sedimentary

Reddish-brown chert or jasper fragment

Microcrystalline quartz (SiO₂), likely iron-oxide-stained chert/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque reddish-brown with a dull to waxy luster, very fine-grained texture, and conchoidal fracture. No visible cleavage; specific gravity approximately 2.6.

Identified August 23, 2026More sedimentary →

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Physical properties

Hardness about 6.5–7 Mohs; opaque reddish-brown with a dull to waxy luster, very fine-grained texture, and conchoidal fracture. No visible cleavage; specific gravity approximately 2.6.

Formation & geological history

Forms when silica-rich groundwater replaces or cements sediment, commonly in limestone, volcanic, or marine environments; iron oxides produce the red-brown color. Its precise geological age cannot be determined from the image.

Uses & applications

Used as aggregate, road material, decorative stone, and historically for sharp tools; attractive pieces may be cut or polished as ornamental jasper.

Geological facts

Chert and jasper are varieties of cryptocrystalline quartz composed of microscopic quartz crystals or chalcedony. The specimen appears naturally weathered and partially rounded.

Field identification & locations

Common in stream gravels, beaches, deserts, and sedimentary outcrops; identify by its hardness, opaque color, waxy surface, and sharp conchoidal edges. A steel file should barely scratch it, while it can scratch glass.