sedimentary
Amber Chert (Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5–7 (Mohs scale); Color: Yellow-brown, tan, or honey; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6
- Hardness
- 6
- Color
- Yellow-brown, tan, or honey
- Luster
- Waxy to dull
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Yellow-brown, tan, or honey; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Common in marine limestone beds as nodules or replacement deposits.
Uses & applications
Used for making cutting tools historically; currently used in jewelry (cabochons), as an ornamental stone, and for specimen collecting.
Geological facts
Chert is so durable that it can survive long-distance transport in rivers and is often found as rounded river cobbles. It was one of the primary materials used by prehistoric humans for stone tools.
Field identification & locations
Identify by its waxy luster, extreme hardness (scratches glass), and shell-like (conchoidal) breakage patterns. Common in gravel pits or river beds where limestone has weathered away.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary