Népouite is a rare nickel silicate mineral which has the apple green color typical of such compounds.

There is a similar mineral called lizardite (named after the Lizard Complex in Cornwall, England) in which all of the nickel is replaced by magnesium, formula Mg3(Si2O5)(OH)4.

[6] These two minerals form a series; intermediate compositions are possible, with varying proportions of nickel to magnesium.

Associated minerals include calcite, chlorite, goethite, halloysite, nontronite, pimelite, quartz, sepiolite, serpentine, talc and willemseite.

As well as the type locality in New Caledonia, it is present in Australia, Austria, the Czech Republic, the Democratic Republic of Congo, Germany, Greece, Italy, Japan, Morocco,[9] Poland, Russia, South Africa and the United States.