sedimentary

Likely polished jasper or brecciated chert

Microcrystalline quartz (SiO₂), possibly with iron-oxide and carbonate inclusions

AI-generated identification · may be incorrect

Opaque tan, brown, cream, and gray material with mottled/brecciated pattern and a polished or naturally smooth surface; quartz hardness is about 6.5–7 Mohs, with vitreous to waxy luster and no visible cleavage. Exact identification is limited by the photograph and lighting.

Identified August 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, often incorporating iron oxides and angular fragments; ages vary widely from Precambrian to recent. Commonly develops in volcanic, hydrothermal, or sedimentary environments.

Uses & applications

Used for cabochons, carvings, beads, lapidary objects, and ornamental pieces; some varieties are used as decorative stone. This small specimen has modest collector value.

Geological facts

Jasper is an opaque variety of chalcedony, while chert is its closely related silica-rich rock; the boundary between them is often informal. Iron oxides produce the yellow-brown coloration.

Field identification & locations

Look for a waxy polish, opaque fine-grained texture, curved conchoidal fracture, and inability to scratch it with a steel knife; it should scratch ordinary glass. Common sources include Brazil, Madagascar, India, Mexico, and the western United States.