sedimentary

Banded jasper / iron-rich chert (probable)

Microcrystalline quartz (SiO₂) with iron oxides/hydroxides and clay minerals

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque rusty red, orange, gray, and black bands with a dull to waxy luster. It is very fine-grained, lacks visible cleavage, and commonly shows conchoidal fracture; exact identification is limited by the photograph.

Identified September 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed as chemically precipitated silica-rich sediment later stained and banded by iron minerals, followed by lithification and silicification. Such deposits range from Precambrian iron-formations to younger volcanic- or sediment-associated cherts.

Uses & applications

Used as ornamental stone, lapidary material, cabochons, carvings, and occasionally aggregate; attractive polished pieces have modest collector value.

Geological facts

The dark bands may contain hematite or magnetite, while red and orange zones commonly reflect hematite and goethite. A polished surface would reveal whether the banding is true jasper/chert or a strongly altered volcanic rock.

Field identification & locations

Common in iron-rich sedimentary terrains, including parts of Australia, India, Brazil, South Africa, and the United States. A steel file should barely scratch it; streak is typically reddish-brown, and dilute acid produces no fizz unless carbonate is present.