sedimentary

Banded, weathered chert or silicified pebble

Microcrystalline quartz (SiO₂), likely chert/jasper; exact identification requires testing

AI-generated identification · may be incorrect

Typically hardness ~6.5–7 Mohs, opaque, gray-brown to tan, with a dull to waxy luster and irregular mottled or banded texture. It lacks visible cleavage and appears naturally water-rounded and weathered.

Identified August 27, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater replaced or cemented sediment, commonly during diagenesis; its exact geological age cannot be determined visually. The rounded shape indicates later transport by water or wave action.

Uses & applications

Common chert is used as aggregate, road material, and historically for sharp tools; attractive patterned pieces are collected or polished for cabochons and decorative objects.

Geological facts

Chert may preserve fossils or sedimentary textures, while jasper is an iron-rich opaque variety with stronger red, yellow, or brown coloration. A steel file should not easily scratch it, and it may produce a sharp conchoidal fracture.

Field identification & locations

Common in sedimentary terrains, gravel bars, beaches, and glacial deposits worldwide. Confirm with a streak, hardness, conchoidal-fracture, and acid test; avoid destructive testing on valuable specimens.