sedimentary

Chert or flint fragment

Microcrystalline quartz (SiO₂), possibly iron-stained chert

AI-generated identification · may be incorrect

Hardness about 7 Mohs; typically brown, gray, or reddish-brown with a waxy to dull luster and conchoidal fracture. It is cryptocrystalline, lacks visible cleavage, and has specific gravity near 2.6.

Identified August 14, 2026More sedimentary →

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Physical properties

Hardness about 7 Mohs; typically brown, gray, or reddish-brown with a waxy to dull luster and conchoidal fracture. It is cryptocrystalline, lacks visible cleavage, and has specific gravity near 2.6.

Formation & geological history

Chert forms when silica-rich biogenic material or groundwater precipitates and replaces sediment, commonly in limestone or marine beds. Its age cannot be determined from the image and may range from Precambrian to recent.

Uses & applications

Used historically for tools, arrowheads, fire-starting, and aggregate; attractive polished pieces are collected but usually have modest value.

Geological facts

The translucent, sharp-edged fracture and brown iron-oxide staining are characteristic of chert or flint, though the image alone cannot distinguish the exact variety.

Field identification & locations

Common in limestone regions, river gravels, and glacial deposits worldwide; test with a steel file or glass—true chert can scratch glass and does not fizz in dilute hydrochloric acid.