1998 年 93 巻 10 号 p. 369-379
Ni-bearing minerals such as pentlandite, heazlewoodite, unknown sulfide minerals X, Y and Z are found in the Horoman peridotite, Hokkaido, Japan. Cu-rich mineral of talnakhite, bornite and native copper also occurs associating with Ni-bearing minerals. Pentlandite has the compositional range from 4.276 to 5.238 in atomic ratio of Fe (total atoms=17) changing coexisting minerals. Unknown sulfide mineral X has composition with Cu: 0.010∼0.144, Fe: 5.573∼6.044: Ni: 2.800∼3.392, Co: 0.047∼0.109, S: 7.884∼8.109 in atomic ratio (total atoms=17) and its ideal formula is (Fe, Cu)6Ni3S8. The compositional range of unknown sulfide mineral Y is Cu: 0.573∼1.003, Fe: 5.783∼6.154: Ni: 1.875∼2.392, Co: 0.012∼0.036, S: 7.953∼8.099 in atomic ratio (total atoms=17), and most copper rich end corresponds to CuFe6Ni2S8. Unknown sulfide mineral Z has ideal formula of Cu2Fe5Ni2S8. Pentlandite and unknown sulfide mineral X occur as primary minerals in the peridotite. Talnakhite and bornite are also found and has their ideal compositions.