A Ni-rich, planar serpentine where Ni is greater than 50% of the octahedral substitution (Brindley and Wan, 1975), typically Ni_xMg_3-xSi₂O₅(OH)₄. Nepouite forms a series with lizardite, the Mg (platy) end member. Stacking disorder dominates, but specimens may approach monoclinic and orthorhombic stacking sequences. Occurrences are complex, but generally involve weathered ultramafics that produce serpentinites followed by lateritic weathering, as is the case for the Ni deposits of New Caladonia.
Syn., nepouite.