sedimentary
Chert (var. Jasper)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs); Color: Reddish-brown; Luster: Dull to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
- Hardness
- 6
- Color
- Reddish-brown
- Luster
- Dull to waxy
Identified More sedimentary →
Explore Chert (var. Jasper) 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: Reddish-brown; Luster: Dull to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
Formation & geological history
Formed from the accumulation of silica-rich microfossils or chemical precipitation in sedimentary basins. The reddish hue is due to iron oxide inclusions.
Uses & applications
Historically used for stone tools (arrowheads). Today used in jewelry, lapidary arts, and as landscaping stone.
Geological facts
Chert and jasper have been used by humans for millions of years to create sharp-edged tools due to their conchoidal fracturing.
Field identification & locations
Identify by its hardness (it will scratch glass), its waxy feel, and the way it breaks into smooth, curved surfaces. Common in riverbeds and ancient seafloors.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary