sedimentary
Banded Chert (Jasper/Agate)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs), Color: Multicolored bands of green, teal, and earth tones, Luster: Waxy to vitreous, Structure: Cryptocrystalline, Fracture: Conchoidal
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs), Color: Multicolored bands of green, teal, and earth tones, Luster: Waxy to vitreous, Structure: Cryptocrystalline, Fracture: Conchoidal
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation from sea water in low-energy environments, often during the Paleozoic or Mesozoic eras.
Uses & applications
Used for ornamental jewelry (cabochons), lapidary art, and historically for stone tools due to its sharp conchoidal fracture.
Geological facts
This specific piece is likely a type of 'fancy jasper' or ocean jasper variety; it shows distinct layering known as rhythmic bedding which records cycles in ancient marine environments.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife) and smooth, glass-like fracture surfaces. Common in river beds and coastal areas near volcanic activity.
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