sedimentary

Weathered iron-rich chert or jasper

Microcrystalline quartz (SiO₂), variably stained by iron oxides/hydroxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; dark gray to black with orange-brown hematite/goethite patches, dull to waxy luster, and no obvious cleavage. The irregular conchoidal-looking fracture and very fine grain are consistent with chert/jasper.

Identified September 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when silica-rich material precipitated or replaced sediment, later acquiring iron staining during weathering; chert deposits range from Precambrian to recent geologic ages. Exact age and locality cannot be determined from the photograph.

Uses & applications

Common pieces are used as lapidary rough, cabochons, tumbled stones, and decorative objects; chert was historically important for sharp-edged tools and fire-starting. It has little commercial value unless exceptionally patterned or polished.

Geological facts

The orange coloration commonly reflects hematite or limonite/goethite rather than a separate orange mineral. Chert is chemically similar to flint, differing mainly in color, texture, and geological setting.

Field identification & locations

Look for a very fine-grained, hard surface that scratches glass and breaks with curved, sharp edges; a streak test and close inspection can distinguish it from slag or weathered metal. Similar material occurs worldwide, especially in limestone and ancient sedimentary formations.