sedimentary
Chert
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Tan, beige, brown; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Tan, beige, brown
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 Mohs; Color: Tan, beige, brown; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Forms primarily as nodules or beds in sedimentary rocks through the accumulation of silica-rich organic remains or chemical precipitation. Found in various geological eras.
Uses & applications
Historically used for stone tools due to sharp edges; currently used in construction as road metal and in lapidary work for tumbled stones and cabochons.
Geological facts
Flint is a dark variety of chert. It has been used since the Stone Age for making arrowheads and spear points because of the way it fractures into sharp edges.
Field identification & locations
Identified by its waxy appearance, extreme hardness (scratches glass), and distinctive shell-like (conchoidal) fracture pattern. Common in limestone deposits.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary