references:
  - Y.S. Touloukian et al.,
    TPRC Data Series Volume 1. Thermal conductivity - metallic elements and alloys,
    IFI/Plenum, 1970,
    fit to Tab. 61R (T_min=100K, T_max=400K)
  - https://www.engineeringtoolbox.com/specific-heat-metals-d_152.html

K_11: 7.414e+1
K_11,T: -6.465e-2
K_11,T^2: 2.066e-4

K_33: 5.147e+1
K_33,T: -4.506e-2
K_33,T^2: 1.435e-4

T_ref: 293.15

C_p: 210.0