Limonite

Limonite together with hematite are mined as ore for the production of iron. Limonite heavy and yellowish-brown. It is not a true mineral, however, but a mixture of similar hydrated iron oxide minerals, mostly Goethite. Limonite forms mostly in or near oxidized iron and other metal ore deposits and as sedimentary beds. Limonite has been known to pseudomorph other minerals such as pyrite, meaning it replaces a crystal of pyrite with limonite but keeps the shape of the pyrite crystal.

Hardness is 4 - 5.5, specific gravity is 2.9 to 4.3.

See also: List of minerals