Larnite
Appearance
Larnite | |
---|---|
General | |
Category | Nesosilicates |
Formula (repeating unit) | Ca2SiO4 |
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 |
Identification | |
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.
References
- Deer, William Alexander; Howie, R. A; Zussman, J (1986). "Larnite". Disilicates and ring silicates. pp. 248–249. ISBN 978-1-897799-89-5.