sedimentary

Chert / Pink Flint

Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Pink, tan, and creamy white; Luster: Waxy to vitreous; Crystal Structure: Hexagonal (microscopic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Pink, tan, and creamy white
Luster: Waxy to vitreous

Identified March 30, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Pink, tan, and creamy white; Luster: Waxy to vitreous; Crystal Structure: Hexagonal (microscopic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms) or chemical precipitation in sedimentary basins. The pink hue often comes from trace iron oxide inclusions. Found in rock layers ranging from Precambrian to recent.

Uses & applications

Historically used for stone tools and weapons due to sharp edges; currently used for lapidary work, jewelry (cabochons), road surfacing, and as a component in ceramics and glass.

Geological facts

Chert was one of the first materials traded globally by early humans. This specific specimen shows conchoidal (shell-like) fracturing, a key trait that allows it to be knapped into arrowheads.

Field identification & locations

Identify in the field by its hardness (scratches glass), waxy feel, and sharp, curved fracture patterns. Commonly found in limestone beds or as nodules in riverbeds across the United States, especially in the Midwest and South.