sedimentary
Chert (Jasper variety)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs), Color: Reddish-brown, tan, and gray, Luster: Waxy to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
- Hardness
- 6
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: Reddish-brown, tan, and gray, Luster: Waxy to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments. This specimen shows significant rounding due to water transport in a river or coastal setting.
Uses & applications
Historically used for making stone tools (arrowheads). Modern uses include landscaping, lapidary work, jewelry (when highly colorful), and industrial abrasives.
Geological facts
The red coloring in this jasper-like chert is typically caused by iron inclusions (hematite). It is one of the most durable sedimentary rocks and can survive millions of years of erosion.
Field identification & locations
Identify by its hardness (it will scratch glass), its smooth waxy feel when wet, and its characteristic curved (conchoidal) fracture planes. Common in riverbeds and glacial tills worldwide.
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