sedimentary
Chert (Iron-stained)
Chert (Silicon Dioxide, SiO2)
Hardness: 7 on Mohs scale; Color: tan to brown (iron-stained); Luster: dull to waxy; Structure: microcrystalline (no visible grains); Cleavage: none (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- tan to brown (iron-stained)
- Luster
- dull to waxy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: tan to brown (iron-stained); Luster: dull to waxy; Structure: microcrystalline (no visible grains); Cleavage: none (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed by the accumulation of siliceous remains of organisms (like diatoms) or by chemical precipitation from silica-rich fluids in sedimentary basins. Often found as nodules in limestone or chalk.
Uses & applications
Historically used for making stone tools (arrowheads). Industrially used in road construction as aggregate and as a low-cost lapidary material.
Geological facts
Chert is extremely durable and chemically stable. Due to its sharpness when fractured, it was one of the most important minerals for early humans in creating survival tools.
Field identification & locations
Identify in the field by its hardness (it will scratch glass) and its curved, shell-like (conchoidal) fracture pattern. It is common in riverbeds and limestone outcrops globally.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone
Arenite
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary