sedimentary
White chert (flint)
Microcrystalline quartz, SiO₂
AI-generated identification · may be incorrectWhite to pale gray, opaque, with a waxy to dull luster and irregular, sharp conchoidal fractures. Hardness is about 7 Mohs; crystals are microscopic, with no cleavage.
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Physical properties
White to pale gray, opaque, with a waxy to dull luster and irregular, sharp conchoidal fractures. Hardness is about 7 Mohs; crystals are microscopic, with no cleavage.
Formation & geological history
Forms when silica accumulates and replaces material in sedimentary settings, often in limestone or chalk. Its age cannot be determined from the image and depends on the source deposit.
Uses & applications
Chert has been used for stone tools and, historically, fire-starting; attractive pieces are collected or used decoratively.
Geological facts
The flaked surfaces and curved fracture marks are characteristic of chert, though appearance alone cannot confirm the identification.
Field identification & locations
Look for hardness, waxy luster, and conchoidal fracture; chert occurs worldwide in sedimentary formations. A hand specimen like this commonly sells for about $1–$10.
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