Limonite (Goethite) pseudomorph after Pyrite/Marcasite

Limonite (Goethite) pseudomorph after Pyrite/Marcasite

Sahara, North Africa.

A single piece. About 38mm x 28mm x 30mm in size. Weight approx. 68g.

In this spectacular piece, limonite or goethite (also an iron hydroxy mineral) has almost completely replaced the original crystal structure of pyrite or marcasite. This exceptionally beautiful, rare specimen is unevenly round in shape. The color is a beautiful reddish dark brown, with the dull golden glow of pyrite or marcasite.

Limonite is a general name for hydrous iron oxide precipitates. They are also called lake and marsh ores, depending on the place of precipitation. Before the large-scale start of mining, limonite was the most important raw material for iron production in Finland. Folk names for limonite are hölmä, malavi, rautamaa, malvi and rauamult. As an actual mineral species, they mostly contain goethite when the substance is crystalline. Pseudomorphosis is a geological phenomenon in which the original mineral of a mineral grain changes to another, but its original shape remains.