sedimentary
Yellow Chert (Yellow Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Yellow to brownish-yellow; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 6
- Color
- Yellow to brownish-yellow
- Luster
- Waxy to dull
Identified More sedimentary →
Explore Yellow Chert (Yellow Jasper) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow to brownish-yellow; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed by the accumulation of siliceous remains of organisms or precipitation of silica-rich fluids in sedimentary basins. The yellow color is usually due to iron oxide impurities (goethite).
Uses & applications
Used historically for stone tools and arrowheads; currently used in jewelry (cabochons), as decorative garden stones, and as collectable mineral specimens.
Geological facts
Chert was one of the first materials used by early humans to create fire and sharp tools due to its conchoidal fracture which creates razor-sharp edges.
Field identification & locations
Identify by its waxy luster, smooth/curved fracture surfaces, and the fact that it can scratch steel or glass. Commonly found in limestone or dolomite beds.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Shale
Shale (clastic sedimentary rock)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Shale
Argillaceous sedimentary rock
sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary