par Jedwab, Jacques 
Référence Mineralogy and petrology, 43, 2, page (137-146)
Publication Publié, 1990-11
Référence Mineralogy and petrology, 43, 2, page (137-146)
Publication Publié, 1990-11
Article révisé par les pairs
| Résumé : | Native Ru has been found in several samples of tantalum carbide collected in the Urals before 1914. Ru crystallized with a rectangular habit but now has hexagonal symmetry. The chemical composition is Ru-Ta alloy (Ta = 7.56 ± 0.7 wt%) and it is entirely devoid of other PGEs. This unusual composition, the fact that PGMs are not found intergrown with the Ru, and that magnetite and ilmenite, rather than chromite, are found among the associated placer minerals, indicates that the petrological affinity of the Ru is pyroxenitic, rather than dunitic or peridotitic. It is suggested that pure native Ru is more widespread than hitherto observed and that identification may be impeded by specific detection difficulties which were met with during this study (i.e., extremely small sizes, strong adhesive properties, unfavourable optical properties). © 1990 Springer-Verlag. |
