sedimentary

Weathered sandstone or iron-rich quartzite fragment

Quartz-dominated siliciclastic rock; likely ferruginous sandstone (SiO₂-rich)

AI-generated identification · may be incorrect

Tan, fine- to medium-grained, dull and strongly weathered, with rusty-brown staining; apparent hardness about 6–7 if quartz-rich, but exact cleavage and density cannot be judged from the image. The broken edge appears granular rather than crystalline.

Identified September 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely lithified sand cemented by silica or iron oxides, later fractured and weathered near the surface; its precise geological age cannot be determined photographically. Sandstones and quartzites are plausible around southeastern Brazil, including the Rio de Janeiro region.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally as a decorative stone; this weathered fragment has little commercial or collector value.

Geological facts

The yellow-brown color commonly comes from limonite/goethite coatings or iron-oxide cement, not necessarily from a separate yellow mineral.

Field identification & locations

Look for visible sand grains, quartz-rich sparkle, and no strong cleavage; a steel nail may scratch softer sandstone but usually will not scratch quartzite. A streak, acid test, and close inspection of grain boundaries would distinguish sandstone from quartzite and weathered volcanic rock.