sedimentary
Chert (Yellow Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Yellowish-brown to tan; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
- Hardness
- 6
- Color
- Yellowish-brown to tan
- 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: Yellowish-brown to tan; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.
Formation & geological history
Formed via the accumulation of silica-rich organic remains or through the chemical precipitation of silica in sedimentary environments. Its age can range from Precambrian to recent geological eras.
Uses & applications
Used historically for stone tools due to its sharp edges when broken. Frequently used today for decorative landscaping, lapidary work, and as a semi-precious gemstone in jewelry when it is high-quality jasper.
Geological facts
Yellow jasper is a variety of chert colored by iron inclusions (goethite). It has been used by humans for hundreds of thousands of years to create arrowheads and scrapers because of its predictable fracture pattern.
Field identification & locations
Identify in the field by its smooth, waxy texture and distinctive shell-like (conchoidal) fracture pattern when chipped. It is commonly found in riverbeds, desert pavements, and as nodules in limestone or chalk deposits.
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