sedimentary
Chert (Jasper / Flint variant)
Microcrystalline Quartz (SiO2)
Mohs hardness 6.5-7, dull to waxy/earthy luster, microcrystalline/cryptocrystalline texture, conchoidal fracture, reddish-brown to tan color due to iron oxide impurities.
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Physical properties
Mohs hardness 6.5-7, dull to waxy/earthy luster, microcrystalline/cryptocrystalline texture, conchoidal fracture, reddish-brown to tan color due to iron oxide impurities.
Formation & geological history
Formed by the precipitation of silica-rich solutions in sedimentary environments or through the replacement of limestone/chalk by microcrystalline silica over millions of years.
Uses & applications
Historically used for knapping arrowheads, blades, and strike-a-light flints. Commonly used today as decorative landscaping stone, aggregate, and for lapidary tumbling.
Geological facts
Chert was one of the earliest raw materials utilized by early humans to fashion sharp tools and weapons due to its predictable conchoidal fracture pattern.
Field identification & locations
Identified in the field by its hardness (scratches steel), smooth waxy-to-dull surface, and sharp-edged conchoidal fracturing. Extremely widespread in riverbeds and sedimentary regions globally.
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