Why do parts of New Caledonia have distinctive red soils?

Parts of New Caledonia feature distinctive red soils, known locally as terre rouge, due to the weathering of ultrabasic serpentine rock formations.1

These rocks cover much of the southern third of the main island and parts of the west coast. As these formations weather, they produce the characteristic red color associated with the island's extensive deposits of nickel, chrome, and cobalt ore. Generally, the reddish hue in tropical soils is caused by the presence of iron oxides that form during the process of chemical weathering.12