Larnite
Larnite is a calcium silicate mineral with formula: Ca2SiO4. It is the calcium member of the olivine group of minerals.
| 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] |
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.
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