Horomanite and samaniite are found in the interstices among grains of silicate minerals in lherzolite from the Horoman peridotite massif, Samani-cho, Hokkaido, Japan. The mean analytical data for the horomanite, as determined by electron-probe micro-analysis (EPMA), are Cu: 0.43, Fe: 41.82, Ni: 23.76, Co: 0.52 and S: 33.29 for a total of 99.82 wt%. The empirical formula is (Fe_5.77Ni_3.12Co_0.07Cu_0.05)_Σ9.01S_8.00. Crystallographic data for the horomanite acquired by X-ray single-crystal (precession) and powder (Gandolfi) diffraction methods. They revealed a tetragonal symmetry, space group P4/mmm, a = 8.707 Å, c = 10.439 Å, V = 791.4 ų, and Z = 4.
The mean chemical composition of samaniite obtained by EPMA is Cu: 16.90, Fe: 34.60, Ni: 15.48, Co: 0.16, and S: 32.87 for a total of 100.01 wt%. The empirical formula is Cu_2.08(Fe_4.84Ni_2.06Co_0.02)_Σ6.92S_8.00. The crystallographic data for samaniite, which were obtained by X-ray single-crystal and powder-diffraction methods, are tetragonal symmetry, space group P4₂/mnm, a = 10.089, c = 10.402Å, V = 1058.9Å3, and Z = 4.