sedimentary
Brown Chert
Microcrystalline Quartz (SiO2)
Hardness: 7 (Mohs scale); Color: Brown to tan; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Brown to tan
- Luster
- Waxy to vitreous
Identified More sedimentary →
Explore Brown Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: Brown to tan; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed in sedimentary environments via the accumulation of siliceous remains of organisms or chemical precipitation from groundwater. Most specimens range from hundreds of millions to billions of years old.
Uses & applications
Historically used for stone tools and fire-starting. Currently used as road ballast, decorative landscaping stone, and in some gemstone polishing.
Geological facts
Chert is so hard it can scratch steel and was used by ancient civilizations for arrowheads and scrapers due to its sharp, glass-like fracture edge.
Field identification & locations
Identified by its extreme hardness, waxy texture, and smooth curved fractures. Common in riverbeds and limestone outcrops worldwide.
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