Breunnerite

Breunnerite, also known as brown spar is a variety of magnesite, with a magnesium/iron ratio of 90/10 to 70/30.

Name and history

It has been described by Wilhelm Karl Ritter von Haidinger in samples of Pfitsch pass, Zamsergrund and, two cities of the Ziller Valley, Tyrol, Austria.
Haidinger named the new variety of the magnesite in honor of Count , a famous collector of minerals and fossils, as well as a high-ranking government official of Austria-Hungary.
In 19th-century mineralogy, as well as in mining and among geologists, breunnerite and its close analogues from the isomorphic series magnesite → siderite were more often known under the capacious morphological name ″brown spar″.

Application

Breunerite is widely used in firing during the formation of raw materials for the subsequent production of refractories. When magnesium carbonate, which is part of breunerite, is brought to a temperature of about 600°C, it enters the firing process as a mineralizer, first decomposing and then reacting and forming two main compounds that act as raw materials: 2CaFe₂O₃ и MgOFe₂O₃. Breunerite produces a less pure product than a mixture of magnesia and iron oxide, but is more economical to produce.