sedimentary
Chert (Flint / Jasper variant)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 on the Mohs scale; Color: Grey, brown, dark green to yellowish-brown with irregular weathering patinas; Luster: Waxy to sub-vitreous; Fracture: Conchoidal; Structure: Microcrystalline/cryptocrystalline aggregate.
- Hardness
- 6
- Luster
- Waxy to sub-vitreous
Identified More sedimentary →
Explore Chert (Flint / Jasper variant) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 on the Mohs scale; Color: Grey, brown, dark green to yellowish-brown with irregular weathering patinas; Luster: Waxy to sub-vitreous; Fracture: Conchoidal; Structure: Microcrystalline/cryptocrystalline aggregate.
Formation & geological history
Formed in marine environment sediments through the accumulation of siliceous organism remains (like radiolarians or diatoms) or by chemical precipitation of silica in limestones and chalk beds.
Uses & applications
Historically used for stone tools, arrowheads, and spark-striking flintlocks due to sharp conchoidal fractures. Modern uses include landscaping, aggregate, and lapidary carving.
Geological facts
Chert was one of the most critical rock types for early humans. Its ability to fracture with extremely sharp edges made it the primary material for prehistoric tools and weaponry.
Field identification & locations
Identified by its high hardness (scratches glass readily), smooth waxy feel, and sharp conchoidal fracture edges. Found abundantly in stream beds, gravel deposits, and limestone outcrops globally.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale
Argillaceous sedimentary rock
sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary