抄録
A new mineral ruthenium in a concentrate from the Horokanai platinum placer, Hokkaido, is described.
Electron-microprobe analysis of this mineral gave the following weight percentages: Ru 64.43, Ir 14.62, Pt 9.14, Rh 7.05, Os 5.29, Pd 0.49, Fe 0.21, Ni tr., Cu tr., total 101.23. The result corresponds to the composition Ru1.47Ir0.18Rh0.16Pt0.11Os0.06Pd0.01Fe0.01, and the proportions between three prin-cipal metals are Ru:Ir:Rh=81.5:9.7:8.8, which falls in the region of mineral ruthenium because Ru content is more than 80 atomic percent of the three elements. This mineral is, therefore, named ruthenium after its chemical composition.
Reflection colour is white with light creamy tint, and reflectivity is about 60 percent. It shows optically weak anisotropism. It occurs as a tabular crystal associated with rutheniridosmium in the peripheral area of a platinum grain. The size of the crystal is 35×7 microns in polished section.
The mineral ruthenium and the name have been approved by the Commission of New Minerals and Mineral Names, IMA.
