Extensive corundum-forming breakdown of kyanite in quartz veins emplaced during the retrograde evolution of eclogites, Căpățânii Mts., South Carpathians

Large platy symplectitic aggregates composed of corundum and albite appear in quartz veins crosscutting heavily retrogressed eclogites in the Căpățâna Mountains, South Carpathians. They were identified as pseudomorphs after kyanite initially formed in the veins. Protracted circulation of reactive fluids of alkaline composition along the veins produced corundum-forming breakdown of kyanite. Sluggish aluminium silicate – forming reaction between quartz and corundum enabled metastable coexistence of the two incompatible minerals, which were nevertheless found separated by a seam of biotite rather than in direct contact.