An X‐Ray Diffraction Study of Manganese Dioxide

An x‐ray diffraction study has been made of the various types of manganese dioxide with particular emphasis on those prepared chemically. A review of the literature suggests that several types have received different names by different investigators. A diffraction pattern of ramsdellite, uncontaminated by the lines of pyrolusite, is reported. Three modifications of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="ML1" overflow="scroll"> <mml:mi>γ</mml:mi> <mml:mo>‐</mml:mo> <mml:msub> <mml:mi mathvariant="normal">MnO</mml:mi> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> are described and their relation to ramsdellite and pyrolusite is discussed. The manner in which lead is combined in a commercial manganese dioxide by‐product, and the part played by potassium in determining the course of various transformations, are also discussed.