sedimentary

Chert (Flint)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 Mohs; Color: Tan, brown, and grey; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 Mohs
Color: Tan, brown, and grey
Luster: Waxy to vitreous

Identified June 17, 2026More sedimentary →

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Physical properties

Hardness: 7 Mohs; Color: Tan, brown, and grey; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in marine environments via the accumulation of siliceous remains from organisms like diatoms and radiolarians, or through chemical precipitation in limestone/chalk beds. Dates from Precambrian to recent.

Uses & applications

Historically used for stone tools (arrowheads, knives) and striking fire; currently used as a decorative stone, in jewelry (lapidary), and as a surfacing material for roads.

Geological facts

Flint is a variety of chert that occurs in chalk or marly limestone. Because of its conchoidal fracture, it can be knapped into extremely sharp edges, some thinner than a steel scalpel.