Stable isotope systems of iron, copper, and zinc have emerged as powerful tracers in understanding metal sources, migration, and deposit formation processes. Accurate and precise determination of Fe, Cu, and Zn isotopic compositions in sulfide minerals, especially in simple-matrix minerals characterized by their relatively pure composition, with low content of impurity elements and few interfering components, requires matrix-matched reference materials to validate analytical methods, particularly for direct analysis protocols without column chromatography. This study introduces a suite of novel secondary reference materials (NWU-Fe, NWU-Cu, and NWU-Zn sulfide powders) developed to address the critical gap in calibration standards for direct isotopic analysis without column chemistry of simple-matrix minerals. These sulfide powders exhibit excellent homogeneity and stability, fulfilling the requirements for high-precision determination of Fe, Cu, and Zn isotope ratios using MC-ICP-MS without column chemistry. Reference values were derived from interlaboratory comparisons across three independent laboratories. The isotopic compositions (δ-values), reported in per mil notation relative to international standards (IRMM-014 for Fe, NIST SRM-976 for Cu, and JMC-Lyon for Zn), are as follows: δ56Fe = -0.38 ± 0.03‰ (2s), δ65Cu = 0.44 ± 0.04‰ (2s), δ66Zn = -0.04 ± 0.02‰ (2s). This study provides a robust calibration framework for Fe-Cu-Zn isotopic studies in geochemistry and environmental science.