The ESR spectrum of natural wollastonite has a strong angular dependence that we interpret as originating from Mn²⁺ions distributed among the 6-coordinated Ca sites (Cal, Ca2) and the 7-coordinated Ca site (Ca3). A computer fit to the spectrum shows superposition of spectra from Mn²⁺ ions in two magnetically nonequivalent kinds of sites with the Hamiltonian parameters g₁ = g₂= 2.002, A₁ = A₂ = 85 cm^-1 D, = D₂ = -357 cm^-1 and E₁ = E₂ = 90 cm^-1; and g₃ = 1.998, A₃ = 87 cm^-1,D₃ = -231 cm^-1, and E₃ = 19 cm^-1 with subscripts referring to the sites Cal, Ca2 and Ca3, respectively. A crystal-field calculation gives zero-field splitting ratios of and for the two signals, compared with the experimentally measured ratios and We interpret these signals as arising from Mn²⁺ on the 6-coordinated Ca sites (Cal, Ca2) and the 7-coordinated Ca site (Ca3).