Signatures of Ni2+ and Fe3+ in the optical spectra of limonitic ore from new caledonia: Application to the determination of the nickel content

A spectrometric study has been made over the range from 400 to 1500 nm on powdered specimens of saprolitic, nickel-bearing ore minerals from New Caledonia; analysis of the absorption spectra enables a distinction to be made between features due to Fe³⁺ and those due to Ni²⁺. Measurement of diffuse reflectance in the visible range makes it possible to estimate (to about 2% relative) the amount of nickel in the saprolites. The simplicity of the method and the fact that it is applied to powdered material enable these spectral characteristics of nickel to be used in prospecting for nickel or in the estimation of resources, eventually by remote-sensing.