<p>Mush processes are important in the formation of magmatic sulfide deposits, yet they remain poorly understood. The world-class Xiarihamu Ni-Cu deposit consists of two distinct lithological units: a Phase I olivine-free pyroxenitic unit and a Phase II olivine-enriched unit. Sector and normal zoning patterns of Cr in orthopyroxene from two phases indicate multiple-stage growth, involving rapid core crystallization during cumulus stages and overgrowth from interstitial melt during postcumulus stages. High-precision microprobe profile analyses reveal complex Mg-Ca-Al-Ni-Na zonings in orthopyroxene strongly coupled with Cr, exhibiting growth features with minimal diffusional overprint. In contrast, olivine exhibits Fo values (85–89&#xa0;mol%) and trace element concentrations (Ni, Mn, Zn, Co) that correlate with the abundance of cumulus phases, reflecting extensive postcumulus resetting via diffusive re-equilibration with interstitial melts. The contrasting response of olivine and orthopyroxene to mush processes is attributed to their contrasting element diffusivities, with lower diffusivities in pyroxene allowing it to retain primary magmatic features. The limited variation in Mg# across Cr–Al sector-zoned orthopyroxene suggests that Mg# is largely unaffected by intracrystalline partitioning and thus records magmatic differentiation. Distinct correlations between Mg# and Ni, Co, Zn, and LREEs in orthopyroxene reflect divergent evolutionary trends in the parent magmas of the two units. However, interstitial clinopyroxene from both units displays similar variations in major and trace elements, indicating interstitial melt chemical homogenization within mushes. The zoning and geochemical patterns in Xiarihamu minerals indicate the presence of a relatively thick mush zone during solidification, facilitating dynamic sulfide migration and accumulation during mush evolution.</p>