Zeeman spectroscopy is used to demonstrate that phenomenological crystal-field parameters determined for the two C 1 point-group sites in Er 3+ :Y 2 SiO 5 may be transferred to other ions. The two crystallographic sixand seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations. 1 arXiv:1811.00158v1 [cond-mat.mtrl-sci]

Zeeman spectroscopy is used to demonstrate that phenomenological crystal-field parameters determined for the two C _1 point-group symmetry sites in Er^3+:Y_2SiO_5 may be transferred to other ions. The two crystallographic six-and seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations.