sedimentary
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs), Color: Tan, brown, creme; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Specific Gravity: 2.6
- Hardness
- 7 (Mohs), Color: Tan, brown, creme
- Color
- Tan, brown, creme
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 (Mohs), Color: Tan, brown, creme; Luster: Waxy to dull; Structure: Cryptocrystalline; Fracture: Conchoidal; Specific Gravity: 2.6
Formation & geological history
Formed via the accumulation of silica-rich organic remains or chemical precipitation in groundwater; this specimen has been water-worn into a smooth pebble shape.
Uses & applications
Historically used for stone tools/weapons; currently used for landscaping, road construction aggregate, and as common collector items.
Geological facts
Chert is so durable that it often survives long-distance transport in rivers while other rocks break down, which is why it is ubiquitous in gravel pits and riverbeds.
Field identification & locations
Identify by its hardness (scratches glass), waxy feel, and smooth surfaces despite its irregular shape. Common in riverbeds and glacial till globally.
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