sedimentary

Chert (specifically Flint or Jasper variant)

Microcrystalline quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Brown, tan, and dark gray; Luster: Waxy to vitreous; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Brown, tan, and dark gray
Luster: Waxy to vitreous

Identified July 1, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brown, tan, and dark gray; Luster: Waxy to vitreous; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed through the accumulation of silica-rich fluids in sedimentary environments, often replacing carbonate material or precipitating from groundwater. Common in limestone and chalk beds.

Uses & applications

Historically used for stone tools and weapons due to its sharp edges; used today as decorative stones, in construction aggregate, and occasionally in lapidary work.

Geological facts

Chert (or flint) was one of the most important minerals for early humans, used to create fire and sharp projectiles. It can contain microfossils of diatoms or radiolarians.

Field identification & locations

Identify by its characteristic conchoidal (shell-like) fracture and high hardness (it will scratch glass). Often found in riverbeds or as nodules within limestone outcrops.