sedimentary
Chert (Sea-worn Pebble)
Microcrystalline Quartz (SiO2)
Hardness: 7 (Mohs scale), Color: Brownish-tan to honey-yellow, Luster: Dull/Waxy, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6
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Physical properties
Hardness: 7 (Mohs scale), Color: Brownish-tan to honey-yellow, Luster: Dull/Waxy, Crystal Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.6
Formation & geological history
Formed by the precipitation of silica from seawater or through the replacement of limestone. This specimen has been rounded and smoothed by water action (abrasion) on a beach.
Uses & applications
Historically used for stone tools (flintknapping); currently used as gravel, decorative landscaping stones, or for rock tumbling.
Geological facts
This specific color variety of chert is often called 'Amber Chert' or 'Jasper' depending on regional naming. It is extremely chemically stable and resistant to erosion.
Field identification & locations
Identified by its smoothness, hardness (cannot be scratched by a steel blade), and waxy appearance when wet. Found commonly on beaches and in riverbeds worldwide.
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Chert Breccia
Brecciated Chert (Microcrystalline Silica)
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