sedimentary
Chert / Flint (Brecciated or Fossiliferous Limestone with Silicification)
Sedimentary cryptocrystalline quartz (SiO2)
Hardness: 7 on the Mohs scale. Color: White with reddish-brown patches (due to iron oxide staining). Luster: Waxy to vitreous. Crystal structure: Microcrystalline / cryptocrystalline quartz (chalcedony). Fracture: Conchoidal. Specific gravity: 2.60 to 2.65.
- Hardness
- 7 on the Mohs scale
- Luster
- Waxy to vitreous
Identified More sedimentary →
Explore Chert / Flint (Brecciated or Fossiliferous Limestone with Silicification) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on the Mohs scale. Color: White with reddish-brown patches (due to iron oxide staining). Luster: Waxy to vitreous. Crystal structure: Microcrystalline / cryptocrystalline quartz (chalcedony). Fracture: Conchoidal. Specific gravity: 2.60 to 2.65.
Formation & geological history
Formed through the chemical precipitation of silica from aqueous solutions or the replacement of calcium carbonate in limestone by silica-rich fluids over millions of years in marine environments during the Mesozoic or Paleozoic eras.
Uses & applications
Historically used by indigenous peoples and ancient humans for making stone tools, arrowheads, and blades due to its conchoidal fracture. Often collected as a specimen by amateur geologists and rockhounds.
Geological facts
The distinct color pattern comes from iron oxide (rust) permeating parts of the matrix while other areas remain as pure white limestone or chalcedony. This particular specimen has been naturally tumbled and smoothed by water action in a stream or beach environment.
Field identification & locations
Can be identified in the field by its high hardness (scratches glass easily), smooth water-worn surface, waxy luster, and distinctive conchoidal fracture edges. Commonly found in riverbeds, glacial tills, and sedimentary rock formations worldwide.
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