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Category Nesosilicates
(repeating unit)
Strunz classification 9.AD.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/n
Unit cell a = 5.5, b = 6.74
c = 9.29 [Å]; β = 94.59°; Z = 4
Color White to gray
Crystal habit Flattened anhedral grains; massive
Twinning Common, polysynthetic parallel to {100}
Cleavage Good on {100}, imperfect on {010}
Mohs scale hardness 6
Luster Vitreous
Streak White
Diaphaneity Transparent to translucent
Specific gravity 3.28–3.33
Optical properties Biaxial (+)
Refractive index nα = 1.707 nβ = 1.715 nγ = 1.730
Birefringence δ = 0.023
2V angle 74° calculated
Dispersion r > v
References [1]

Larnite is a calcium silicate mineral with 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.[1] 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.[1]

Dicalcium silicate is chemically, β–Ca2SiO4, sometimes represented by the formula 2CaO·SiO2. When used in the cement industry, the mineral is usually referred to as belite.


  • Deer, William Alexander; Howie, R. A; Zussman, J (1986). "Larnite". Disilicates and ring silicates. pp. 248–249. ISBN 978-1-897799-89-5.