Calcite

Material

Calcite (CaCO3) belongs to the most stable polymorph calcium carbonates. It defines the Mohs hardness scale with 3 as the hardness. That means that the material can be scratched with a copper coin. It dissolves in acids where ambient CO2 and water is enough to show slight dissolution. Transparent calcite is interesting because of its strong birefringence.

 

As a result, calcite is used for polarizers (e.g., as Glan-Foucault prism) and for waveplates (λ/n plates).

Properties
Optical properties
Transmission range in µm (minimum 50%)
0,21‐5,2
Refractive index @633nm
no= 1,656

ne= 1,485

Reflection losses in % at 1 surface
6,1 @633 nm
Reflection losses, % for two surfaces
11,7 @510 nm
dN/dT in 1/K
3·10-6 (∥ c-axis) @500 nm

13·10-6(⊥ c-Achse) @500 nm

Physical properties
Density in g/cm3
2,71
Melting point in °C
>700 (dissolved)
Specific heat capacity in J/(kg · K)
822
Thermal conductivity in W/(m · K)
5,526 (∥ c-axis)

4,646 (⊥ c-axis)

Thermal expansion in 1/K
25·10-6 (∥ c-axis)

-5,8·10-6 (⊥ a-axis)

Dielectric constant
8 (∥ c-axis)

8,5 (⊥ c-axis)

Solubility in water in g/100g
0,0014 @20°C
Mohs hardness
3
Knoop hardness in kg/mm²
135
Material type
Single crystal
Crystal structure
hexagonal
Lattice constant in Å
a= 4,989

c= 17,062

Elastic coefficient in GPa
C11 = 144

C12 = 53,9

C13 = 51,1

C14 = -20,5

C33 = 84

C44 = 33,5

Young's Modulus (E) in Gpa
72,35 (∥ c-axis)

88,19 (⊥ c-axis)

Shear Modulus (G) in GPa
32
Bulk Modulus (K) in GPa
129,6
Rupture Modulus in MPa
4,83
Poisson's ratio
0,31
Spectral properties
sample thickness: 2 mm
Optical properties
Transmission range @10% min. 0,14 - 15
Transmission range @50% min. 0,14 - 14
Brechungsindex @ 633nm 1,47326
(1,45@5µm)
Reflection losses in % at 1 surface 3,4 @ 4µm
Reflection losses, % for two surfaces 6,5 @ 5µm
dn/dT in 1/K -15,2 · 10-6
Physical properties
Density in g/cm³ 4,89
Melting point in °C 1368
Specific heat capacity in J/(kg · K) 410
Thermal conductivity in W/(m · K) 10,9
Thermal expansion in 1/K 18,4 · 10-6
Dielectric constant 7,33
Solubility in water in g/100g 0,16 @ 25°C
Mohs hardness 3
Knoop hardness in kg/mm² 82
Material type single crystalline, synthetic
Crystal type kubisch, CaF2 structure
Crystal structure cF12
Lattice constant in Å a = 6,2
Elastic coefficient in GPa C11 = 91
C12 = 41,2
C44 = 25,3
Young's Modulus (E) in Gpa 53,07
Shear Modulus (G) in GPa 25,4
Bulk Modulus (K) in GPa 57,8
Rupture Modulus in MPa 26,9
Apparent elastic limit in MPa 26,9
Poisson's ratio 0,31
Spectral properties