sedimentary
Chert (Yellow Jasper variant)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Yellow to brownish-yellow; Luster: Waxy to dull; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 6
- Color
- Yellow to brownish-yellow
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow to brownish-yellow; Luster: Waxy to dull; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed by the accumulation of siliceous remains of marine organisms (like radiolaria or diatoms) or by chemical precipitation from silica-rich fluids in sedimentary layers. It can be found in various geological ages ranging from Precambrian to Cenozoic.
Uses & applications
Historically used for stone tools and arrowheads; currently used as a semi-precious gemstone in jewelry (cabochons), lapidary art, and as decorative landscaping stone.
Geological facts
Yellow Jasper is often associated with the 'solar plexus chakra' in metaphysical circles. Chert is so durable that it is often found as smooth cobbles in riverbeds long after the surrounding rock has weathered away.
Field identification & locations
Identify in the field by its waxy luster and sharp, shell-like conchoidal fracture edges. It will easily scratch glass and cannot be scratched by a steel knife. Common in limestone or chalk beds and river gravels.
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