sedimentary

Iron-rich sandstone or weathered laterite

Ferruginous sandstone, composed mainly of quartz with iron-oxide cement (Fe₂O₃/FeOOH)

AI-generated identification · may be incorrect

Fine-grained, reddish-brown to dark brown, earthy and dull-matte with granular texture; likely Mohs hardness 5–7 for quartz grains, but friable overall. No obvious cleavage; low to moderate density and irregular fracture.

Identified August 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably formed from compacted sand cemented by iron oxides, or developed as a weathering crust in a tropical/subtropical soil profile. Its precise geological age cannot be determined from the image and may range from recent weathering to ancient sedimentary rock.

Uses & applications

Used locally as building stone, aggregate, road material, or pigment source; attractive pieces may be kept as natural specimens, though it is generally not a jewelry material.

Geological facts

The brown color results from hematite, goethite, or limonite coatings between quartz grains. Iron-rich rocks commonly develop a hard outer rind and can leave a rusty streak or stain.

Field identification & locations

Look for visible sand grains, earthy iron staining, moderate heft, and a lack of vesicles or glassy surfaces; a streak test, dilute acid test, and hardness test would help distinguish it from volcanic rock or soil concretion. Common in weathered tropical terrains and sedimentary basins.