sedimentary
Chert (Yellow or Brown Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 Mohs; Color: Tan, brown, ochre; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 6
- Color
- Tan, brown, ochre
- Luster
- Waxy to dull
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 Mohs; Color: Tan, brown, ochre; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or the chemical replacement of limestone/dolomite. It is found in deposits ranging from Precambrian to Cenozoic eras.
Uses & applications
Historically used for stone tools (flintknapping). Modernly used in geological collections, landscaping, and occasionally as a low-cost gemstone for cabochons.
Geological facts
Jasper is a variety of chert that gets its opaque color from high concentrations of iron oxides. It is so tough that it was one of the primary materials used by prehistoric humans to make arrowheads and scrapers.
Field identification & locations
Identify in the field by its waxy texture, smooth rounded edges (if river-worn), and conchoidal (shell-like) fracture patterns if chipped. It will easily scratch glass and steel.
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 (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary