sedimentary
Chert Pebble
Chert (Microcrystalline Quartz, SiO2)
Hardness: 7 (Mohs scale), Color: Olive green to brownish-green, Luster: Waxy to vitreous when wet, Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6
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Physical properties
Hardness: 7 (Mohs scale), Color: Olive green to brownish-green, Luster: Waxy to vitreous when wet, Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6
Formation & geological history
Formed via the accumulation of silica-rich organic remains (like radiolarians or diatoms) or by chemical precipitation in marine environments. These pebbles are typically rounded by river or wave action over thousands of years.
Uses & applications
Historically used for stone tools and starting fires (flint); currently used in decorative landscaping, as river rock, or for rock tumbling.
Geological facts
Green chert often gets its color from chlorite or other mineral inclusions. It is one of the most durable sedimentary rocks and can withstand significant travel in high-energy river systems.
Field identification & locations
Identify in the field by its smooth texture, waxy appearance when wet, and ability to scratch glass. Commonly found in riverbeds, gravel pits, and coastal beaches.
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