ColorIron-black; gray with a brownish tint in reflected lightCrystal habitGranular to massive and lamellar exsolutions in hematite or magnetiteCrystal systemTrigonalTwinning{0001} simple, {1011} lamellarCleavageabsent; parting on {0001} and {1011}FractureConchoidal to subconchoidalTenacityBrittleMohs scale hardness5?6LusterMetallic to submetallicStreakBlackDiaphaneityOpaqueSpecific gravity4.70?4.79Optical propertiesUniaxial (?)BirefringenceStrong; O = pinkish brown, E = dark brown (bireflectance)Other characteristicsweakly magnetic