Wikipedia
Breunnerite
Breunnerite is a variety of magnesite, with a magnesium / iron ratio of 90/10 to 70/30.
It has been described by Wilhelm Karl Ritter von Haidinger in samples of Pfitsch pass, Zamser Grund and Großer Mt Greiner, Zemmgrund two cites of the Ziller Valley, Tyrol, Austria.