Family Life What is the color of MnO2? What is the color of MnO2? black Is manganese dioxide Black in colour? Manganese dioxide (MnO2) is an inorganic compound. It is a black to brown-colored material that occurs naturally as the mineral pyrolusite (see Figure 1).Mar 3, 2013 Related Posts:How is manganese dioxide removed from water?Are Glass Kettles Safe?Look good and be safe with these glass electric kettleIs American Manganese a good investment?How to Shrink Wrap Bath Bombs with The PackageMaster Shrink System.