Among the fumarolic products of Etna volcano, cassiterite has been found for the first time. The rock, where the mineral occurs, is described. The Etna volcano cassiterite shows, from diffractometric data, the follolattice parameters: a₀ = 4,738 Å, c₀ = 3,188 Å. Rock fragments carrying the sublimates were analyzed spectrographically in order to ascertain the presence of tin. An hypotesis on the genesis of the Etna cassiterite is given on the basis of the established coexistence of HCl and HF with the mineral.