sedimentary
Chert (Jasper)
Cryptocrystalline Silicon Dioxide (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Opaque tan to brown; Luster: Dull to waxy; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.5-2.8
- Hardness
- 6
- Color
- Opaque tan to brown
- Luster
- Dull to waxy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Opaque tan to brown; Luster: Dull to waxy; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.5-2.8
Formation & geological history
Formed from the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Often found as nodules or stream-tumbled pebbles.
Uses & applications
Historically used for tools and arrowheads; currently used for decorative lapidary work, jewelry (cabochons), and landscaping.
Geological facts
Jasper is an opaque variety of chalcedony. It has been used since ancient times for cylinder seals and amulets due to its durability and ability to take a high polish.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel nail), smooth waxy texture, and conchoidal (shell-like) fracture edges. Commonly found in riverbeds and gravel 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