Quartz-microcline-albite pegmatites of the Otboynoe deposit contain diverse rare metal mineralization of Ta and Nb, as well as Li, Zr, Rb. Two representative ore technological samples have been studied by microprobe, optic microscopy, X-ray powder diffraction, chemical methods. The derived results showed: 1) rubidium is concentrated mainly in microcline and much lesser in muscovite and especially in albite; 2) Rb2O content in microcline range from 0.00 to 3.04 wt. %, average is 1.66% (by 34 analyses). ). Obtained from pegmatites K-feldspar concentrate containing 0,91 wt. % Rb2O allows to consider Rb-bearing microcline as potential source of this passing useful component.