sedimentary
Chert / Flint Nodule
Microcrystalline quartz (SiO2)
Hardness: 7 on Mohs scale. Color: typically gray, brown, black, or white. Luster: waxy to dull. Crystal structure: microcrystalline/cryptocrystalline quartz (chalcedony). Cleavage: none, conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- typically gray, brown, black, or white
- Luster
- waxy to dull
Identified More sedimentary →
Explore Chert / Flint Nodule in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale. Color: typically gray, brown, black, or white. Luster: waxy to dull. Crystal structure: microcrystalline/cryptocrystalline quartz (chalcedony). Cleavage: none, conchoidal fracture.
Formation & geological history
Formed through the replacement of calcium carbonate by silica-rich solutions in marine environments (such as chalk or limestone beds) over millions of years.
Uses & applications
Historically used for making stone tools, arrowheads, and fire-starting (flint and steel). Modern uses include abrasives and road aggregates.
Geological facts
Chert and flint are chemically identical; the term 'flint' is often used for darker varieties found in chalk formations, while 'chert' refers to varieties found in limestone.
Field identification & locations
Identified by its hard conchoidal fracture and waxy luster. Common in sedimentary rock formations worldwide, particularly chalk and limestone deposits.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary