MnS adopts the cubic NaCl (rocksalt) structure under normal conditions (alpha-MnS). However, MnS crystals adopting the zinc blende structure (beta-MnS) can also be grown under appropriate conditions.

The Rocksalt (NaCl) Structure	The Zinc Blende (ZnS) Stucture

Mn²⁺ has 5 d-electrons and is observed in a high spin configuration (i.e. t_2g³, e_g²) in both alpha- and beta-MnS. This leads to a number of possible `spin structures' and these are shown opposite.

Both alpha-(rocksalt) and beta-(zinc blende) MnS have a face centred cubic array of cations so the magnetic structures shown apply to both allotropes.

Alpha-MnS adopts the antiferromagnetic AF2 structure.

Beta-MnS is observed in the AF3 configuration.