JAXA's Hayabusa2 sample return mission visited the volatile‐rich carbonaceous (C‐type) asteroid (162173) Ryugu with the aim of ground‐truthing remote observations, returning a pristine sample from a C‐type asteroid, and strengthening links between asteroids and the meteorite collection. Here, we have conducted a systematic study of coarse (>10 μm) sulfide grains in Ryugu particles C0025‐01 and C0103‐02, the CI chondrites Orgueil and Ivuna, and the CY chondrites Y‐86029 (Stage III, heated to 500–750°C) and Y‐86720 (Stage IV, >750°C), using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Sulfides are sensitive tracers of secondary alteration conditions, and we find that Ryugu and the CI chondrites share a distinct sulfide assemblage that includes the iron sulfides pyrrhotite and pentlandite, and the copper sulfide cubanite, that equilibrated during periods of low temperature (~25°C) aqueous alteration. Sulfides in the CY chondrites are compositionally distinct from Ryugu and the CI chondrites as a result of post‐hydration heating. However, the occurrence of Cu‐rich sulfides in Ryugu, the CIs, and the CYs suggests a genetic relationship between these samples
