sedimentary
Chert (Yellow Jasper)
Microcrystalline Quartz (SiO2)
Mohs hardness of 6.5-7. Opaque to translucent. Waxy to dull luster. Conchoidal (shell-like) fracture. Trigonal crystal system. Specific gravity of 2.6-2.7. Color is yellowish-brown due to iron oxide inclusions.
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness of 6.5-7. Opaque to translucent. Waxy to dull luster. Conchoidal (shell-like) fracture. Trigonal crystal system. Specific gravity of 2.6-2.7. Color is yellowish-brown due to iron oxide inclusions.
Formation & geological history
Formed by the precipitation of silica from groundwater or within deep-sea marine sediments. This microcrystalline variety often forms as nodules or bedded deposits within limestone or sandstone formations.
Uses & applications
Historically used for making stone tools (arrowheads). Modern uses include tumbled stones for jewelry, lapidary art, and aquarium decor due to its chemical stability.
Geological facts
Jasper and chert have been used by humans for over a million years to create sharp-edged tools. Yellow jasper is specifically associated with various folklore traditions as a stone of protection and solar energy.
Field identification & locations
Identify in the field by its hardness (scratches glass), waxy feel, and smooth curved (conchoidal) breaks. Often found in riverbeds or coastal deposits.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
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
sedimentary