Trace amounts of sulfide, ranging from 0·06 to 0·26 volume per cent, are present in the garnet pyroxenite xenoliths in nepheline basalt at Salt Lake Crater, Oahu, Hawaii. Microscopic study revealed the existence of three chemically and physically distinct sulfide types, i.e. enclosed, interstitial, and vein sulfides. The enclosed sulfide forms spherical inclusions in primary pyroxene, garnet, ilmenite, and spinel. It has a bi-modal chemical character, which may be in part due to alteration of some of the enclosed sulfide grains by the nepheline basalt host magma, but more probably represent Cu-Ni-rich sulfide liquid coexisting with Cu-rich monosulfide solid solution. The interstitial sulfide is uni-modal and occurs in the interstices of the primary silicates. It has been subjected to intense chemical alteration by the nepheline basalt host magma. As a result the interstitial sulfide became Cu-poor with a varying Ni content, which indicates that complete chemical equilibrium with the basalt host magma has not been attained.