sedimentary

Chert (Jaspery variety)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Tan, beige, and grayish-white. Luster: Waxy to dull. Structure: Cryptocrystalline/Microcrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

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

Identified July 9, 2026More sedimentary →

Explore Chert (Jaspery variety) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Tan, beige, and grayish-white. Luster: Waxy to dull. Structure: Cryptocrystalline/Microcrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation within sedimentary rock layers, often limestone or chalk. Commonly found in ancient marine environments.

Uses & applications

Historically used for stone tools (arrowheads/scrapers) due to sharp edges; currently used in construction aggregate and as a semi-precious stone for lapidary work.

Geological facts

Chert was one of the most important minerals for early humans because of its ability to fracture with extremely sharp, glass-like edges. It is chemically identical to quartz but contains impurities.

Field identification & locations

Identify by its hardness (will scratch glass), smooth waxy feel on broken surfaces, and distinct conchoidal (shell-like) fracture patterns. Frequently found in stream beds and road cuts.