d031b852_ध_रस_यन___क__स_च____व_क_प_ड_य___Source_and_description
[Chemical name] manganese dioxide [Chemical formula] MnO2 [Common or alternative name] ----- [Source and description] 
Available as the black powder in unused alkaline or carbon-zinc batteries. By extensively washing this powder in distilled water you can remove the embedded Zinc Chloride solution.
सरलता से उपलब्ध रसायनों की सूची - विकिपीडिया