sedimentary

Chert (Quartzite Pebble)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Tan, cream, white with iron staining; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Tan, cream, white with iron staining
Luster: Dull to waxy

Identified June 23, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Tan, cream, white with iron staining; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed primarily as a sedimentary rock composed of microscopic quartz crystals. This specific specimen is a water-worn river or beach pebble, smoothed by mechanical erosion over thousands of years within high-energy water environments.

Uses & applications

Historically used for stone tools (arrowheads). Modern uses include construction aggregate, landscaping, and lapidary tumbling for hobbyists.

Geological facts

Chert is extremely durable and chemically stable, allowing it to survive long-distance transport in rivers. It often contains microfossils of radiolaria or diatoms.

Field identification & locations

Identify in the field by its hardness (it will scratch glass) and its smooth, rounded 'potato-like' appearance when found as a pebble. Commonly found in riverbeds and on beaches worldwide.