sedimentary

Chert (likely flint)

Microcrystalline quartz, SiO₂ (chalcedony/quartz aggregate)

AI-generated identification · may be incorrect

Typically Mohs 6.5–7; cream to honey-yellow with translucent edges, waxy to dull luster, very fine-grained and lacking visible crystals or cleavage. The sharp, conchoidal-looking fracture and mottled surface are consistent with chert, though the image alone cannot confirm the exact variety.

Identified August 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms mainly by silica replacement or accumulation of microscopic marine organisms in sedimentary beds, commonly during the Paleozoic–Mesozoic eras. It occurs as nodules, lenses, or layers in limestone and chalk.

Uses & applications

Used historically for stone tools and fire-starting because it fractures into sharp edges; today it is mainly a collector specimen, decorative stone, or occasional aggregate.

Geological facts

Flint is a dark-colored chert variety, while pale honey or cream material is often simply called chert or chalcedonic chert.

Field identification & locations

Identify by its hardness, glassy/waxy appearance, lack of cleavage, and sharp conchoidal fracture; common worldwide in limestone regions. A scratch test against steel or glass can help, but avoid damaging valuable pieces.