mineral

Limonite/goethite-rich ironstone

Hydrated iron oxides, chiefly goethite (α-FeO(OH)) and limonite (FeO(OH)·nH₂O)

AI-generated identification · may be incorrect

Brown to rusty-black, earthy to submetallic luster, irregular massive texture, and no visible cleavage; hardness about 4–5.5 Mohs, with moderate-to-high specific gravity (~3–4.3).

Identified August 13, 2026More mineral →

Explore Limonite/goethite-rich ironstone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Brown to rusty-black, earthy to submetallic luster, irregular massive texture, and no visible cleavage; hardness about 4–5.5 Mohs, with moderate-to-high specific gravity (~3–4.3).

Formation & geological history

Forms through oxidation and weathering of iron-bearing minerals, commonly as a soil or gossan crust; typically geologically young relative to its parent rock, though iron deposits may be ancient.

Uses & applications

Used as iron ore where sufficiently concentrated and historically as ochre pigment; attractive botryoidal or pseudomorphic specimens may be collected, but it is not normally a gemstone.

Geological facts

The specimen’s rusty brown coloration and dense, uneven surface are characteristic of hydrated iron oxides. A reddish-brown streak and yellow-brown powder are useful diagnostic clues.

Field identification & locations

Common in weathered outcrops, mine dumps, caves, and lateritic soils worldwide. Confirm with a streak test on unglazed porcelain; magnetism may indicate associated magnetite, while exact identification requires testing or analysis.