sedimentary
Chert / Quartzite
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness 7 on Mohs scale, yellowish-brown to tan color, waxy to vitreous luster, conchoidal fracture, trigonal crystal system microcrystalline, specific gravity 2.65
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Physical properties
Hardness 7 on Mohs scale, yellowish-brown to tan color, waxy to vitreous luster, conchoidal fracture, trigonal crystal system microcrystalline, specific gravity 2.65
Formation & geological history
Formed through the accumulation of microcrystalline silica in sedimentary environments or by low-grade metamorphism of quartz sandstone.
Uses & applications
Historically used for stone tools, flintknapping, and arrowheads. Modern uses include aggregate in construction, landscaping, and lapidary polishing.
Geological facts
Chert and chalcedony are composed of cryptocrystalline quartz, making them extremely hard and resistant to chemical weathering.
Field identification & locations
Identified by its hardness (scratches glass), smooth conchoidal fracture surfaces, and translucent to opaque appearance. Commonly found along riverbeds, glacial deposits, and sedimentary rock formations worldwide.
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