MANGANESE OXIDE Molecular formular  MnO Molecular weight 70.94 CAS NO. 1344-43-0 Property  grass green or gray green color cube crystal powder of octahedron crystal. Relative density: 5.43-5.46. Melting point: 16500C. If temperature is reaching 34000C, it'll separate and sublimation. It's not soluble with water, it's soluble with acid and ammonium chloride. MnO 60% Min Mn 46% Min Pb 0.010% Max Cd 0.010% Max As 0.010% Max