mineral

Limonite-stained ironstone, possibly goethite

Goethite/limonite (FeO(OH) and hydrated iron oxides), identification tentative

AI-generated identification · may be incorrect

Dark brown to black, earthy-to-submetallic luster with rusty yellow-brown coatings; hardness about 4–5.5 Mohs, opaque, irregular fracture, and no obvious cleavage. The specimen appears dense and iron-rich, though a photo cannot confirm composition.

Identified September 16, 2026More mineral →

Explore Limonite-stained ironstone, possibly goethite in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Forms by oxidation and weathering of iron-bearing minerals, commonly as a replacement or cavity coating in soils, veins, and altered rocks; formation may range from recent weathering to ancient deposits.

Uses & applications

Used as an iron ore and historically as a brown-yellow pigment; attractive pieces are collected but are generally not gem material.

Geological facts

Goethite commonly develops botryoidal, fibrous, or stalactitic forms, while “limonite” is a field term for poorly crystalline hydrated iron oxides rather than a single mineral.

Field identification & locations

Look for a rusty streak, high density, opaque brown-black color, and association with weathered iron minerals; a streak test and hardness test help distinguish it from hematite, magnetite, and sulfides. Common worldwide, especially in laterites, gossans, and oxidized ore zones.