sedimentary

Chert (Light Variety)

Sedimentary cryptocrystalline quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Creamy white to light tan; Luster: Dull to waxy; Texture: Fine-grained with conchoidal (shell-like) fracture edges; Cleavage: None.

Hardness: 7 (Mohs scale)
Color: Creamy white to light tan
Luster: Dull to waxy

Identified July 1, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale); Color: Creamy white to light tan; Luster: Dull to waxy; Texture: Fine-grained with conchoidal (shell-like) fracture edges; Cleavage: None.

Formation & geological history

Formed from the accumulation of silica-rich organic remains (like radiolaria or diatoms) or chemical precipitation in marine or freshwater environments during various geological eras from Precambrian to Cenozoic.

Uses & applications

Historically used for stone tools (knapping for scrapers or arrowheads) due to its sharp fracture edges. Today it is used as road aggregate or as a lapidary material if it contains colorful patterns.

Geological facts

Chert is so hard it can scratch steel and was used for centuries as a flint to start fires when struck against steel. This specific light-colored variety is often found in limestone or dolostone layers.

Field identification & locations

Identify by its extreme hardness and the smooth, curved surfaces where it has broken. Commonly found in outcroppings of sedimentary rock or as river-worn pebbles. For collectors, look for sharp edges and density.