Larnite is a calcium silicate mineral with the formula Ca2SiO4.
It was first described from an occurrence at Scawt Hill, Larne, Northern Ireland in 1929 by Cecil Edgar Tilley and named for the location.
[2] At the type locality it occurs with wollastonite, spurrite, perovskite, merwinite, melilite and gehlenite.
It occurs in contact metamorphosed limestones and chalks adjacent to basaltic intrusives.
[2] Dicalcium silicate is chemically β–Ca2SiO4, sometimes represented by the idealized oxide formula 2CaO·SiO2 also noted C2S in the cement chemist notation (CCN).