The Mössbauer effect in 119Sn and 57Fe was employed to study and characterize small clusters of FexSn y formed and stabilized in a solid argon matrix. Various low concentrations of Fe and Sn atoms with respect to Ar were used (0.1-0.5 at. %), resulting in formation of dimers and trimers. The constituencies and geometrical structures were confirmed by self-consistent assignment of the 57Fe isomer shift, quadrupole splitting, line width, and relative intensities of the 57Fe and 119Sn lines. Apart from the the monomers and dimers of Fe and Sn the following species were characterized, namely: FeSn, Fe2Sn, FeSn2, SnFeSn, and Fe3. Conclusions were derived regarding the reactivity of Fe and Sn atoms and dimers in the matrix preceding solidification of argon. The nature of Fe-Sn bond is discussed in terms of the 57Fe hyperfine constants.