sedimentary
Chert (Arrowhead Point)
Microcrystalline Quartz (SiO2)
Hardness 7 on Mohs scale, orange-tan color, waxy to vitreous luster, conchoidal fracture, cryptocrystalline structure
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Physical properties
Hardness 7 on Mohs scale, orange-tan color, waxy to vitreous luster, conchoidal fracture, cryptocrystalline structure
Formation & geological history
Formed through the accumulation of silica-rich biogenic sediment or chemical precipitation in sedimentary rocks, often heat-treated and knapped by ancient peoples
Uses & applications
Historically used for tools, arrowheads, and spear points; currently collected as archaeological artifacts or lapidary display pieces
Geological facts
Chert splits with extremely sharp edges along conchoidal fracture lines, making it ideal for stone tool production across human history
Field identification & locations
Identified by its distinctive arrowhead shape with pressure-flaking marks along the edges and smooth conchoidal surfaces; found globally in limestone and chalk formations
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