Magnesium cluster beams have been obtained from supersonic nozzle expansions. The low boiling point of Mg (1363 K) allows conditions for clustering to be reached with and without argon as a carrier gas. This article reports on cluster size and intensity as a function of expansion conditions, and discusses the characteristics of magnesium films obtained by cluster-beam deposition. The source parameters were temperature T0 less-than-or-equal-to 1600 K, total pressure p0 less-than-or-equal-to 5000 hPa, magnesium partial pressure p(Mg) less-than-or-equal-to 2600 hPa, supersonic conical nozzle : diameter d = 0.25 mm, cone angle 2alpha = 10-degrees, and cone length l = 27 mm. For the Ar/Mg mixture the cluster-beam intensity corresponded to deposition rates of up to 83 nm/s at a 0.3 m distance from the nozzle. This exceeds the "ideal" intensity from a sonic nozzle operated with the same magnesium mass flow by about a factor of 3.5. For the neat Mg vapor the deposition rates extended up to 190 nm/s, but at a higher Mg mass flow compared to the Ar/Mg mixture. The cluster beams were deposited on room-temperature glass and Si(111) substrates. Films about 1000 nm thick were examined by x-ray diffraction. Compared to films produced by atomic beam deposition with a typical polycrystalline structure the cluster films are distinguished by a preferential orientation of (002) planes parallel to the substrate. This feature was observed for both types of cluster beams, with and without argon as a carrier gas, and for both glass. and Si substrates. The highly specular film surfaces turned usually into a golden-yellow color after, exposure to air, with the notable exception of the film formed with the highest intensity (510 nm/s). The surface structure studied with an atomic force microscope showed an increase in grain size with increasing deposition rate.