is an iron magnesium titanium borate mineral
with formula: (MgFe
)O. It occurs as brown to black prismatic orthorhombic
crystals which are vitreous and transparent. It has a Mohs hardness
of 3 to 4 and a specific gravity
It occurs metasomatized limestone skarns and in lamproite and carbonatite veinlets. It was first described in 1838 near Warwick, Orange County, New York. It has also been reported from Bancroft, Ontario; in Murcia Province, Spain; in Siberia and near
Pyongyang, North Korea.