What is the color of manganese hydroxide? What changes the color of manganese hydroxide when it is oxidized in air?

Image: Manganese hydroxide (2 +) structural formula

Manganese hydroxide is used as a ceramic pigment, in the manufacture of other manganese compounds, as a paint drying agent, and in the treatment of wastewater containing organic acids in zinc electrolysis workshops.

Manganese hydroxide Mn (OH) 2, showing white crystals. It is very easy to react with oxygen in the air, and exposure to compounds that are quickly oxidized to brown in the air. Even trace amounts of oxygen dissolved in water can oxidize manganese hydroxide to form brown partial manganese hydroxide precipitation:: 2Mn (OH) 2 + O2 === 2MnO (OH) 2, so pure white manganese hydroxide is rare, usually with brown crystals.