sedimentary

Likely brown chert or jasper fragment

Microcrystalline quartz (SiO₂), possibly iron-stained chalcedony

AI-generated identification · may be incorrect

Opaque dark brown, irregularly triangular fragment with dull-to-waxy luster and no visible crystals; quartz hardness about 7 Mohs, conchoidal fracture, and specific gravity near 2.6. Exact identification is limited by the small, reflective image.

Identified September 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica-rich fluids replace or cement sediment, commonly from marine microscopic organisms; jasper is an iron-rich opaque variety. Formation ages range from Precambrian to recent, depending on the deposit.

Uses & applications

Used for prehistoric tools, lapidary carvings, cabochons, beads, and decorative stone; ordinary fragments have little commercial use.

Geological facts

A sharp edge and glass-like conchoidal fracture favor chert; red, yellow, or brown coloration commonly comes from iron oxides. It may also be a tumbled or polished piece.

Field identification & locations

Common in limestone and sedimentary terrains, river gravels, and glacial deposits worldwide. Test for hardness against ordinary glass and inspect for a waxy surface and shell-like fracture; acid reaction should be absent.