We identified a ~4-micrometer-long, ~1 x 10^-10 g "nugget" of Ir metal in a melt rock sample from the Chicxulub impact basin. This particle, which consists of an aggregate of subhedral Ir metal grains surrounded by a thin coating of silicate, was isolated in the course of our efforts to better understand the partitioning of projectile material between crater deposits and ejecta in large meteorite impact events. In addition to confirming earlier reports of Ir in melt rock and melt breccia within the K-T boundary source crater, the results of our search for physically identifiable carriers of meteoritic components provide additional evidence for extreme fractionation of siderophile elements and their concentration in sparsely disseminated trace phases.