sedimentary
Jasper / Chert
Microcrystalline Quartz (SiO2)
Hardness of 6.5 to 7 on the Mohs scale, earthy to vitreous luster, opaque to translucent transparency, conchoidal fracture, and colors ranging from reddish-brown to tan, white, and grey due to iron oxide impurities.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, earthy to vitreous luster, opaque to translucent transparency, conchoidal fracture, and colors ranging from reddish-brown to tan, white, and grey due to iron oxide impurities.
Formation & geological history
Forms through the precipitation of silica from aqueous solutions or accumulation of siliceous oozes on ocean floors, later undergoing diagenesis and compaction over millions of years.
Uses & applications
Used historically for stone tools and arrowheads due to its conchoidal fracture, and currently prized for ornamental carvings, cabochons, and gemstone collecting.
Geological facts
Jasper has been used by humans for over tens of thousands of years to create tools and decorative items. The reddish colors are typically caused by iron(III) inclusions.
Field identification & locations
Can be identified in the field by its high hardness (scratches glass), waxy or dull luster, and smooth conchoidal fracture surfaces. Commonly found in riverbeds, glacial tills, and marine sedimentary formations worldwide.
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