What is "larnite"

n. a polymorph of calcium silicate, Ca₂SiO₄, found in limestone or chalk in contact with semimolten basalts

Larnite is a calcium silicate mineral with formula: CaSiO.

It was first described from an occurrence at Scawt Hill, Larne, Northern Ireland in 1929 by Cecil Edgar Tilley and named for the location. 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.

Dicalcium silicate is chemically, β–CaSiO, sometimes represented by the formula 2CaO·SiO. When used in the cement industry, the mineral is usually referred to as belite.