line-height-rule: exactly" class=MsoNormal>Three types of dunite occur in the Luobusa ophiolite, a thick layer of transition zone dunite, thin envelopes of dunite around podiform chromitites and small bands and lenses of dunite in the harzburgites, respectively. The transition zone dunite in the Luobusa ophiolite is distinctly different from classic ultramafic cumulates, and most likely formed by reaction between tholeiitic basalt melt and mantle peridotite. Dunite lenses in the harzburgite may reflect either inhomogeneous partial melting of the host peridotites or in-situ melt-rock reaction. The dunite envelopes around the podiform chromitites are thought to have formed in the same way as the transition zone dunite, but the origin of the massive chromitites is not clear.