sedimentary
Chert (Jasper/Flint variety)
Silicon Dioxide (SiO2)
Hardness: 7 Mohs scale; Color: Brown, tan, reddish tones; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
- Hardness
- 7 Mohs scale
- Color
- Brown, tan, reddish tones
- Luster
- Waxy to vitreous
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 Mohs scale; Color: Brown, tan, reddish tones; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
Formation & geological history
Formed as nodules or layered deposits when microcrystalline quartz precipitates from watery solutions. It is common in limestone or chalk beds and can range from Precambrian to recent geological ages.
Uses & applications
Used historically for stone tools and arrowheads due to its sharp edges; used today as decorative stones, in lapidary work (jewelry), and for starting fires (flint).
Geological facts
Chert was one of the first materials used by early humans to create sophisticated tools. Because it breaks with conchoidal fractures, it creates edges sharper than a steel scalpel.
Field identification & locations
Identify in the field by its very smooth surface, waxy luster, and petal-shaped (conchoidal) chips or fractures. It can scratch glass and steel. Common globally in sedimentary rock outcrops.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone
Arenite
sedimentary