sedimentary
Chert Nodule
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 Mohs scale. Color: Grayish-brown with waxy to dull luster. Structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.
- Hardness
- 7 Mohs scale
- Color
- Grayish-brown with waxy to dull luster
Identified More sedimentary →
Explore Chert Nodule in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 Mohs scale. Color: Grayish-brown with waxy to dull luster. Structure: Cryptocrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.
Formation & geological history
Formed in marine sedimentary environments through the precipitation of silica from seawater or the accumulation of siliceous skeletal remains (like radiolaria) within limestone or chalk beds.
Uses & applications
Historically used for stone tools (flint knapping). Today used as laboratory mortar and pestles, road material, or as decorative river rock.
Geological facts
Chert is so durable that it often remains as pebbles in stream beds long after the surrounding limestone has eroded away. Varieties include flint, jasper, and agate.
Field identification & locations
Identify by its extreme hardness (scratches glass), waxy luster when freshly broken, and smooth, rounded water-worn exterior often found in riverbeds.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary