding.

Uses & applications

Historically used for stone tools and weapons due to its conchoidal fracture. Today used primarily for decorative purposes, lapidary work, and landscaping.

Geological facts

Banded chert is often associated with Precambrian formations like Banded Iron Formations (BIFs), which are among the oldest rocks on Earth.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), conchoidal fracture patterns, and fine-grained, smooth texture. Often found in limestone or dolomite beds.