Last years in isotope researches of mafic-ultramafic rocks it is actively applied U-Pb ratio in zircon and baddeleites. Authors had been investigated zircone and baddeleites in thinsections, and also zircon monofractions, selected from Golets paleovulcano sections (lava fraction) and Ruiga subvolcanic chamber, Vyzhiga intrusion, Avdeevo and Shala dykes, and also dykes from a rivers Vodla and Sukhaya Vodla valley, from volcanic rocks of B.Levgora's and Myandukha sites. Minerals were diagnosed by the microanalyzer «INCA Enerdgy 350» on the basis of a scanning electronic microscope «VEGA II LSH» at Institute of geology Karelian SC of the Russian Academy of Sciences. The sizes and the form of grains of baddeleite are different, depending on a magmatic body: they are pure and large (to 10 ìêm) in Ruiga; they always have a cover of zircon in Vyzhiga massif; allocated in dykes they can be devided into 2 generations -they have wrong form (less often) and the narrow well faceted needles. The structure of baddeleites is characterised by presence of impurity Hf, Au, Re.
The conclusion is drawn that the main minerals for isotope researches of these rocks are baddeleites as the most representative minerals of zirconium - derivatives the basic-ultrabasic magma. Their presence is established in intrusions, dykes, and is rare - in the basis of such large objects, as lava lakes. Baddeleites are rather characteristic for dykes the mafic composition. They are not met in spinifex zones of lava covers and streams.