sedimentary

Likely chert or jasper fragment

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

AI-generated identification · may be incorrect

Opaque reddish-brown, dull to waxy luster, fine-grained with no visible crystals or cleavage; hardness about 6.5–7 Mohs and specific gravity near 2.6. The rough, conchoidally fractured appearance is consistent with silica-rich stone.

Identified September 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when microcrystalline quartz replaces or accumulates from silica-rich sediments; red jasper is iron-oxide-stained chert. Formation may range from Precambrian to recent sedimentary environments, but age cannot be determined from the image.

Uses & applications

Used for sharp-edged tools, stone flaking, ornamental objects, beads, and lapidary cabochons; attractive jasper may be polished for jewelry or decoration.

Geological facts

Iron oxides produce the red-to-brown coloration. Chert commonly breaks with curved, shell-like fracture surfaces rather than along cleavage planes.

Field identification & locations

Identify it by its very fine texture, lack of visible grains, glassy/waxy fracture, and inability to scratch it with a steel knife; it should scratch ordinary glass. Common worldwide in sedimentary formations and gravel deposits.