What is "magnesium sulfide"

n. (context inorganic compound English) A white, crystalline powder (when pure), usually found in an impure, brown, non-crystalline form.

Magnesium sulfide is an inorganic compound with the formula MgS. It is a white crystalline material but often is encountered in an impure form that is brown and non-crystalline powder. It is generated industrially in the production of metallic iron.