sedimentary
Chert (Jasper/Flint Pebble)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness 6.5-7 on Mohs scale; waxy to vitreous luster; smooth conchoidal fracture; gray-brown body with iron oxide streaking; trigonal microcrystalline structure.
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Physical properties
Hardness 6.5-7 on Mohs scale; waxy to vitreous luster; smooth conchoidal fracture; gray-brown body with iron oxide streaking; trigonal microcrystalline structure.
Formation & geological history
Formed through biochemical or chemical precipitation of silica in marine waters, subsequently rounded by river or glacial transport.
Uses & applications
Commonly used for lapidary tumbling, landscaping, decorative gravel, and historically for striking spark and stone tools.
Geological facts
Because of its high hardness and chemical resistance, chert often survives extensive weathering that destroys surrounding host rocks.
Field identification & locations
Identifiable by its smooth, water-worn exterior, extreme hardness (scratches glass), and fine-grained texture lacking visible crystals; common in stream beds and gravel pits.
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