Warwickite
Warwickite is an iron magnesium titanium borate mineral with formula: (MgFe)3Ti(O, BO3)2 or Mg(Ti,Fe, Al)(BO3)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 of 3.36.