sedimentary

Reddish-brown jasper/chert with iron staining

Microcrystalline quartz (SiO₂), likely ferruginous jasper or chert

AI-generated identification · may be incorrect

Opaque reddish-brown to gray, earthy to dull luster, very fine-grained and massive; hardness about 6.5–7 Mohs, no visible cleavage, conchoidal-to-uneven fracture. The dark band may be manganese- or iron-rich material, with possible thin quartz veining.

Identified September 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, commonly in ancient marine, volcanic, or hydrothermal environments; iron and manganese oxides create the red, brown, and black colors. The specimen’s exact geological age cannot be determined from the photograph.

Uses & applications

Used for cabochons, beads, carvings, tumbling, ornamental stone, and small decorative objects; generally unsuitable for major construction because of its small specimen size.

Geological facts

Jasper is an opaque variety of chalcedony/microcrystalline quartz, while chert is the broader rock term; visual separation is often informal without laboratory testing.

Field identification & locations

Commonly found in silica-rich sedimentary beds, volcanic terrains, and river gravels worldwide. A glassy conchoidal fracture, resistance to scratching by a steel blade, and lack of reaction to dilute acid support identification as jasper/chert rather than limestone.