Introduction: The Ni-rich mineral phases forming the " garnierite " in the lateritic ore of the New Caledo-nian occurences are composed mainly in most cases by talc-like minerals, identified as kerolite. The Ni-Mg kerolite is a solid solution from Mg-kerolite to Ni-kero-lite (pimelite) with a structure close to the one of talc. The interlayer distance is of ~9.5 Å but with an excess of Mg in octahedral site, a relative deficit of Si in tetra-hedral site and a water content greater than the one in talc [1-4]. These minerals generally occur with a collo-morph texture, marked by a chemical zoning with growing bands characterized by alternative Ni/Mg ratio. However, the structure of these minerals is still not elucidated. Indeed, they form generally poor crystallized mixtures, in particular with interstratified serpentines [2], which makes their study complex. Moreover, the Ni-Mg distribution in octahedral site may be heterogeneous or form clusters at a nanometric scale [5]. The preliminary studies of Villanova-de-Benavent et al. [6] and Cathelineau et al. [7] showed a high sensitivity of the OH stretching and the low wavenumber region to the different mineral phases (talc, serpentine, kerolite). Raman spectroscopy seems thus to be a per-formant tool to easily determine the mineral phases in a garnierite sample.