sedimentary
Chert
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Brown with white veins; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
- Hardness
- 6
- Color
- Brown with white veins
- Luster
- Dull to waxy
Identified More sedimentary →
Explore Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 Mohs; Color: Brown with white veins; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
Formation & geological history
Formed primarily as chemical precipitates or through the replacement of limestone by silica-rich fluids. This specimen is a water-worn river pebble or beach stone.
Uses & applications
Historically used for stone tools and weapons (flintknapping); currently used for masonry, road construction, and as decorative river stones.
Geological facts
Chert is one of the most durable sedimentary rocks. When broken, it produces sharp edges which made it the primary material for prehistoric arrowheads and scrapers.
Field identification & locations
Identified in the field by its extreme hardness (scratches glass), smooth texture, and waxy luster. Common in riverbeds and limestone regions.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary