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Rock · Silicate

Chert

SiO₂ (cryptocrystalline)

Sedimentary cryptocrystalline silica — flint is the dark nodule form.

Hardness7
Crystal systemTrigonal
ClassSilicate
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Chert specimen

Chert nodule ("flint") from the Upper Cretaceous of England. Chert is a microcrystalline to cryptocrystalline, quartzose sedimentary rock. It can be any color, — Photo: James St. John · CC BY 2.0

Chert

Also known as: Flint, Jasper (red).

A hard, fine-grained sedimentary rock of microcrystalline quartz — usually of biological origin, and the material of flint tools.

Intro adapted from Wikipedia (CC BY-SA).

Chert is a rock-forming material, with the chemical formula SiO₂ (cryptocrystalline).

It crystallizes in the trigonal crystal system.

Key properties: Mohs hardness 7; typically white or gray or brown or red.

Collections: Everyday Minerals.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet. Browse more C minerals or help write this entry.