Metallic microinclusions of the extremely rare ruthenium-osmium arsenide anduoite from the type locality in Anduo, Tibet, in a specimen that was analyzed. Evidence of the analysis is still present in the specimen since it is a polished section with a thin sheet of copper, usually used to make the sample conductive under the SEM/EDS machine. Associated mineral species are irarsite and rutheniridosmine, which match perfectly with the material from the type locality described in Mindat ("Best of"article"): "The mineral occurs as massive grains or granular aggregates (60 to 100 μ) in a chromium deposit related to augite, peridotite, and dunite…Anduoite and other arsenides and sulfarsenides, often distributed around the grains of rutheniridsosmine, are closely associated with irarsite and show replacement of irarsite". Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Anduoite
Anduoite is an IMA-recognized mineral species in the sulfide class, with the chemical formula RuAs₂.
It crystallizes in the orthorhombic crystal system (space group Pnnm).
Key properties: specific gravity 8.692; Grayish black streak; Dull metallic luster.
IMA symbol Adu, IMA status: approved, named in 1979.
Of magmatic origin, as very rare inclusions in chromian spinel in chromitite bodies enclosed variously by augite peridotite, serpentinized dunite, harzburgite, and pyroxenite.
It is found associated with Chromian spinel, pyrite, pyrrhotite, marcasite, magnetite, chalcopyrite, molybdenite, galena, millerite, violarite.
The name refers to the Chinese locality at Anduo.