sedimentary
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Hardness: 7; Color: Mottled brown, grey, and tan; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 7
- Color
- Mottled brown, grey, and tan
- Luster
- Dull to waxy
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Physical properties
Hardness: 7; Color: Mottled brown, grey, and tan; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed in marine environments through the accumulation of silica-rich organic remains or chemical precipitation; this specimen is water-worn and weathered.
Uses & applications
Historically used for making stone tools; currently used in construction aggregate and as decorative landscaping stones.
Geological facts
Chert is essentially the same material as flint, but the term 'flint' is usually reserved for dark nodules found in chalk or limestone. It is one of the most durable common rocks.
Field identification & locations
Identify by its high hardness (scratches glass) and smooth, rounded water-worn texture. It is ubiquitous in riverbeds and glacial till throughout North America and Europe.
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Chert Breccia
Brecciated Chert (Microcrystalline Silica)
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