sedimentary
Chert / Jasper
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs scale. Color: Reddish-brown, tan, and cream-colored banding or mottling. Luster: Waxy to dull. Fracture: Conchoidal to uneven. Microcrystalline quartz structure.
- Hardness
- 6
- Color
- Reddish-brown, tan, and cream-colored banding or mottling
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs scale. Color: Reddish-brown, tan, and cream-colored banding or mottling. Luster: Waxy to dull. Fracture: Conchoidal to uneven. Microcrystalline quartz structure.
Formation & geological history
Formed by precipitation of silica-rich fluids within sedimentary rock formations (such as limestone or shale) or through diagenetic replacement of organic material.
Uses & applications
Historically used for knapping arrowheads and stone tools due to conchoidal fracture. Modern uses include lapidary arts, landscaping, and aggregate.
Geological facts
Reddish coloration in chert or jasper is typically caused by inclusions of iron oxides (hematite or goethite). It is exceptionally durable and weather-resistant.
Field identification & locations
Identify by its hardness (scratches glass readily), smooth conchoidal fracture edges, waxy feel, and dense microcrystalline texture. Commonly found in sedimentary outcrops, river beds, and gravel deposits worldwide.
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