sedimentary
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Hardness: 7 (Mohs), Color: Tan, brown, creme; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Specific Gravity: 2.6
- Hardness
- 7 (Mohs), Color: Tan, brown, creme
- Color
- Tan, brown, creme
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Chert (River Pebble) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs), Color: Tan, brown, creme; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Specific Gravity: 2.6
Formation & geological history
Formed via the accumulation of silica-rich organic remains or chemical precipitation in groundwater; this specimen has been water-worn into a smooth pebble shape.
Uses & applications
Historically used for stone tools/weapons; currently used for landscaping, road construction aggregate, and as common collector items.
Geological facts
Chert is so durable that it often survives long-distance transport in rivers while other rocks break down, which is why it is ubiquitous in gravel pits and riverbeds.
Field identification & locations
Identify by its hardness (scratches glass), waxy feel, and smooth surfaces despite its irregular shape. Common in riverbeds and glacial till globally.
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