The processing of the data revealed that all the samples represent Fe-biotite crystallized directly from the magma and that they are not affected by the subsequent subsolidus processes.

The biotite from pegmatite crystallized from moderately oxidized magma at lower temperatures than biotites from granitoids. The geochemistry of biotites from granitoids indicates a low degree of magma oxidation and higher temperatures. The distribution of octahedral cations in the bivariate diagrams suggest the presence of two batches of melts that led to the formation of different textural types of granitoids, massive and gneissic, a hypothesis supported also by the values of Mg# and by Fe/Fe+Mg ratio.

In the gneissic granitoids, biotites are accompanied by muscovite, while in the massive varieties biotites are unaccompanied by other ferromagnesian or aluminous minerals.

The study of the abundance of trace elements in biotites and in their host rocks indicates that over 50% of the total quantity of Zn, Cs, Nb and Ta and a large quantity of Rb, Sc, V, Ga and U from Vința granitoids are concentrated by the dark mica.