CaS has been studied as a component in a process that would recycle gypsum, a product of flue-gas desulfurization.
In terms of its atomic structure, CaS crystallizes in the same motif as sodium chloride indicating that the bonding in this material is highly ionic.
[2] Milk of lime, Ca(OH)2, reacts with elemental sulfur to give a "lime-sulfur", which has been used as an insecticide.
Calcium sulfide is phosphorescent, and will glow a blood red for up to an hour after a light source is removed.
It is a rare component of some meteorites and has scientific importance in solar nebula research.