Rock Identifier
Earthy iron-oxide-rich mineral coating (probable laterite/limonite) (Hydrated iron oxides and oxyhydroxides, chiefly goethite (FeO(OH)) and limonite (variable FeO(OH)·nH₂O), mixed with clay/sand) — mineral
mineral

Earthy iron-oxide-rich mineral coating (probable laterite/limonite)

Hydrated iron oxides and oxyhydroxides, chiefly goethite (FeO(OH)) and limonite (variable FeO(OH)·nH₂O), mixed with clay/sand

AI-generated identification · may be incorrect

Rust-red to brown, dull earthy luster, fine-grained and porous; hardness roughly 4–5.5 for goethite, with no visible crystals or cleavage. The photographed material appears spread as a thin, possibly wet or coated aggregate rather than a solid hand specimen, so identification is provisional.

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Physical properties

Rust-red to brown, dull earthy luster, fine-grained and porous; hardness roughly 4–5.5 for goethite, with no visible crystals or cleavage. The photographed material appears spread as a thin, possibly wet or coated aggregate rather than a solid hand specimen, so identification is provisional.

Formation & geological history

Forms by intense chemical weathering and oxidation of iron-bearing rocks, producing lateritic soil, ferruginous crusts, or gossan-like coatings. Such weathering is generally young compared with the host rock and is plausible in Yemen’s arid-to-seasonally weathered highlands near 15.4°N, 44.2°E.

Uses & applications

Used as an iron ore when sufficiently concentrated, natural pigment (ochre), and sometimes as a low-grade abrasive or collector specimen; generally little jewelry value.

Geological facts

Iron oxides commonly stain rocks and soil vivid red, orange, or brown. A red streak and attraction to a strong magnet, if present from associated magnetite, can help distinguish it from ordinary clay.

Field identification & locations

Likely regional lateritic/ferruginous sediment or weathering residue rather than a discrete crystal. Test streak on unglazed ceramic, hardness, density, and acid reaction; avoid relying on color alone. Estimated value: $1–$10 for common material, up to $20–$50 for attractive botryoidal or crystalline goethite.