Manganese is a pinkinsh-gray, chemically active element. It is a hard metal and is very brittle. It is hard to melt, but easily oxidized. Manganese is reactive when pure, and as a powder it will burn in oxygen, it reacts with water (it rusts like iron) and dissolves in dilute acids.Applications. Manganese is essential to iron and steel production. At present steel making accounts 85% to 90% of the total demand, most of the total demand.anganese is reactive when pure, and as a powder it will burn in oxygen, it reacts with water (it rusts like iron) and dissolves in dilute acids. Applications. Manganese is essential to iron and steel production. At present steel making accounts 85% to 90% of the total demand, most of the total demand.