sedimentary

Weathered sandstone or iron-stained sedimentary pebble

Quartz-rich sandstone; exact identification requires a fresh surface and tests

AI-generated identification · may be incorrect

Tan-brown, dull to earthy luster, visibly granular and porous with rounded weathering; predominantly quartz with possible feldspar, clay, and iron oxides. Likely Mohs hardness about 5–7 for grains, but weakly cemented overall; no obvious cleavage or crystal structure.

Identified August 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand was deposited, compacted, and cemented in a sedimentary basin, probably millions to hundreds of millions of years ago; brown coloration commonly comes from oxidized iron minerals. The rounded triangular shape reflects transport and weathering.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally decorative material; this small specimen has little commercial value unless locality or texture is unusual.

Geological facts

The apparent speckled surface may be weathered quartz grains or iron-rich cement rather than a separate mineral. A streak, acid, and magnification test would help distinguish sandstone from weathered volcanic rock.

Field identification & locations

Likely found in stream gravels, eroded outcrops, deserts, and construction fill; inspect a broken edge for sand grains and try scratching glass with a clean quartz-rich surface. No visible fossils or diagnostic structures are present.