sedimentary

Tumbled brown jasper (probable iron-stained chert)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide impurities

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown, tan, and reddish mottling; dull to waxy luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The smooth rounded shape indicates natural water wear or tumbling.

Identified September 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when silica replaced or cemented fine sediment, with iron oxides producing the brown coloration; typically Paleozoic to younger depending on its source formation. Common sources include river gravels, volcanic-sedimentary environments, and weathered chert beds.

Uses & applications

Used as a lapidary material for cabochons, beads, carvings, polished stones, and decorative aggregate; not generally used as a major construction stone.

Geological facts

Jasper is an opaque variety of chalcedony or chert, unlike translucent agate. Small pits and surface cavities may reflect weathering, original porosity, or incomplete polishing.

Field identification & locations

Identify it by its opaque earthy color, very fine texture, waxy surface, and ability to scratch ordinary glass; it should not fizz in dilute hydrochloric acid. Exact locality and composition cannot be confirmed from the image alone.