sedimentary

Tumbled chert or flint pebble

Microcrystalline quartz (SiO₂), likely chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; smooth, tan to honey-brown surface with dull-to-waxy luster, very fine-grained texture, and no visible crystals or cleavage. The fracture line suggests conchoidal fracturing typical of silica-rich chert.

Identified August 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when microcrystalline quartz replaces or accumulates from silica-rich sediments, often in limestone or marine deposits; its exact age cannot be determined from the photograph. Natural abrasion or tumbling produced the rounded shape and polished surface.

Uses & applications

Used historically for tools, sparks, and arrowheads; today it is mainly a lapidary, landscaping, and inexpensive collecting material. Attractive examples may be sold as polished or tumbled stones.

Geological facts

Chert and flint are mineralogically similar; “flint” commonly refers to dark, dense chert, while this pale specimen is better called chert or jasper-like chert.

Field identification & locations

Identify it by its uniform cryptocrystalline texture, waxy appearance, lack of cleavage, and ability to scratch glass. Common in sedimentary terrains and gravel deposits worldwide; exact identification would benefit from a streak, hardness, and translucency test.